PocketBook Demag ENG

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No other publication enjoys such a long tradition as a key

source of information as the "Injection Moulding Pocketbook".

We realise from the many requests we have for copies of the

booklet from right across the injection moulding industry that a

new edition is now needed. This latest publication represents

the completion of our reference work on the subject of injection

moulding.

Technological developments are not so much the focal point

here. It is the complete optimisation of the injection mouldingmachine, which includes the evaluation and selection of pro-cess parameters and the elimination of surface defects, that iscentral to this handbook.

We should like to thank Martin Bichler, Gunter Seibold,

Ansgar Jaeger, Fritz RoBner and Dr. Sabine Pahlke for their

active support.

Injection Moulding Pocketbook

Special publication fromMannesmann Demag Kunststofftechnik

1st edition 10/97, circulation 20.000Copyright6 1997 by Mannesmann Demag Kunststofftechnik

Id. no.: 183 790 65

1 Procesul de injectie....................... 4

Principii 5

2 Prima reglare a unei masini de injectie

2.1 Pregatiri....... 6

2.2 Pregatirea masinii....... 8

2.2.1 Reglarea unitatilor de inchidere cu articulatie 8

2.2.2 Reglarea unitatilor de inchidere hidraulice 10

2.3 Reglarea unitatii de injectie 11

2.4 Inceperea productiei 12

3 Desfasurarea ciclului de injectie la o masina ERGOtech

3.1 Inchiderea unitatii de inchidere 14

3.2 Faza de injectie si cea de presiune ulterioara 16

3.3 Dozare, snec si retragerea unitatii de injectie 18

3.4 Deschiderea unitatii de inchidere 20

4 Mic indrumar despre materiale

4.1 Indicatii la prelucrarea celor mai importanti polimeri 22

4.2 Caracteristici de recunoastere a maselor plastice 74

4.3 Temperaturi de prelucrare si pre-uscarea 78

5 Optimizarea procesului la masina de injectie

5.1 Caracteristici de calitate si parametrii de proces 81

5.2 Calcularea timpului de racire 91

6 Evaluarea corecta si alegerea parametrilor importanti

din punct de vedere al calitatii pentru asigurarea calitatii

pieselor injectate 97

7 Identificarea si eliminarea defectelor de suprafata

la piesele injectate 119

8 Exemplu de calcul al fortei de inchidere 125

9 Instructiuni de operare cu sistemul de control

ERGOtech NC4 137



Procesul de injectie matritata

In ultimele decenii procesul de injectie matritata si tot ceea ce este

in legatura cu acesta, s-a dezvoltat mai puternic decat aproape

toate celelalte procese de fabricatie cuprinzand o varietate din ce

in ce mai larga de produse. Avantajele sunt clare:

• material convenabil

• consum redus de energie la matritare datorat temperaturilor

scazute de procesare

• cale directa de la materia prima la produsul finit (operatiune

intr-un singur pas, fara finisari ulterioare)

Exista o multitudine de factori de influenta care se pot combina pentru

a obtine eficienta si inalta calitate si, daca sunt corect selctionati si

folositi, conduc la obtinerea, prin injectare matritata, a unor produse

de prima clasa.

Factorii de influenta in productia prin injectie sunt clasificati dupa

cum urmeaza:

1. Om

Motivare, calificare, flexibilitate, experienta ...

2. Masina pentru injectat

Ergonomicitate, eficienta, acuratete, fiabilitate, proiectare corecta,

optiuni de monitorizare ...

3. Matrita

Componenta orientata catre material si exact proiectata,proiectare termica, rigiditate, intretinere ...

4. Materia prima

Corect aleasa, curata, pre-uscata,

5. Periferice

Unitati control temperatura, control canale calde ...

6. Mediul ambiant

Siguranta, influentele mediului ...

Omul este unicul factor de influenta ce are abilitatea de a invata si de a

reactiona. Acest fapt il pune intr-o pozitie delicata si odata cu cresterea in

complexitate a procesului de injectie el are nevoie din ce in ce mai mult

de un suport pe masura.

Obiectivul acestei Carti de Buzunar este de a oferi ceva din acest suport.

Princii

Acuratetea si ordinea sunt strict necesare pentru aplicarea unei

metode sistematice de lucru. Aceasta poate incepe cu repunerea

capacului pe palnia de alimentare sau resigilarea sacilor deschisi

de materia si incheiat cu intocmirea documentatiei informative

folositoare pentru fiecare pas din optimizarea procesului.

Este deasemenea important sa acordati atentie influentelor

constante ale mediului si a se evita lasarea usilor deschise, ventila-

toare sau unitati de incalzire pornite in vecinatatea masinii.

Intr egul echipament din sectia de productie trebuie intretinut cu

regularitate. Inclusiv masina, matrita si toate unitatile periferice

Din motive de siguranta urmatoarele lucruri trebuie supravegheate

pe parcursul productiei:

• Sa se lucreze la matrita deschisa numai atunci cand pompa

este oprita.

• Sa se utilizeze manusi si incaltaminte de protectie si sa sefoloseasca o tija de cupru cand se lucreaza la canalele calde.

• Toate mecanismele de siguranta ale masinilor se verifica la

intervale regulate.

Avand toate aceste indatoriri, atunci cand se face reglarea masinii,

reglorul trebuie sa fie capabil sa acorde toata atentia masinii si proce-

sului. Similar, operatiunea de reglare nu trebuie sa fie doar o

operatie de citire a unor tabele si formule, ci fiecare valoare se

considera in mod logic si se analizeaza. Observand aceste reguli

de baza si urmatoarele indrumari in procesare si punandu-le in practica

ve-ti dispune de toate cele necesare procesului de prelucrare prin

injectie a maselor plastice.

Speram ca ve-ti parcurge cu placere acest indrumar si va uram

succes in reglarea masinii dumneavoastra de injectie.

4 5



Reglarea primara a unei

imasini de injectie mase plastice

2.1 Preliminar - lista de verificare

Articol injectat

Am mai produs acest reper in trecut ?

Pe ce tip de masina?

Datele de reglaj sunt deja disponibile pe un hard disk, floppy disk etc.?

Cate repere sunt necesare?

Pana cand?Este necesar echipament special pentru masurare?

Materialul, dimensiunile si greutatea reperului?

Matrita

Unde este matrita depozitata?

Aceasta matrita necesita reparatii sau reparatiile au fost deja facute?

Cum poate fi transportata si ridicata pe masina?

Ce dispozitiv de prindere este necesar pentru fixarea matritei pe

masina?

Parametrii urmatori au fost urmariti pentru a verifica compatibilitatea

matritei cu masina folosita?

• dimensiunile de fixare a matritei

• cercul de centrare

• capacitatea de injectie

• tija aruncatorului si cuplajul masinii (dimensiuni pentru conectare)

• nozzle radius and bore and corresponding sprue bush size

it additional equipment (core pullers etc.)

Are peripheral units required such as temperature control units,cooling units, hot runner controllers, conveyor belt?

Are the fittings on the cooling water connections on the

machine and the mould compatible?

Has the mould been leak-tested in the cooling water region?

Machine

Is the proposed machine available for the productiontarget date?

Is the maximum clamping force sufficient?

Has the necessary maintenance work been carried out?

Has the machine been running problem-free lately?

Is the appropriate screw cylinder available

(cylinder head volume, injection pressure)?

Material

Is there sufficient material for the job?

Where is the material stored?

Does the material need to be pre-dried?

Is there a supply of masterbatch, if required?



2.2 Preparing the machine

2.2.1 Setting up the clamping unit for

ERGOtech toggle machines 125 to 1300

Attention!

All mould adjustments to be made in set-up mode only

(For pressure and speeds see screen page 10 on NC4 IBED)

1. Extend the toggle. The ACTUAL value for*mould stroke

must be "0".

2. Using the "Mould height" function keys,'set platen distance

slightly greater than the mould height.

3. Move the moving platen to maximum opening distance.

4. Attach the mould securely to the lifting gear.The mould must hang straight. Make sure that the mould

halves cannot slide apart.

5. Protect the machine tie bars from damage during mould

installation.

6. Position the mould on the fixed platen, centre and attach.

If the mould is to be fixed using clamping shoes ensure a

proper fit.

7. Extend the toggle. Mould stroke on the IBED must indicate"0". Take care that the ejector rod moves into the ejectorcoupling without being forced. Now by using mould heightadjustment move the moving mould half until platen contactis made. Clamping force is now "0" kN.

8. Tighten the mould half on the moving platen. Remove

safety strap from mould, if used. Connect the ejector rodwith the ejector coupling using the slide mechanism.

9. Open the mould far enough to allow the moulding to fallout safely in due course. An accurate setting of the openingstroke can be made later when optimising the injectionmoulding process.

10. Enter clamping force. When the Start key is pressed theclamp unit moves automatically to approx. 75% of the setvalue of the clamp force. In automatic mode, when clampforce control is fitted, clamp force is regulated in stages to100% of the pre-selected value. If necessary, clamp forcecan be increased or decreased using the "Mould height"function key.

11. Now move the clamp unit in set-up mode until platencontact is made and read off the ACTUAL value for mould

stroke.

The stroke point for "Mould protection end" must be setapprox. 0.5 mm higher than the ACTUAL value displayed,in order to be able to lock the mould.

12. The speeds and change-over points for the mould andthe ejector must be compatible with the specification ofthe mould (see comments in chapter on Cycle Sequence).

13. When clamp force is set, tighten the clamps up on the

mould. If necessary, heat the mould beforehand.



2.2.2 Setting up fully hydraulic machines

ERGOtech 25 to 110

Attention!

All mould adjustments to be made in set-up mode only

1. Move clamp unit to maximum opening distance.

2. Attach the mould securely to the lifting gear. The mouldmust hang straight. Make sure that the mould halves cannot

slide apart. ''3. Protect the machine tie bars from damage during mould

installation.

4. Position the mould on the fixed platen, centre and attach.If the mould is to be fixed using clamping shoes, ensure aproper fit.

5. Move the clamp unit until platen contact is made, takingcare that the ejector rod moves into the ejector couplingwithout being forced.

6. Set mould height using the program switch. ACTUAL mouldstroke is indicated as 2 mm.

7. Tighten the mould half on the moving platen. Removesafety strap from mould, if used. Connect the ejector rodwith the ejector coupling using the slide mechanism.

8. Enter required clamp force.

On Compact machines the required hydraulic pressure mustalso be set using a manually operated valve to correspondwith the value displayed under "Clamp force".

9. To achieve clamping pressure, stroke point"Mould protection end" must be approx. 0.5 mm higherthan the set mould height.

10. The speeds and change-over points for the mould and theejector must be compatible with the specification of themould (see comments in chapter on Cycle Sequence).

11. When clamp force is set, tighten the clamps up on the

mould. If necessary, heat the mould beforehand.

10

2.3 Setting the injection unit

Follow instructions in the operating manual to change thescrew cylinder.

1. Enter the material-related temperatures required for thecylinder heating zones and for flange temperature control.

2. Turn on water supply to the machine.

3. Switch on cylinder heating.

4. Set reference point for injection unit.All heating zones must be up to SET temperature and the

mould must be locked.

5. In set-up mode, move the nozzle to contact with the mould.Then set to zero using program switch "Reference point IU".

6. Check nozzle radius centring and dipping depth.

7. Enter nozzle contact pressure, strokes and speeds for the

injection unit.

8. Enter metering stroke according to the necessary shot

weight. Calculate, if need be, taking into account the neces-sary melt cushion.

9. Enter injection pressure, injection speed, follow-up pressure,follow-up pressure time, cooling time, back pressure andscrew speed. See Chapter 4.1 "Processing Guidelines".

10. Switch on program switch "Change over to follow-up pres-

sure dependent on volume" (pN volume).

11. Enter stroke point for "Follow-up pressure start". Follow-uppressure start should occur at around 80 to 90 % of the

shot volume. As a rule, we recommend that a mould fillingstudy be made on new moulds to determine the exactchange-over point. In this case, follow-up pressure shouldbe set to "0".

12. If necessary, set decompression to release pressure of melt

in the cylinder if an open nozzle is used.

11



2.4 Starting the injection process

When all settings have been checked the machine can beswitched to the "semi-automatic" program. To enable themachine cycle to commence once the Start key has beenpressed, the following start conditions must be fulfilled:

• Mould open stop reached

• Ejector back

• Dosing Stop reached (dose manually beforehand and, if

necessary, depending on the type of material, purge the

material a few times). If one or several of the start conditions

is not met, alarms will be raised on theiBED.

As a rule, no monitoring functions or tolerances should be setduring the start-up phase.

The machine can be switched to "fully automatic" after a fewcycles, once the mouldings are being ejected and falling clear.At this point process optimisation can begin (more detailedinformation can be found in Chapter 5 "Process Optimisation

on the injection moulding machine"). The following sequenceis recommended:

• optimise dosing

• optimise injection speed

• determine follow-up pressure and follow-up pressure time

• limit injection pressure

• determine cooling time

• ensure smooth operation of clamping unit

• optimise clamping force

• carry out checks on mouldings

When the mouldings have reached the required quality standard

and the cycle time is satisfactory, the important parameters can

be monitored by setting tolerance limits using process control.

Safeguard the set machine data by storing the programme on

floppy disk. Also produce a hard copy.

12 13



The cycle sequence on

an ERGOtech machine

3.1 Closing the clamping unit

Fig. 1

Start conditions:

• Mould open stopif Hydraulic ejector back stop

• Guard door closed

• Cylinder up to temperature

• Start key depressed

14

Operating sequence

Assuming that the machine is an ERGOtech compact or system

model to standard design, the cycle will proceed as follows:

(see Fig. 1)

• All Start conditions must be met to enable the clamp unit to

be started (in semi- or fully automatic operation). (See Fig. 1)

• The clamp unit moves from Pos. [1] - "Mould open Stop" to

Pos. [2] on high pressure and at speed "Mould close V1".

if At Pos. [2] "Mould close" there is a change of speed to"Mould close V2".

• At Pos. [3] "Mould close" there is a change of speed to

"Mould close V3".

• Pos. [3] should be set so that speed V3 comes into effect at

the very latest by the start of reduced mould clamping pres-

sure at Pos. [4],

i If Pos. [3] is set after Pos. [4] there will be an automatic

change over to V3 at Pos. [4],

• Pos. [4] - "Mould protection start" - reduced mould clamp-ing pressure begins. This switch over point should occur30-60 mm before platen contact or, in the case of a slidingsplits mould, before the angled dowel moves into the splits.

it Reduced mould clamping pressure should be set just high

enough for the mould to close.

is On platen contact - Pos. [5] - the high pressure must beswitched on again at the control panel at "Mould protectionend" to achieve the set clamping force.

• At the same time as the mould closing movement "Mould

protection time" (determined empirically") starts at Pos. [4]and should not have finished by Pos, [5]. Otherwise, thecycle would be interrupted. (Exception: activation of "Mouldprotection repeat" program).

= = s . = ii i SB is!

15

Presiune

Viteza

Pozitie



3.2 Injection and follow-up pressure phase

Fig. 2

Injection stages - max. 10

Follow-up pressure stages - max. 10

Start conditions:

a Clamp force reached

• Guard door closed

• Injection unit guard door closed

• Cylinder up to temperature

• Dosing Stop and "Screw back" reached

Operating sequence

• When start conditions have been met (see Fig. 2) the injec-tion unit moves forward to Pos. [8] on speed "IU forward V".

• At Pos. [8] there is a change over to speed "IU forward V2".

The injection unit now moves forward on speed V2 until the

cylinder nozzle makes contact with the sprue bush on the

mould Pos. [9],

• Nozzle contact pressure now starts to build. When the given

nozzle contact pressure is reached, this initiates the com-mand for injection.

• The set values for "Injection pressure" and "Injection speed"

are also required.

• "Follow-up pressure start" at Pos. [10] initiates stroke

dependent change-over from injection pressure to follow-up

pressure. Alternatively, the change-over to follow-up pressure

can occur depending on time or pressure.

• If it is necessary to inject at varying speeds, the process can

operate on up to 10 different speeds. The speeds andstroke-dependent change-over points required can be set

on the "Injection profile" page.

• The follow-up pressure phase is operative from Pos. [10]

to Pos. [11]. If follow-up pressure needs to be stepped, this

can be set on the "Follow-up pressure profile" page.

in A reading for the actual melt cushion can be taken from the

Process Optimisation page.

• The actual value for the melt cushion should not be much

above or below the tolerance limits. The tolerances are set

on the "Process control" page.



3.3 Dosing, screw and injection unit back after dosing

Fig. 3

Dosing - max. 6 stages

Back pressure - max. 6 stages

Start conditions:

All activated follow-up pressure times have elapsed

Delayed feed has finished

"Screw back before dosing" has been completed, if sef

"IU back after dosing" program

19

Opera t i ng sequence

When the "Follow-up pressure times" have finished, "Cooling

time" begins. Dosing (melt processing) begins at Pos. [12]

when "Delayed feed" (Time) is over. Fig. 3.

Dosing begins at "Screw speed" Stage 1 and "Back

pressure" Stage 1 and ends at "Dosing Stop" Pos. [13].

It is possible, however, to operate on up to 6 different screw

speeds and 6 different screw back pressures per cycle. The

relevant change-over points can be set on the "Dosing pro-files" page,

Next, if set, comes screw decompression with "Screw back

after dosing" up to Pos. [14].

If the program "III back after dosing" is switched on, the

injection unit can be moved back on 2 speeds.

When time "IU back delayed" has elapsed, the injection unit

moves back on speed "IU back V1". At Pos. [15] there is a

change over to the second speed "IU back V2". The injection

unit now moves back on speed V2 as far as Pos. [16]

IU back stop".



3.4 Opening the clamping unit

Fig. 4

Operating sequence

• When start conditions have been met (Fig. 4) the clampingunit opens from Pos. [17] to Pos. [18] on speed "MouldopenVI".

• The slow speed facilitates the gentle demoulding of partsfrom the fixed mould half.

a With a sliding splits mould the change-over point"Mould open V1-V2" up to Pos. [18] is only activated after

the angled dowel is clear of the splits.• The clamping unit then moves to Pos. [19] on speed

"Mould open V2".

$ At Pos. [19] there is another change-over from speed

"Mould open V2" to "Mould open V3" to ensure smooth

running of the machine.

• The machine runs on this speed to Pos. [20]"Mould open stop".

• The entire opening stroke occurs at high pressure.

• The speeds for mould opening and mould closing and their

dedicated start points are shown on the "Speed profiles"

page.

Start conditions:

a Dosing stop

a "Screw back after dosing" is completed

• Injection unit back stop

a Cooling time is finished

20 21



Small material science

4.1 Processing guidelines for the most important plastics

This chapter sets out basic, relevant data for the treatment and

processing of the most important plastics.

Material Page

PP .' 23

PE : 26

PS 29

ABS 32

SAN 35

PA 38

POM 42

PC 46

PMMA 49

PPO 52

ABS/PC 55

PBTP 58

PETP 61

CA 64

PVC-U 67

PVC-P 70

22

Polypropylene, PP

Structure:

Partially crystalline

Density:

0.91-0.93 g/cm3

Thermal, optical, mechanical properties:Material is harder and more heat resistant than PE, but is less

resistant to low temperature (special low-temperature resistant

grade available). Particularly suitable for hinges. Hard, non-fragile,

excellent dielectric properties, non-toxic, not odour-proof.

Chemical properties:

resistant to

acids, alkaline solutions, salt solutions, alcohol, petrol,

fruit juices, oil, milk

not resistant to

chlorinated hydrocarbons, avoid contact with copper,

slight tendency towards stress cracking

Material identification:

PP is highly flammable, drips and continues to burn; burns brightly

with blue core, strong smell of paraffin (tar-like).

Cylinder temperature:

Flange 30- 50 °C / *50 °C

MH 1 160-250 °C/*200°C

MH 2 200-300 °C / *220 °C

MH 3 220-300 °C / *240 °C

MH 4 220-300 °C / *240 °C

DH 220-300 °C / *240 °C

* These temperature profiles are valid for stroke utilisation of between 35 and 65 % and

for parts with a flow length/wall thickness ratio of between 50:1 and 100 :1.

Si ~ S B IB

23



Melt temperature:

220-280 °C

Reduced cylinder temperature:

220 °C

Injection pressure:

There is no build up of very high injection pressure

(800-1400 bar), since flow characteristics are generally good.Exceptions are thin-walled packaging parts. An injection pres-sure of up to 1800 bar can result on these parts.

Follow-up pressure and follow-up pressure time:

Very long follow-up pressure times are necessary to avoid sinkmarks (approx. 30 % of the cycle time).

Follow-up pressure approx. 30-60 % of the required injectionpressure.

Back pressure:

50-200 bar

Injection speed:

Fast injection speeds are needed (accumulator) for thin-walledpackaging parts. Under other circumstances average injectionspeeds suffice.

Screw speed:

Peripheral velocity of 1.3 m/sec is the maximum screw speedon the machine. However, this should only be set as fast as isnecessary for the plasticising process to finish before coolingtime expires.

Recommended min. and max. dosing stroke:

0.5-4.0 D dosing stroke can be utilised.

Residual melt cushion:

2-6 mm, depending on dosing stroke and screw diameter.

24

Pre-drying:

Not necessary; under poor storage conditions perhaps 1 hour

at80°C.

Re-processing:

Up to 100 % regrind can be processed.

Shrinkage:

1.2-2.5 %. Final shrinkage can only be assessed after

24 hours.

Gating:

Pin gate or multi-point pin gate, hot runner, insulated runner,ante-chamber; gate at the strongest point of the moulding.

Machine shut-down:

No other material is required to follow up. PP is very resistant to

high temperatures.

Cylinder equipment:

Standard screw; for packaging parts special geometry L:D 25:1

with shear and mixing section. Open nozzle, non-return valve.

25



Polyethylene, PE (HDPE)

Structure:


Density:

0.92-0.96 g/cm3

Thermal, optical, mechanical properties;

Material is flexible to soft, resistant to terjiperatures up to-40 °C depending on density, impact resistant, indestructible.

Good dielectric properties, low water absorption, non-toxic,not odour-proof.


resistant to

acids, alkaline solutions, solvents, alcohol, petrol, fruit juices,

oil, milk

not resistant to

aromatic solvents, chlorinated hydrocarbons, risk of stresscracking


PE is highly flammable, continues to burn when removed from

source of heat, drips. Luminous flame with blue core, smells like

paraffin (snuffed candles).


Flange 30- 50 °C / *50 °C

MH1 160-250 °C/ *2 00 °C

MH 2 200-300 °C/ *210 °C

MH 3 220-300 °C/ *230 °C

MH4 220-300 °C/* 240 °C

DH 220-300 °C /*240 °C

* These temperature profiles are valid for stroke utilisation of between 35 and 65 %

and for parts with a flow length/wall thickness ratio of between 50:1 and 100:1.

2i iji.

26

Melt temperature:

220-280 °C


220 °C

Injection pressure:

There is no build-up of very high injection pressure

(800-1400 bar), since flowability is good. Exceptions arethin-walled packaging parts. An injection pressure of up to

1800 bar can result on these parts.


Long follow-up pressure times on dimensionaiiy accurate parts

due to relatively extensive shrinkage. Pressure approx. 30-60 %

of injection pressure.

Back pressure:

50-200 bar. Too little back pressure results in uneven mouldingweight or poor pigment dispersion during colouring.

Injection speed:

Fast injection speed (accumulator) required for thin-walled

packaging parts. Otherwise, average injection speed better.

Screw speed:

Peripheral velocity of 1.3 m/sec is max. setting for screw speed

on the machine. However, this should only be set as fast as is

necessary for the piasticising process to finish before cooling

time expires. Required screw torque is low.




2-8 mm depending on dosing stroke and screw diameter.

27



Pre-drying:

Not necessary. Under poor storage conditions, perhaps 1 hour

at 80 °C.

Re-processing:


Shrinkage:

1.5-2.5 %, substantial shrinkage, substantial warpage. Finalshrinkage can only be assessed after 24 hours. (After-shrink-

Gating:

Pin gate, hot runner, insulated runner, ante-chamber pin gate.

Relatively small cross sections suffice.

Machine shut-down:

No other material is required to follow up. PE is very resistant to

high temperatures.

Cylinder equipment:

Standard geometry for packaging parts; special geometry L:D

25:1 with shear and mixing section; open nozzle, non-return

valve.

Polystyrene, PS

Structure:

Amorphous

Density:

1.05 g/cm3

Thermal, optical, mechanical properties:

Hard, stiff, fragile, very good dielectric properties, low water

absorption, good dimensional stability, crystal clear, brilliant,

good pigmentability, no smell or taste.


resistant to

acids, alkaline solutions, alcohol, grease, oil, salt solutions

not resistant to

petrol, benzene, large number of solvents, risk of stress

cracking


PS is highly flammable, burns bright yellow, produces a lot of

black smoke, and typically smells slightly sweet (styrene).


Flange 30 - 50 °C / *50 °C

MH 1 160-220 °C/ *2 00 °C

MH 2 180-240 °C/ *2 10 °C

MH 3 210-280 °C/ *2 30 °C

MH 4 220-280 °C/ *230 °C

DH 220 -280 °C /*230 °C


and for parts with a flow length/wall thickness ratio of between 50:1 and 1 00:1.

28 29



Melt temperature:

220-280 °C


220 °C

Injection pressure:

There is no build-up of very high injection pressure

(800-1400 bar), because flowability is good.


Relatively short follow-up pressure time. Pressure level30-60 % of injection pressure.

Back pressure:

50-100 bar. If back pressure is set too low, this can result inair burns in the melt (displayed as grey or black streaks in themoulding).

Injection speed:

Generally fast. Stepped depending on shape of moulding.For thin-walled packaging parts, as fast as possible; partly with

accumulator.

Screw speed:

Fast screw speeds can be set up to a max. 1.3 m/sec peri-pheral velocity. However, plasticising is best carried out slowly

to suit cooling time.





Pre-drying:

1 hour at 80 °C if material has not been properly stored.

30

Re-processing:


Shrinkage:

0.3-0.6 %

Gating:

Pin gate, hot runner, insulated runner, ante-chamber. Relatively

small cross sections suffice.

Machine shut-down:

No other material is required to follow up. PS is resistant to high

temperatures.

Cylinder equipment:

• Standard screw

• Open nozzle

• Non-return valve

31



Acrylonitrile-butadiene-styrene, ABS

Structure:

Amorphous

Density:

1.06-1.19 g/cm3


Hard, tough even at -40 °C, good resistance to changes intemperature, resistance to low temperatures or heat (+100 °C)

depending on type, limited weather resistance, low water

absorption, non-toxic, electroplatable. Special purpose materialalso crystal clear.


resistant to

acids, alkaline solutions, hydrocarbons, oils, fats, petrol

not resistant to

acetone, ether, ethyl benzene, ethyl chloride, ethylene chloride,aniline, aniseed oil, benzene


ABS is highly flammable, burns bright yellow, produces black

smoke and typically smells slightly sweet (styrene).


Flange 40- 60 °C / *50 °C

MH 1 160-180 °C/*180 °C

MH2 180-230 °C/ *210°C

MH 3 210-260 °C/*24 0 °C

MH 4 210-260 °C/ *240 °C

DH 210-260 °C/ *240°C



Melt temperature:

220-250 °C


200 °C

Injection pressure:

1000-1500 bar


Relatively short follow-up pressure time. Pressure level

30-60 % of injection pressure.

Back pressure:

50-150 bar. If back pressure is set too low, this can result in

air burns in the melt (displayed as grey or black streaks in themoulding).

Injection speed:

Best stepped, slow injection to begin with, then fast (frontal

flow). Fast injection speed is good for achieving glossy, spar-kling surfaces, a good, strong weld line and only a slight weld

line mark. Venting channels are required on the weld line.

Screw speed:

Peripheral velocity of 0.6 m/sec is max. setting for screw speed.

However, it is better to set screw speed sufficiently slow so that

piasticising finishes shortly before cooling time expires.





a ii! ill 11! 11! il l -Si IS i ll !!! s z, 81 Si s m i!r 18 = = a = = m s

32 33



Machine shut-down:

No more material is required to follow up.

Pre-drying:

To some extent ABS can be processed direct from the original

bags without pre-drying. Otherwise, pre-dry for 3 hours at

80 °C. Damp material causes stripes, streaks or blisters on the

moulding.

Re-processing:

Providing the material has not already been charred, up to 30 %

regrind can be added to virgin material.

Shrinkage:

0.4-0.7 %

Gating:

Pin gate possible, likewise hot runner. Wall thickness should not

be less than 0.7 mm.

Machine shut-down:

No more material is required to follow up.

Cylinder equipment:

• Standard screw

iii Non-return valve

• Open nozzle

34

Styrene-acrylonitrile copolymer, SAN

Structure:

Amorphous

Density:

1.08 g/cm3


Excellent transparency and high gloss, good stiffness and

hardness. Good resistance to changes in temperature, good

chemical resistance, good heat resistance.


resistant to

acids, alkaline solutions, saturated hydrocarbons, mineral oils,

vegetable and animal fats

not resistant toconcentrated mineral acids, aromatic hydrocarbons and chlori-

nated hydrocarbons, ester, ether and ketone


SAN is highly flammable, burns bright yellow, is very smoky and

smells typically of styrene.


Flange 30- 50 °C / *50 °CMH 1 160-180 °C/*180°C

MH2 180-230 °C/ *2 10 °C

MH3 210-260 °C/ *2 40 °C

MH 4 220-260 °C /*240 °C

DH 220-260 °C /*240 °C



35



Melt temperature:

220-250 °C


200 °C

Injection pressure:

1000-1500 bar


Relatively short follow-up pressure time. Pressure 30-60 % ofinjection pressure.

Back pressure:

50-100 bar. If back pressure is set too low, this can result inair burns in the melt (displayed as grey or black streaks in themoulding).

Injection speed:

Fast injection speed is good for achieving glossy, sparklingsurfaces, a good, strong weld line and only a slight weld linemark.

Screw speed:

Max. screw speed equivalent to 0.6 m/sec peripheral velocity.Screw speed should always be set, however, so that plasticisingfinishes just before cooling time expires. Average screw torque

required.





36

Pre-drying:

If SAN is not stored or transported under the right conditions,it will absorb moisture. This can cause streaks, stripes or smallblisters to appear on the surface of the moulding duringprocessing.

Re-processing:

Providing no charring has occurred during initial processing,

up to 30 % regrind can be added to the virgin material. For highquality parts, however, virgin material should always be used.

Shrinkage:

0.4-0.7 %

Gating:

In principle, all types of gating systems can be used, and

likewise for hot runners.

Machine shut-down:

No other material is required to follow up.

Cylinder equipment:

• Standard screw


• Open nozzle

w

37



Polyamide, PA

Structure:


Density:

1.14 g/cm3


In balanced humidity (2-3 %), very tough. In dry conditions,

brittle. Hard, stiff, abrasion resistant, good frictional characteris-

tics. Good pigmentability, non-toxic, adhesive properties.


resistant to

oils, petrol, benzene, alkaline solutions, solvents, chlorinated

hydrocarbons, esters, ketone

not resistant to

ozone, hydrochloric acid, sulphuric acid, hydrogen peroxide


PA is flammable. It continues to burn when removed from

source of heat, drips and blisters, becomes stringy. Blue flame

with yellow rim. Smells like burnt bone.


PA 6

Flange 60- 90 °C / *70 °C

MH 1 230-240 °C/*240°C

MH 2 230-240 °C/ *2 40°C

MH3 240-250 °C/* 250 °C

MH 4 240-250 °C/*250 °C

DH 230-240 °C/* 250 °C

38

PA 6.6

Flange 60- 90 °C / *80 °C

MH 1 260-290 °C/*280 °C

MH2 260-290 °C/ *2 80°C

MH 3 280-290 °C/ *2 90°C

MH4 280-290 °C/ *2 90°C

DH 280-290 °C /*290 °C

1 Feed performance is most strongly affected by the flange temperatures and

the temperatures in zone MH 1. By raising these temperatures, feed performance

becomes more uniform.

Melt temperature:

PA 6 240-250 °C

PA 6.6 270-290 °C


PA 6 220 °CPA 6.6 250 °C

Injection pressure:

1000-1600 bar; on thin-walled articles with long flow paths

(cable clip) up to 1800 bar.


Normally, approx. 50 % of the resulting injection pressure. Short

follow-up pressure times are sufficient, as the material solidifiesrelatively quickly. As follow-up pressure decays, so the stress in

the moulding reduces.

Back pressure:

Set very accurately. 20-80 bar, as excessive back pressure

leads to uneven plasticising.

Injection speed:

Inject relatively quickly. Ensure that the mould is properly

vented, otherwise charring occurs on the moulding.

39



Screw speed:

Fast screw speed possible up to 1 m/sec peripheral velocity.However, it is better to set the screw speed slow enough, sothat plasticising finishes shortly before cooling time expires.Low screw torque required.


0.5-3.5 D dosing stroke.


Small melt cushion (2-6 mm), depending on dosing stroke and

screw diameter.

Pre-drying:

Polyamides are hygroscopic, so store in moisture-proof

containers. Close feed hopper!

A moisture content of more than 0.25 % creates processingdifficulties. Process directly from canister, otherwise pre-dry for

4 hours at 80 °C.

Re-processing:

10 % regrind can be added to virgin material.

Shrinkage:

PA 6

0.7-2.0%

PA 6.6

0.3-0.8%

PA 6-GF30

0.7-2.0%

PA 6.6-GF300.4-0.7%

Parts with operating temperatures above 60 °C must be an-

nealed. Annealing cuts down after-shrinkage i.e. the parts aredimensionaily more stable and have lower stress. Steam treat-ment works best. Polyamide mouldings can be checked forstress using soldering fluid.

Gating:

Possible gating systems include pin gate, tunnel gate, film gate,sprue gate. Blind holes are recommended for cold siugs.PA can also be processed using a hot runner. The temperaturein the hot runner must be accurately controlled, as the meltsolidifies within a limited temperature range.

Machine shut-down:

No other material is required to follow up. Melt dwell time in thecylinder is possible up to 20 mins, thereafter thermal degrada-tion of melt occurs.

Cylinder equipment:

• Standard screw


• Open nozzle

Wear resistant cylinder equipment is required for glass fibre

reinforced materials.

40 41



Polyacetal, POM

Structure:


Density:

1.41-1.42 g/cm3


Hard, stiff, tough, indestructible up to -40 °C, good heat resis-tance, good abrasion resistance, good frictional characteristics,low moisture absorption, non-toxic.

Chemical properties:resistant to

weak acids, weak alkaline solutions, petrol, benzene, oils,alcohol

not resistant tostrong acids


Highly flammable, bluish flame, drips and continues to burn,smells like formaldehyde.


Flange 40 - 50 °C / *50 °C

MH 1 160-180 °C/*180 °C

MH 2 180-205 °C/*190 °C

MH 3 185-205 °C/*200 °C

MH4 195-215 °C/*205 °C

DH 190-215 °C/*205 °C



Most favourable processing temperature around 210 °C.

Melt temperature:

205-215 °C


150 °C

Injection pressure:

1000-1500 bar.

For thick walled technical parts with a wall thickness of3-4 mm, injection pressure amounts to approx. 1000 bar;for thin-walled parts it can rise to approx. 1500 bar.


Dependent on the wall thickness of the moulding and on mouldtemperature. The longer the follow-up pressure, the less theshrinkage on the mouldings. Follow-up pressure should amountto approx. 800-1000 bar to achieve a pressure of around600-700 bar in the mould. Where precision mouldings are con-cerned, it is useful if injection and follow-up pressure are thesame (no drops in pressure). Extend follow-up pressure time forthe same total cycle time. Weigh mouldings until weight stabi-lises and optimum follow-up pressure time is established. Moreoften than not follow-up pressure time amounts to approx. 30%of the total cycle time. A moulding reaching 95% ideal weightshrinks by 2.3%. A moulding reaching 100% ideal weightshrinks by 1.85%. Slight, even shrinkage signifies consistantpart size.

Back pressure:

50-100 bar

Injection speed:

Average injection speed. If injection is too slow, pores appear

on the surface of the mouldings. If mould or melt temperature

is too low, the same thing happens.

42

• • • • •

43



Screw speed:

Max. equivalent to peripheral velocity of only approx. 0.7 m/sec.

Advisable to set it so that plasticising finishes just before cooling

time expires. Average screw torque required.


0.5-3.5 D dosing stroke.


2- 6 mm depending on dosing strode and screw diameter.

Pre-drying:

Not necessary. If material has become moist, dry for approx.4 hours at 100 °C.

Re-processing:

100 % for less important applications. Up to 20 % regrind

possible for precision parts.

Shrinkage:

Approx. 2 % (1.8-3.0)

Final shrinkage only determined after 24 hours.

Gating:

Pin gate can be used for small parts with uniform wall thickness.Select gate thickness to 50-60 % of the most concentrated wallthickness on the moulding. It is helpful to inject against some

form of resistance in the mould cavity (core, wall), because ofthe laminar flow. Processing with hot runner moulds is state ofthe art.

Machine shut-down:

Switch off heating and set back pressure to "0" 5-10 minutesbefore production ends. Purge cylinder. When overmouldingwith another material e.g. PA or PC, PE should be run throughin between, as it has a broad processing latitude.

44

Cylinder equipment:

• Standard screw

• Open nozzle


s i m a • • •

45



Polycarbonate, PC

Structure:

Amorphous

Density:

1.2g/cm3

Thermal, optical, mechanical properties:*

Hard, stiff, impact resistant up to -100 °C, good heat resistance,crystal clear, non-toxic, good pigmentability, low moistureabsorption, weather resistant.


resistant to

oil, petrol, dilute acids, alcohol

not resistant to

strong acids, alkaline solutions, benzene


Does not burn easily, sample extinguishes away from source ofheat, burns bright yellow, is smoky, chars, blisters, has notypical smell.


Flange 70- 90 °C / *80 °C

MH 1 230-270 °C/*250 °C

MH 2 260-310 °C/*270 °C

MH 3 280-310 °C/ *2 90°C

MH 4 290-320 °C /*290 °C

DH 300-320 °C/ *2 90°C


and for parts with a flow length/wall thickness ratio of between 50:1 and 100 :1.

46

Melt temperature:

280-310°C


200 °C

Injection pressure:

Very high injection pressures are needed, as material does not

flow well (1300-1800 bar).


Approx. 40-60 % of the required injection pressure. The lower

the follow-up pressure, the lower the stress in the mouldings.

Back pressure:

100-150 bar

Injection speed:

Dependent on flow length and wall thickness. Fast injection forthin-walled parts. If good surface quality is required, usestepped (slow-fast) injection speed.

Screw speed:

Max. 0.6 m/sec peripheral velocity. Adjust plasticising time

to suit cooling time. High torque is required on the screw.



Residual'melt cushion:


Pre-drying:

3 hours at 120 °C. Optimum mechanical properties if water

content is less than 0.02 %.

m m a §; ~ s

47



Re-processing:

Up to 20 % regrind can be mixed with virgin material. Heatresistance is also maintained if regrind quota is increased,but the mechanical properties deteriorate.

Shrinkage:

0.6-0.8 %

0.2-0.4 % glass fibre reinforced

Gating:

The diameter of the gate should correspond to at least 60-70 %of the most concentrated wall thickness on the moulding, but1.2 mm is the smallest gate diameter (gate - angle of cone 3-5°,on a good surface 2°). Pin gate can be used for smaller compo-nents with uniform wall thicknesses.

Machine shut-down:

Where breaks in production occur during the night, emptythe cylinder and drop temperatures to approx. 200 °C. Whencleaning the cylinder it is useful to inject through with high-viscosity PE. Draw the screw out of the heated barrel andremove residual material from the screw using a wire brush.

Cylinder equipment:

a Standard screw

B Non-return valve

• Open nozzle

48

Polymethyl methacrylate, PMMA

Structure:

Amorphous

Density:

1.18 g/cm3


Hard, brittle, very strong, scratch-proof, crystal clear, goodoptical quality, high gloss, extremely weather resistant, goodpigmentability, non-toxic.


resistant to

weak acids, weak alkaline solutions, fats and oils

not resistant to

strong acids and alkaline solutions, chlorinated hydrocarbons,risk of stress cracking


Highly flammable, burns brightly even when removed from

source of heat, crackling flame, rather smoky, sweet fruity

smell.


Flange 60- 80 °C / *70 °CMH 1 150-200 °C/*190 °C

MH 2 180-220 °C/*210°C

MH3 200-250 °C/*230°C

MH 4 200-250 °C /*230 °C

DH 200-250 °C /*230 °C



49



Melt temperature:

220-250 °C


170°C

Injection pressure:

High pressures needed due to poor flow characteristics

(1000-1700 bar).


Very long and high follow-up pressure needed (2-3 mins) forthick walled parts (lenses etc.). Follow-up pressure in generalamounts to 40-60 % of injection pressure.

Back pressure:

Relatively high back pressure required. 100-300 bar. Insufficient

back pressure causes gas bubbles in the moulding.

Injection speed:

Dependent on wall thickness and flow length. For thick walledarticles initial injection should be extremely slow to achieve per-fect frontal flow. Stepped injection speed (slow-fast) to obtaingood surface quality near the gate.

Screw speed:

Plasticise as slowly as possible according to cooling time.

Screw requires high torque, max. 0.6 m/sec peripheral velocity.





Pre-drying:

PMMA absorbs up to 1 % water. Pre-dry for 4 hours atapprox. 80 °C.

50

Re-processing:

Possible with properly pre-dried and pigmented material. Crystalclear regrind no longer produces parts with good optical quality.

Shrinkage:

0.3-0.7 %

Gating:

Large gates required, as material does not flow easily. For lenses,gate must be 0.5 mm smaller than wall thickness on the outeredge of the lenses. Smallest gate diameter - most concentratedwall thickness on moulding. To achieve good surface qualitynear the gate it is important to avoid sharp edges between thegate and the moulding. Short, round or square gate cross-sec-tion needed for good, long pressure transfer. Wide, thin gatesare not advisable.

Machine shut-down:

No other material is required to follow up.

Cylinder equipment:

• Standard screw; in some cases, special geometry


• Open nozzle

51



Polyphenylene oxide, PPO

Structure:

Amorphous

Density:

1.05-1.1 g/cm3


Hard, stiff, good frictional and abrasion characteristics, goodheat resistance, low water absorption, good scratch resistance,non-toxic.


resistant to

acids, alkaline solutions, alcohol, fats, oils

not resistant to

benzene, chlorinated hydrocarbons


Does not ignite easily, flame extinguishes away from source,

does not drip, smoky, luminous flame, pungent smell. PPO is

not transparent.


Flange 40- 60 °C / *50 °C

MH 1 240-280 °C/*250 °C

MH 2 280-300 °C /*280 °C

MH 3 280-300 °C /*280 °C

MH4 280-300 °C/ *2 80°C

DH 280-300 °C/*280 °C


and for parts with a flow length/wall thickness ratio of between 50:1 and 100:1 .

52

Melt temperature:

270-290 °C


200 °C

Injection pressure:

1000-1400 bar


40-60 % of injection pressure

Back pressure:

30-100 bar

Injection speed:

Mouldings with long flow paths require fast injection speed;

in such instances, however, it is important to ensure adequatemould venting.

Screw speed:

Average screw speeds. Max. peripheral velocity 0.6 m/sec.





Pre-drying:

2 hours at 110 °C

Re-processing:

Can be reprocessed as regrind providing the material has not

been charred.

53



Shrinkage:

0.8-1.5 %

Gating:

Pin/tunnel gate for small mouldings, otherwise sprue gate,

diaphragm gate, hot runner.

Machine shut-down:

Switch off heating; where screw back pressure is low, doseseveral times and purge cylinder.

Cylinder equipment:

• Standard screw


• Open nozzle

Acrylonitrile-butadiene-styrene + polycarbonate, ABS + PC

Structure:

Amorphous

Density:

1.15 g/cm3


Impact resistant, high gloss, light resistant, electroplatable, heat

resistant, good fracture resistance.

Chemical properties:resistant to

limited hydrolysis resistance

not resistant to

ketone, ester, chlorinated hydrocarbon


Flange 50 - 70 °C / *70 °C

MH 1 230-250 °C / *250 °C

MH 2 250-260 °C / *260 °C

MH 3 250-270 °C / *265 °C

MH 4 250-270 °C / *265 °C

DH 250-270 °C / *270 °C* These temperature profiles are valid for stroke utilisation of between 35 and 65 %


Melt temperature:

260-270 °C


200 °C

Injection pressure:

800-1500 bar




Approx. 40-50 % of the required injection pressure in order toavoid sink marks appearing. Follow-up pressure must be set aslow as possible to produce low-stress mouldings.

Back pressure:

Only around 50-100 bar in order to avoid frictional heat.

Injection speed:

Average injection speed (up to 60 mm/sec) to keep frictionalheat down. Partially stepped - slow-fast.

Screw speed:

Max. screw speed corresponding to approx. 0.4 m/sec

peripheral velocity.


1.0-3.0 D dosing stroke because the melt is susceptible to

overheating or because of excessive melt dwell time in the plas-ticising cylinder. Dwell time for the melt in the cylinder shouldnot exceed 6 mins.


2-5 mm depending on screw diameter and dosing stroke.

Pre-drying:

4 hours at 80 °C.

Re-processing:

Up to 20 % regrind can be added, provided it has been properlypre-dried and is not charred. It is better to use regrind for partswhere strength requirements are not so stringent.

56

Shrinkage:

Shrinkage is almost identical in all axes and amounts to0.5-0.7 %; 0.2-0.4 % on glass reinforced types.

Gating:

Any recognised type of gate can be used. When injecting viahot runner, temperature in the hot runner must be accuratelycontrolled.

Machine shut-down:

Switch off heating. Purge cylinder.

Cylinder equipment:

• Standard screw up to 50 mm diameter. Where larger screwdiameters are concerned, use screw with lower compressionand shorter metering section.


• Open nozzle

57



Polybutylene terephthalate, PBTP

Structure:


Density:

1.30 g/cm3


Good heat resistance, good stiffness and hardness, low waterabsorption, good resistance to stress cracking, excellent fric-tional characteristics and abrasion resistance, good dimensionalstability, non-toxic.


resistant to

oils, fats, alcohol, ether, petrol, weak acids, weak alkalinesolutions

not resistant to

benzene, alkalis, strong acids, strong alkaline solutions, ketone


Material does not ignite easily, extinguishes when removed fromflame, luminous flame, yellowy orange, smoky, slightly sweetaromatic smell.


Flange 50 - 70 °C / *70 °C

MH 1 230-250 °C /*240 °C

MH 2 240-260 °C/*250 °C

MH 3 250-260 °C/*260 °C

MH 4 250-260 °C/*260 °C

DH 250-260 °C/*260°C



Melt temperature:

250-260 °C, narrow processing range

below 240 °C danger of freezing

above 270 °C material becomes charred


210 °C

Injection pressure:

Injection pressure of 1000-1400 bar can result. Follow-uppressure should amount to 50-60 % of the resulting injectionpressure.

Back pressure:

Only approx. 50-100 bar in order to avoid frictional heat.

Injection speed:

Fast injection speeds are required because of melt setting

speed and the rate of crystallisation. Cooling or setting of themelt during injection must be avoided. Ensure mould is wellvented, otherwise there will be signs of charring at the end ofthe flow path as a result of compressed air.

Screw speed:

Max. screw speed corresponding to approx. 0.7 m/secperipheral velocity.

Recommended min, and max. dosing stroke:

0.5-3.5D dosing stroke because melt is susceptible to over-heating or because of excessive melt dwell time in the plasticis-ing cylinder. Dwell time for the melt in the cylinder should notexceed 5 mins.



Pre-drying:

4 hours at 120 °C.

58 59



Re-processing:

Up to 10 % regrind can be added for material types containing

flame retardants, providing the material has not been charred

and has been properly pre-dried. Up to 20 % for material types

without flame retardants.

Shrinkage:

Very dependent on mould temperature. The higher the mould

temperature, the greater the shrinkage - 1-.4-2.0 %.

0.4-0.6 % for 30 % GF.

Gating:

Do not use concentric sprue or pin gate with glass fibre rein-

forced materials. Injection point should be selected so that the

cavity is filled evenly. When gating via hot runner, temperature

must be accurateiy controlled in the hot runner.

Machine shut-down:

Switch off heating. Empty cylinder. During breaks in productionand before restarting the machine, squirt the melt out until it is

free from bubbles.

Cylinder equipment:

• Standard screw

s Non-return valve

• Open nozzle

Polyethylene terephthalate, PETP

Structure:


Density:

1.35 g/cm3


Good impact strength, extreme hardness and stiffness (slightlymore so than PBTP), good dimensional stability, low water

absorption, only slight internal stress, good flowability.


resistant to

oils, fats, alcohol, ether, petrol, weak acids, weak alkaline

solutions

not resistant to

benzene, alkalis, strong acids, strong alkaline solutions, ketone


The material is difficult to ignite, extinguishes away from flame,

luminous flame, yellowy orange, smoky, slightly sweet aromatic

smell.


Flange 50- 70 °C / *70 °C

MH 1 240-260 °C/*250 °C

MH 2 240-260 °C /*250 °C

MH3 250-290 °C/ *2 70 °C

MH 4 250-290 °C/*270 °C

DH 250-290 °C /*270 °C



60 61



Melt temperature:

270-280 °C


220 °C

Injection pressure:

For thin walled articles, injection pressure up to 1600 bar canresult.


Approx. 50-70 % of the required injection pressure in order to

avoid sink marks. Set follow-up pressure time only for as long

as is necessary. With amorphous materials in particular, exces-

sive follow-up pressure times cause increased stress, which

reduces the impact strength of the mouldings.

Back pressure:

Only around 50-100 bar in order to avoid frictional heat.

Injection speed:

Fast injection speeds are required because of melt settingspeed and the rate of crystallisation. Cooling or setting of themelt during injection must be avoided. Ensure mould is wellvented, otherwise there will be signs of charring at the end ofthe flow path as a result of compressed air.

Screw speed:

Max. screw speed corresponding to approx. 0.7 m/secperipheral velocity.


0.5-3.5 D dosing stroke because melt is susceptible to over-heating or because of excessive melt dwell time in the plasticis-ing cylinder. Dwell time for the melt in the cylinder should notexceed 5 mins.

62



Pre-drying:

4 hours at 140 °C.

Re-processing:

Max. 20 % regrind can be added providing it has not beencharred and has been properly pre-dried. Not possible to

achieve the same tensile, flexural and impact strength as whenvirgin material is used.

Shrinkage:

Varies greatly depending on material type, wall thickness, mould

temperature, follow-up pressure and follow-up pressure time -

1.2-2.0 %, or 0.4-0.6 % with 30 % GF.

Gating:

Any weil-known type of gate can be used. When injecting viahot runner, temperature in the hot runner must be accuratelycontrolled.

Machine shut-down:

Switch off heating. Empty cylinder. When changing to another

thermoplastic material it is advisable to flush through with PE

or PP beforehand.

Cylinder equipment:

• Standard screw

a Non-return valve

63



Cellulose acetate, CA

Structure:

Amorphous

Density:

1.2-1.3 g/cm3


Tough, resistant to boiling water, difficult to break, good scratchresistance and self-polishing effect, low electrical charging,non-toxic, good surface gloss. The strength of this material

makes it suitable for embedding metal parts (screw driver).


resistant to

oils, fats, benzene, petrol

not resistant to

vinegar, acids, alkaline solutions


Does not ignite easily, extinguishes away from flame, smoky

with greenish yellow flame, smells of burnt paper and vinegar.


Flange 30- 40 °C / MO °C

MH 1 140-160 °C/*150 °CMH 2 160-185 °C/ *170 °C

MH 3 170-200 °C/ *180 °C

MH 4 170-200 °C/ *180 °C

DH 170-200 °C/ *180 °C



Melt temperature:

200-210 °C

Colour change in the melt indicates that melt temperature is too

high. If melt temperature is too low, surface gloss and transpar-

ency deteriorate.


160°C

Injection pressure:

800-1200 bar


40-70 % of the injection pressure. Not too high if internal stress

is to be avoided. Relatively long follow-up pressure for thick

walled parts.

Back pressure:

50-100 bar

Injection speed:

Fast injection speed for thin walled parts. Inject slowly for thick

walled parts.

Screw speed:

Average screw speed, corresponding to max. 0.6 m/secstarting speed.





Pre-drying:

3 hours at 70 °C.

64 65



Re-processing:

Up to 20 % regrind can be added, providing it has not beencharred and is properly pre-dried.

Shrinkage:

0.4-0.7 %

0.4 % in direction of flow

0.6- 0.7 % across the direction of flow

Gating:

Pin/tunnel gate. Avoid jetting by spring actuated auxiliary core,otherwise surface defects will occur near the gate.

Machine shut-down:

Switch off heating. Plasticise several times without backpressure and squirt melt out.

Cylinder equipment:

• Standard geometry, in some cases special geometry

a Non-return valve

• Open nozzle

Polyvinyl chloride unplasticised, PVC-U

Structure:

Amorphous

Density:

1.35 g/cm3


Stiff, hard, transparent to opaque, good bonding properties,certain formulations non-toxic.


resistant to

acids, alkaline solutions, oils, fats, petrol

not resistant to

benzene, ketone, ester, stain removers


Does not ignite easily, smoky, burns green, sputters, smells ofhydrochloric acid, self extinguishing.


Flange 30- 50 °C / *50 °C

MH 1 140-160 °C/*150 °C

MH 2 165-180 °C/*170 °CMH 3 180-210 °C/*190°C

MH 4 180-210 °C/*200°C

DH 180-210 °C/*200°C



Melt temperature:

210-220 °C




120 °C

Injection pressure:

800-1600 bar


Do not set too high. 40-60 % of injection pressure to suit themoulding and the gate.

Back pressure:

It is very important with PVC to select the right setting, because

the material is heat sensitive. Heat from the friction of the screw,

when properly directed, is better than heat from the cylinder

heater bands. Back pressure up to 300 bar is possible.

Injection speed:

Do not set too high. Make sure that the material has not

sheared. For this reason, stepped injection is advisable.

Screw speed:

Set as low as possible, corresponding to max. speed 0.2 m/secperipheral velocity. With long cooling times and despite slowscrew speed, delayed plasticising can be used to ensure thatdosing finishes just before cooling time expires. High, eventorque is required.




1-5 mm depending on dosing stroke and screw diameter. Keep

cushion small and make sure axial screw clearance is minimal.

Pre-drying:

1 hour at 70 °C (only necessary if material has not been storedproperly).

Re-processing:

Can be reused providing material has not been charred.

Shrinkage:

0.5-0.7 %

Gating:

Sprue, film and diaphragm gates advisable. The gate must beradiused towards the moulding. Pin gate possible for smallparts.

Machine shut-down:

Switch off heating. Plasticise without back pressure, let the meltstand for 2-3 minutes and then squirt it out slowly. Repeat the

process until cylinder temperature has fallen to 160 °C, thenempty the cylinder.

Cylinder equipment:

• Screw geometry for rigid PVC

B Flighted or unflighted screw tip

• Open nozzle

.

68 69



Polyvinyl chloride plasticised (PVC-P)

Structure:

Amorphous

Density:

1.1-1.4 g/cm3


The material is flexible, rubbery-elastic, non-toxic.


resistant to

acids, alkaline solutions, detergents ,oils, fats

not resistant to

petrol, ester, chlorinated hydrocarbons


Does not ignite easily, smoky, burns green, sputters, smells of

hydrochloric acid with plasticiser.


Flange 30- 50 °C / *50 °C

MH 1 140-160 °C/*150°C

MH 2 150-180 °C/*16 5 °C

MH 3 160-220 °C/*180 °C

MH 4 160-220 °C/*190 °C

DH 160-220 °C/*200 °C



iS B

70

Melt temperature:

200-220 °C


120 °C

Injection pressure:

800-1200 bar


30-50 % of the necessary injection pressure.

Back pressure:

50-100 bar

Injection speed:

Do not inject too fast if good surface quality is required -

(stepped injection, perhaps).

Screw speed:

Set average screw speed; max. equal to 0.5 m/sec peripheral

velocity.





Pre-drying:

1 hour at 70 °C (only if material has not been properly stored).

Re-processing:

Can be reused providing material has not been charred.

Shrinkage:

1-2.5 %

71



Gating:

The gate must be radiused towards the moulding. Pin gatepossible for small parts.

Machine shut-down:

Switch off heating. Plasticise several times without backpressure and squirt melt out.

Cylinder equipment: *

• Standard screw

• Open nozzle


72 73



4.2 Distinguishing characteristics of plastics 1

" • . MaterialDistinguishing characteristics __^

Appearance

Fracture

Float test

Burn test

Flame

Smell during burn test

Finger nail scratch test

transparent/opaque

crystal clear

no fracture

stress-whitening/tough

brittle fracture

floats

sinks

highly flammable

slow to ignite

self-extinguishing

continues to burn

smoky

not smoky

drips

does not drip •

luminous yellowbright with blue core

bluish

greenish/yellow

waxy/paraffin

burnt bone

slightly sweet

tar-like

pungent/formaldehyde

like fishike paper and vinegar

like styrene

fruity

like hydrochloric acid

not typical

scratch-proof

not scratch-proof

PE

X

X

X

X

X

X

X

X

X

X

pp

X

X

X

X

X

X

X

X

X

X

X

PS

X

X

X

X

X

X

X

X

X

X

SAN

X

X

X

X

X

X

X

X

X

X

X

ABS

X

X

X

X

X

X

X

X

X

X

POM

X

X

X

X

X

X

X

X

X

X

X

PMMA

X

X

X

X

X

X

X

X

X

X

PA

X

X

X

X

X

X

X

X

X

X

74 75



—;Distinguishing characteristics

Appearance

Fracture

Float test

Burn test

Flame

Smell during burn test

Finger nail scratch test

Material

transparent/opaque

crystal ctear

no fracture

stress-whitening/tough

brittle fracture

floats

sinks

highly flammable

slow to ignite

self-extinguishing

continues to burn

smoky

not smoky

drips

does not drip

uminous yellowbright with blue core

bluish

greenish/yellow

waxy/paraffin

burnt bone

slightly sweet

tar-like

pungent/formaldehyde

ike fishlike paper and vinegar

like styrene

fruity

like hydrochloric acid

not typical

scratch-proof

not scratch-proof

PC

X

X

X

X

X

X

X

X

x

X

CA

X

X

X

X

X

X

X

X

X

PPO

X

X

X

X

X

X

X

X

X

PETP

X

X

X

X

X

X

X

X

X

X

PBTP

X

X

X

X

x

X

X

X

X

X

ABSPC

X

X

X

X

X

X

X

X

X

PVC-U

X

X

X

X

X

X

* X

X

X

X

X

PVC-P

X

X

X

X

X

X

X

X

X

X

Si iSS

76

s ill a ill if isi iii ::.

77

4.2 Distinguishing characteristics of plastics 2



Optimizarea procesului la o

masina de injectie mase plastice

Principii:

1. Cand se optimizeaza parametrii este foarte important sa nu

se modifice mai mult de un parametru odata, pana cand nu se

realizeaza efectul acelui parametru asupra calitatii produsului

Sunt multe schimbari ce pot fi facute asupra parametrilor iar

influenta acestora apare imediat.

2. Optimizarea trebuie sa inceapa intotdeauna cu calitatea

injectiei in minte. Legaturile fundamentale dintre caracteristicile

calitatii si setarea parametrilor , sunt suficient de bine cunoscute.

(vezi diagrama in pagina alaturata). Este important sa realizatio evaluare atenta a caracteristicilor calitatii si ale limitelor acesteia.

Apoi stabilitatea si calitatea procesului trebuie optimizata

pe baza parametrilor si a distributiei curgerii.Numai dupa ce

acestea au fost realizate se poate face optimizarea timpului de ciclu .

3. In sistemul de control NC4 exista o pagina pentru optimizarea

procesului, pagina unde sunt comasati toti parametrii importanti.Toti pasii esentiali pentru optimizare pot fi modificati in aceasta pagina.Afisate in aceasta pagina sunt si toate valorile ACTUALE relevante.

Un sistem integrat de achizitii de date este disponibil pentru a permite

operatorului sa optimizeze profilele de presiune hidraulica sipresiune in cavitate pentru fazele in care efectul asupra calitatii

este semnificativ si decisiv.

Parametrii importanti pentru optimizarea procesului pot fi considerati

urmatorii:

1. Temperatura cilindrului de plastifiere si a topiturii

2. Temperatura matritei

3. Viteza de injectie

4. Volumul de comutare5. Timpul de mentinere in presiune

6. Presiunea de mentinere

7. Timpul de racire

8. Viteza de dozare

9. Contra-presiunea

10. Decompresia (retragerea snecului)

11. Monitorizarea parametrilor

5.1 Corelatia dintre caracteristicile calitatii si parametrii de

proces prezentate ca profil al presiunii in cavitate

80 81

Suprafata

(rugozitate, stralucire, culoare)structura, orientare la suprafata,

cristalinitate

definire contur

formare structura,greutate,deviatiidimensionale

greutate, deviatii dimensionale

contractie , goluri in structurastriatii, orientare

interna

Viteza de injectie

Temperatura

Temperatura matritei

punctul decomutaretemperaturacilindrului

temperaturamatritei

presiunea de mentinere

timpul presiunii de mentinere

temperatura cilindrului

temperatura matritei

Timpul de injectie

Presiunea integrala de injectie

Temperatura topiturii

Temperatura matritei

presiunea max.hidr. sau a cavitati

presiunea integrala in cavitate

temperatura topiturii

temperatura matritei

Faza de Injectie Faza de Faza de Mentinere in presiunecompresie .



1. Temperatura cilindrului de plastifiere si a topiturii

Temperaturile pre-setate ale cilindrului, impreuna cu forta de frecare

indusa de viteza snecului, asigura caldura suficienta pentru a

topi materialul plastic (plastifiere).

Recomandarile de setare pot fi gasite in datele de setare individuale

ale materialelor (vezi Capitolul 4 al carticelei).

Valabil pentru toate materialele:

Temperatura topiturii prea mare:

• Degradare termica

• Diferente de culoare / schimbare de culoare

• Contractie marita / variatii dimensionale

• Prelungirea timpului de racire

• Proprietati mecanice inferioare

Temperatura topiturii prea mica:

• Topitura neomogena

• Tensionare ridicata in piesa injectata

• Presiunea de injectie necesara este ridicata• Liniile de curgere si cele de imbinare sunt clar vizibile

Uzual, temperaturile cilindrului sunt setate in profil crescator

(exceptie: PA). Primele doua zone de incalzire (MH1 si MH2)strebuiesc setate la limita inferioara deoarece acolo este cursa cu

utilizare minima si la limitele superioare pentru cursele intens utilizate.

82

2. Temperatura matritei

Temperaturile matritei asigura curgerea libera a materialului

pana ce cavitatea este complet umpluta.

Recomandari pentru setarea temperaturilor matritei poti fi

gasite in Capitolul 4.3 al acestei carticele.

In principiu:

O temperatura mare a matritei asigura:

• Contractie post-injectie redusa• Orientare redusa, tensionare interna mica

• Necesita presiune scazuta

• Cristalinitate crescuta

Temperatura prea mare a matritei:

• Timp de racire prelungit (2%/1 °C)

• Deviatii dimensionale

Temperatura prea mica a matritei:

• Suprafata mata• Efect de unda

• Linii de curgere / linii de imbinare vizibile clar

• Tensionare crescuta in piesa injectata

O unitate de control al temperaturii de inalta performanta se

poate folosi pentru a mentine temp. constanta in matrita . Temp.

matritei este unul din cei mai importanti parametrii si trebuie mentinut

in limite de toleranta foarte stranse. Pentru piese cu proprietati de

contractie (ex. piese tehnice), este recomandat sa se foloseasca

unitati de control temp. integrate, ale carei valori setate pot fimemorate si monitorizate de catre IBED (ErgoControl).

83



Re. 3 Viteza de injectie

Viteza de injectie influenteaza rata de dispersie a topiturii in

matrita. In principiu, trebuie setata cat de rapid posibil.

In cazul pieselor cu variatii in grosimea peretilor poate fi necesar

setarea unui profil in trepte. In faza start si, respectiv, sfarsit de

umplere poate fi nevoie de un profil ascendent si,respectiv, descendent.

Viteza de injectie prea mare:

• bavura

• defecte de suprafata langa duza

• arsuri la capatul caii de curgere

• necesar de forta de inchidere mare

Viteza de injectie prea mica:

• efect de unda

• piesa umpluta partial

• deformare

• linii de imbinare vizibile

Inainte de toate, monitorizarea presiunii trebuie setata la maximum pentru

a optimiza viteza de injectie. Cand presiunea de injectie limita este atinsa,aceasta este indicata in ecranul de achizitii de date, se datoreaza faptului

ca a fost schimbata viteza de injectie (valorile setate) iar timpul de injectie a

ramas neschimbat.

84

Re. 4 Comutare in functie de volum (punct de comutare)

Comutarea pe presiune de mentinere reprezinta tranzitia de la

reglajul dependent de viteza din timpul injectiei la reglajul dependent

de presiune din timpul fazei de mentinere in presiune .

In general, comutarea trebuie sa aiba loc atunci cand aprox. 95 %

din volumul cavitatii a fost umplut. La piesele cu pereti subtiri poate

fi necesar sa se umple chiar 98 % din volumul cavitatii.

Comutare prea devreme:

• urme specifice de comutare

• cavitate umpluta incomplet

• supturi

• subdimensionare

• urme pe liniile de imbinare

Comutare intarziata:

• bavura


• supradimensionare• probleme la demulare

• tensionare ridicata in piesa injectata

La inceput trebuie selectat un punct de comutare devreme. Gradual

acesta se seteaza intarziat (studiu al umplerii mattritei) pana ce

umplerea volumului este aproape realizata. Aceasta procedura

furnizeaza informatii valoroase cu privire la profilul frontului de curgere

in matrita si descoperirea urmelor de curgere si de imbinare.

85



Re. 5 Timp de mentinere in presiune

Dupa umplerea volumetrica, contractia este stabilizata in timpul

mentinerii in presiune prin racirea cavitatii matritei.

Timpul de mentinere in presiune se seteaza ca durata necesara

topiturii sa se solidifice langa duza.

Timp de mentinere in presiune prea lung:

• timp rezidual insuficient ramas pentru plastifiere

• consum de energie crescut

Timp de mentinere in presiune prea scurt :

• supturi, goluri

• variatii in greutate a pieselor

• subdimensionare

• topitura curege inapoi in cilindru

• fluctuatii ale pernei de material

Pentru stabilirea timpului optim de mentinere in presiune cresteti

continuu valoarea setata pana ce piesele, fara culee, nu mai cresc in

greutate. Concluzie: Determinarea timpului optim de mentinere inpresiune se face prin controlul greutatii.

0 2 4 6 8 1 01 2 1 4 1 6 Timp de mentinere (s)

86

i

Re. 6 Presiunea de mentinere

Presiunea de mentinere este presiunea hidraulica activa pe

durata timpului de mentinere si are menirea de a combate

formarea urmelor de tip suptura.

De regula, presiunea de mentinereeste de 30-50 % din

presiunea necesara de injectie.

Presiunea de mentinere prea mare:

• bavura


• tensionare ridicata in piesa injectata

• supradimensionare

• probleme la demulare

• urme de ejector

Presiunea de mentinere prea mica:

• supturi, goluri

• subdimensionare

• contractie mare de volum• fluctuatii mari in greutate

Re. 7 Timp de racire

Timpul de racire reprezinta perioada finala de racire a piesei

in cavitate pana ce se atinge stabilitatea dimensionala suficienta

pentru demulare. Caracteristicile urmarite aici sunt dimensiunile si

deformarea pieselor .

Timp de racire prea lung:• creste timpul de ciclu

Timp de racire prea scurt:

• deformare

• urme de aruncator

• creste contractia post-injectie

Verificati si Capitolul 5.2 - Calculul timpului de racire.

87



Re. 8 Viteza de rotatie a snecului

Viteza snecului este responsabila pentru plastifiere, adica pentru

pregatirea termica, mecanica si omogenizare a materiei prime.

Limita superioara setata a vitezei snecului este forta periferica

maxima admisa de snec pentru diferite tipuri de material. Timpul de

dozare rezultat, nu trebuie sa fie cu mult mai scurt decat timpul de

racire, asta pentru a se realiza o plastifiere cat mai delicat posibil.

.

Viteza de rotatie prea mica:

• fluctuatii ale timpului de ciclu (in cazul t doz> t r a c i r e )

Viteza de rotatie prea mare:

• degradare termica si mecanica a materialului

• diferente mari ale temperaturii topiturii dealungul lungimii snecului

• creste uzura snecului si a valvei non-retur

Re. 9 Contra-presiunea

Contra-presiunea reprezinta presiunea din fata toprilei, impotriva careiasnecul trebuie sa lucreze pe parcursul dozarii.

Contra-presiune prea mare:

• degaradarea materialului datorita frictiunii excesive

• capacitate redusa de plastifiere, timp lung de dozare

Contra-presiune prea mica:

• neomogenitate a topiturii

(fluctuatii mecanice si termice)

• granule de material netopit

• bule de aer

88

Re. 10 Decompresiea (retragerea snecului)

Decompresia serveste la reducerea presiunii topiturii in spatiul

din fata snecului, dupa dozare. Trebuie sa fie aprox. 4 % din

volumul de dozare dar, ca valoare, sa nu fie mai putin de 10 %

din diametrul snecului. Pentru mai multe detalii vezi Capitolul

4.1 "Indrumar de procesare pentru cele mai importante

materiale plastice".

Decompresie prea mare:

• bule de aer in jurul punctului de injectie

Decompresie prea mica:

• scurgeri de material pe la duza sau duze calde

Re. 11 Parametrii de monitorizare

Parametrii pentru monitorizare se regleaza numai dupa ce toti

parametii importanti au fost optimizati si nivelul de calitate este

constant mentinut in limitele de toleranta.

a) Monitorizarea injectiei (limitarea presiunii de injectie)

In timpul fazei de umplere exista o dependenta intre pres.hidr.

si viteza de injectie setata, dependenta co relata cu rezistenta

la curgere a topiturii. In situatii normale acest profil de presiune

este repetitiv. Aceasta presiune poate creste involuntar numai

daca o defectiune are loc in timpul procesului sau daca unul

dintre parametrii fluctueaza.

Din acest motiv, presiunea de injectie limita este setata aprox.

10-15 % peste presiunea maxima de umplere. Daca aceasta

este depasita, apare un mesaj de eroare si masina se opreste

fara sa afecteze in nici un fel matrita sau duzele calde.

b) Monitorizarea injectiei

Deasemeni, in timpul fazei de umplere apare si un timp actual

de injectie dependent de viteza de injectie setata. Devierile

evidente de la acest timp inseamna o eroare in proces. Limita

timpului de injectie trebuie setata cu aprox. 10-15 % peste

timpul actual de injectie.

89



Typical pressure profile during mould filling

Pressure (p)

Injection pressure monitoring

Change-over

Time (t)

90

5.2 Cooling time

Cooling time is calculated using the following formula:

cooling time

wall thickness

For an initial estimate of cooling time with the aid of a diagram,the cooling time equations can be grouped according to thedifferent plastics. These groups are determined by taking asa basis the average temperatures for melt, cavity wall and de-moulding. (Compare with Chapter 4.1 "Processing guidelinesfor plastics".)

Changes in melt temperature have no appreciable effect withwall thicknesses up to 4 mm (< 1 sec).

Changes in cavity wall temperature, on the other hand, must

be taken into consideration.

91

with

effective thermal diffusivity

melt temperature

mean demoulding temperature

average cavity wall temperature (average valuederived from minimum and maximum cavitywall temperature over the course of an injectionmoulding cycle)



s = wail thickness [mm]

tcoo! = cooling time [sees]

Notes on producing the cooling time diagram

Control equations:

PC: toool = 2 .17x s

PA6, PBTP, LDPE tcool = 2.64 x s

ABS, PS, SAN, PA 6.6:t0OOl = 2.82 x s2

HDPE, PMMA toool = 3.00 x s2

PP tcool = 3.67 x s2

POM toool = 4.18xs2

The curve points for the different groups of plastics are given in

the following table. These curve points are also entered on the

two subsequent diagrams, where s = 1 to 2.5 mm and s = 2.5

to 4 mm.

Wall thickness

Change in cavity walltemperature by [°C]

Change in cooling timeby [sees.]

s = 2 mm

+10

+5

+5

+2

-5

-1.2

-10

-2

s = 4 mm

+10

+20

+5

+7.5

-5

-5

-10

-9

Influence of cavity wall temperature on cooling time with

wall thicknesses of 2 and 4 mm

92

5.2 Cooling time as a function of wall thickness (1 to 2.5 mm)

93



5.2 Cooling time as a function of wall thickness (2.5 to 4 mm)

The correct evaluation and selection

of process parameters for quality



p p q y

assurance in injection moulding

Ever shorter innovation cycles, the growing complexity of pro-ducts and increasingly stiff competition all call for economicinjection moulding production. Quality assurance and the abilityto reduce scrap to a minimum are becoming increasinglyimportant.

Only those processors who can accurately predict the output of

perfect mouldings will have costs under control, be able to meet

delivery deadlines and be acknowledged as reliable partners.

When it comes to quality control, the control and analysis

features on modern injection moulding machines are highlyefficient. The operator can have complete control over theproduction process, carry out long-term statistical evaluationsor anticipate trends.

Of course, to make best use of these resources the setterneeds to know which machine and process parameters influ-ence the quality of a moulding - and, most importantly, to whatextent.

Practice shows, however, that the significance of these para-

meters varies from application to application and is determinedby the demands of the particular moulding.

The following report and data tables are the result of extensivelong-term testing and the evaluation of a large number of indi-vidual cases. They assist in the selection and evaluation of thecorrect parameters and in defining the required tolerances forquality control on the machine.



The table opposite (Fig. 6.1) shows the 5 most significant qualitycharacteristics and their relative importance for the productionof different product groups. For technical precision parts, dimen-sional stability is clearly of greatest importance, while for opticalparts, for example, surface quality and melt homogeneity arecrucial factors.

Of course, there are still a good many other quality characteris-tics -the "inherent properties", for example, like molecularweight, orientation on the skin and the core, dispersion of fillers

and reinforcing materials etc. These selected criteria, however,represent essential performance properties which can also besubjected to direct and mainly non-destructive testing.

At this point, of course, there is still no indication of whichparameters are required for controlling the quality of themouldings.

Fig. 6.1



Fig. 6.2 shows important process parameters and their relationto the various quality characteristics. The correlation between

machine or setting parameters and the characteristics of the

mouldings is sometimes very complex. In almost all instances,

there are several setting parameters relating to a single quality

characteristic, which is why more than one parameter needs tobe controlled.

Fig. 6.2

ft ill • • • • • • • Si 81 Si



Fig. 6.3 illustrates the connection between quality characteristicsand process parameters with the aid of the (integral) cavitypressure profile. It shows clearly how the majority of qualitycharacteristics are influenced during the follow-up pressurephase. Consequently, the cavity pressure profile must fall withinspecified tolerance limits during this phase. The diagram alsoshows those setting and monitoring parameters relevant toquality. The cavity pressure profile, mould temperature and melttemperature are the most significant and informative factorshere.

In 50 % of all cases cavity pressure monitoring proves very use-ful from a processing point of view, but it is only realistic in 3 %of these, since the cost in terms of machine, mould and per-sonnel is relatively high. Cavity pressure monitoring is appliedto around 20 % of mouldings, predominantly technical precisionand functional components, optical products and automotiveparts.

The use of cavity pressure enables the setting parameters forthe machine and peripheral equipment to be largely indirectly

monitored, because the smallest changes or disruptions - tomould or melt temperature, to the function of the non-returnvalve, to the change-over point to follow-up pressure or to thebatch of material - all have an effect on cavity pressure. Veryoften it is possible to monitor several settings via one singleparameter and also to document them in accordance withDIN ISO 9000.

The time profile for cavity pressure can be divided into threephases. These are the injection, compression and follow-up

pressure phases.

In the injection phase cavity pressure is determined mainlyby flow resistance, viscosity of the moulding compound andinjection speed. During the compression phase the melt iscompressed up to the so-called change-over point, which theninitiates the follow-up pressure phase. In this latter phase, thepressure rises in the mould initially, because the mould is nowcompletely filled. As the melt cools down, so the pressure fallsslowly. In conjunction with the cooling process, this phase isdecisive in terms of shrinkage and internal orientation, and alsofor crystallisation in partially crystalline materials.

Fig. 6.3

• • • • • • • • • •

01

Si Si Si Si it Hi i ii f ! Si • • •



Pressure transducers have been used in the mould for morethan 20 years and at the moment are probably the simplestform of total control, without directly including the characteris-tics of the moulded part. Care should be taken to ensure thatthe cavity pressure sensor is located at a quality-determiningpoint - as close to the sprue as possible - approx. 30-40 % ofthe way along the flow path. A pressure sensor can also beintegrated in the hydraulic circuit (in or on the hydraulic injectioncylinder).

Fig. 6.4 shows a characteristic profile of hydraulic and cavitypressure. If, for example, the hydraulic pressure (upper curve)rises during the injection phase as a result of a lower mouldtemperature (caused by increased flow resistance during injec-tion), then cavity pressure falls - (with hydraulic pressure remain-ing constant during the follow-up pressure phase) - due to thereduced pressure transfer performance of the low-viscositymelt. The result is a lower integral cavity pressure. If it were onlythe hydraulic pressure being monitored, no indication would begiven as to the quality of the mouldings. The rise in hydraulicpressure during the injection phase would indeed be noticeable,but the effects of this increase once change-over has occurredcould not be monitored, since hydraulic pressure during thisphase is regulated at a constant level. By selecting integralcavity pressure with suitable integral limits, however, the quality-related phases can be accurately monitored.

The most important factors for technical precision parts aredimensional stability, melt homogeneity and low warpage, whichmeans that the parameters for monitoring must be selectedfrom relevant phases in the process. Dimensional stability and

warpage are mainly influenced during the follow-up pressurephase, which is why integral cavity pressure is particularlysuitable.

Changes in melt homogeneity occur during the dosing phasedue to fluctuations in screw speed and/or back pressure, andthese can be diagnosed by monitoring the above-mentionedparameters. Where particularly sensitive materials are con-cerned, the dosing operation can also be monitored via thescrew load.

Fig. 6.4

104 105



Selection criteria

On the assumption that the machine has been optimally setprior to the start of the production cycle, the following selectioncriteria have emerged in the course of daily practice for the8 most significant process parameters which need to be keptconstant.

In general, cycle time says little about component quality,apart from when processing thermally sensitive materials insemi-automatic operation.

Consistent injection time is important for short injection timesand for parts with stringent surface requirements.

Ideally, a constant dosing time should be observed, particularlywhen processing (plasticising) material blends (LDPE-HDPE),blends for automotive parts and regrind. It is also importantwhere irregularities occur during plasticising as a result of thematerial (PA-PMMA), and when colouring using pigment pasteor masterbatch.

A decreasing melt cushion when processing with filled materials

indicates wear on the non-return valve. Fluctuations are often asign of inhomogenous melt. Where there is only very slight fluc-tuation in the melt cushion and the non-return valve is function-ing correctly, the dimensions of the moulded part will thenremain constant. For products with relatively dense wall thick-nesses requiring a correspondingly long, high and uniformfollow-up pressure profile, integral cavity pressure is the firstchoice.

Maximum cavity pressure is informative for products withsmall wall thicknesses and a short follow-up pressure time orhigh injection pressure.

Melt temperature is important for thermally sensitive materials.This is equally so for materials with a narrow processing rangeor for materials whose properties change at the slightest varia-tion in temperature.

Finally, accurate mould temperatures are required, particularlywhen processing any of the engineering materials (PC, PA,POM, PMMA ...), for example, for the production of opticallenses in PMMA or gear wheels in POM.

In order to be able to put these findings to practical use, it isnecessary first of all to evaluate the relative importance of the

individual process parameters for the different product groups

and to establish the tolerances.

Fig. 6.5 summarises the selection criteria and also evaluates theextent of the influence of the individual process parameters onthe quality of the various product groups. The quality character-istic here is the percentage weight fluctuation which can beachieved on the mouldings. The data shown is a recommen-dation as to the level of quality to which the mouldings in thedifferent product groups can be manufactured.

" 1 " denotes a parameter with the largest influence on quality,while "8" denotes minimum influence. These should not, how-ever, be seen as absolute values for comparison between thevarious product groups, but as being based on a specificcharacteristic value for each product group.

Fig. 6.6 goes one step further by showing the permissible per-centage deviations (+/- tolerances) for each of the parameters.The variation in values is as a result of varying processing con-

ditions for the respective products. For example, the mouldtemperature for technical functional parts is around 80 °C, whilefor high speed precision parts it is only 25 °C. Thus, when con-verted to absolute values, the permissible deviations are almostidentical.

The percentage values also utilise the evaluation capacity ofmodern injection moulding machines. Modern control systemssuch as NC4, enable deviations to be represented in percent-ages (see fig. 6.10). The recommended values can be directly

compared with the current Actual values. If the deviations fallwithin the tolerance limits, the component quality is acceptable.

106 107



Fig. 6.5 Fig. 6.6

108 109



Even if the quality depends essentially on the constancy of the8 previously mentioned parameters - and even if, in general,3-5 of these would suffice - it is still necessary for the lessimportant parameters to adhere to specific tolerances (fig. 6.7).

110

Fig. 6.7

111

± 1.0 % ± 2.0 % ±5.0 %

±1.0% ± 2.0 % ± 5.0 %

±1.0% ± 2.0 % ± 3.0 %±0. 1% ±0.2% ±0.3%

±1.0% ±1.5% ±2.0%

± 2.0 % ± 3.0 % ±4.0 %

± 0.1 % + 0.2 % ±0.3 %

+ 2.0 % ± 3.0 % ±4.0 %

±2.0 % ± 3.0 % ±4.0 %

±1.0% ±2.0% ±3.0%

±1.0% ±2.0% ±3.0%

± 1.0 % ±2.0 % ± 3.0 %

±3.0 % ±4.0 % ±5.0 %

±10.0% ±15.0% ±20.0%

± 2.0 % ± 4.0 % ± 6.0 %

± 2.0 % ± 3.0 % ± 4.0 %±5.0% ±8.0% ±10.0%

±1.0% ± 2.0 % ± 3.0 %

± 3.0 % ± 6.0 % ± 8.0 %

± 2.0 % ± 3.0 % ± 4.0 %

± 2.0 % ± 4.0 % 1 8.0 %

Piasticising time

Injection time

Cycle timeDosing stop

Change-over point for follow-up pressure

Residual melt cushion

Mould open - stop

Mould temperature

Flange temperature

Cylinder temperature

Melt temperature

Hot runner temperature

Hydraulic oil temperature

Room temperature

Injection pressure

Follow-up pressureBack pressure

Max. cavity pressure

Intecj-al cavity pressure

Clamping; force

M ou l d f i l l t ; i ii i 11 • • • ! 11 • i . i i i 11 ' . : : i n m ou l d

• • • • •



Quality control on the machine

When activating quality control it is important to establishwhether the process is normally distributed i.e. without influ-ences inherent in the system. Quality control is only possiblewith normal distribution. A mean value and independent upperand lower tolerance limits are then specified for the quality-determining process parameters.

Fig. 6.8 shows a screen page from the new NC4 control systemwhich was introduced with the ERGOtech machine range.

Using this page the machine setter can select from a total of25 available parameters those which are most important for aparticular moulding. The Process Statistics page can displayup to 20 parameters, and the selected parameters can then becontrolled either continuously (CPC) or statistically (SPC).

Fig. 6.8

112 113

38 38 fit 8 S • • • • • • •



Fig. 6.9 shows the maximum injection pressure in an unstableprocess and how dosing time fluctuations depend on and influ-ence the residual melt cushion. In a stable process the statisti-cal evaluation reveals only minor fluctuations for all relevantprocess parameters.

With the aid of just 2 statistics pages the machine setter caneasily monitor process constancy. "Process Statistics 1" indi-cates the ACTUAL values for the last 16 cycles. The penultimateline also shows the mean value, and theiast line the range ofmeasured values. The control system provides not only tabular

displays, but also a wide range of control features in graphform.

Fig. 6.9

At the touch of a key the system not only provides graphicevaluation, but also percentage deviation from the mean value,and the statistical distribution - (black bars to the right of thescreen) - over the last 100 cycles for each selected processparameter (injection time, dosing time, hydraulic pressure, meltcushion, cycle time ...). A thermal printer integrated in the opera-tor terminal is also available as optional equipment for printingout all screen pages. It enables the relevant quality data andproof of quality to be documented directly at the machine.

Fig. 6.10

114 115



Fig. 6.11 looks at tolerance settings for the selected processparameters, (parameters selected are indicated by a blacksquare in the column headed "permissible deviation"). In addi-tion to the upper and lower tolerances, the permissible numberof deviations per 1000 parts is also indicated. If a variableexceeds its set tolerances, by using selected parameters rejectindication can be given and this is then shown in the deviationcounter.

In such cases, providing tolerance deviation is switched on,mouldings can be automatically sorted by means of mechanical

quality flaps or a robot fitted with a reject signal. Only the mostadvanced machine control systems can offer such a compre-hensive range of possibilities for keeping processing parametersconstant over long periods of production. Such systems canindicate the effects of any emerging influences by deviationsin the process parameters and enable statistical evaluation.This represents the first step towards our aim of "Total QualityControl".

Fig. 6.11

116 117

Recognition and elimination of

surface defects in the injection

moulding process



g p

Injection moulding is an extremely complex process, in whichthe quality of the moulded parts is determined by a variety of

factors which differ from one application to the next.

Flaws in quality can be caused by machine or processing param-eters being wrongly set and by incorrect mould or moulded partdesign.

The causes of potential faults, unfortunately, are as diverse asthe injection moulding process itself. Starting with visual defectssuch as streaks, sink marks or gloss variation, through to inad-

equate mechanical properties - entrapped air, voids or unmeltedmaterial in the moulding, for example - and ending with all man-ner of dimensional deviations (see table on page 120).

This poses the question of what practical steps can be taken toeliminate the wide variety of faults.

In order to narrow down the causes, the fault must be locatedand accurately defined i.e. what it looks like, where, when andhow often it occurs. To do this you need to be familiar with themachines and process parameters listed in the tables on pages120-123 and be able to make a careful evaluation of their poten-tial influence.

This will enable you to see at what stage in the injection mould-ing process a fault can occur. The cause of surface defects,for instance, is to be found predominantly in the plasticisingand injection phase. Dimensional deviations and inadequatemechanical properties, on the other hand, occur mainly duringplasticising and injection and in the follow-up pressure phase.

The design of the mould and moulded part also has a consider-

able effect on all types of fault, with clamp force, mould opening

and demoulding playing a secondary role.

118 119



At what stage do surface defects or mechanical anddimensional defects occur on the injection moulded part?

Flaws in appearance

Charred streaks

Moisture streaks

Coloured streaksGlass fibre streaks

Sink marks

Gloss, variations in gloss

Unmelted material pellets in the moulding (non-homogeneity)

Weld line, flow lines

Jetting

Diesel effect, charring

Visible ejector imprints

Ripple effectDark spots

Matt spots near the gate

Delamination of surface layer

Cold slug, cold flow marks

Grey/black clouds

Dimensional deviations

Mouldings not completely filled

Moulding overpacked (flash formation)

Deformation on demouldingComponent warpage

Dimensional variations on the moulding

Inadequate mechanical properties

Stress cracking on the moulding, stress whitening

Entrapped air, blistering

Voids

Charred melt

Unmelted material pellets in the moulding (non-homogeneity)

Process phase

P i a s t i c i s i n g

X

XX

X

X

X

X

X

X

X

X

X

X

XX

X

X

X

X

X

I n j e c t i o n

X

XX

X

X

X

X

X

X

X

X

X

XX

X

X

X

F o l l o w - u p

p r e s s u r e

X

X

X

X

X

X

XX

X

X

X

C l a m p f o r c e

X

O p e n m o u l d

X

D e m o u i i n g

X

XX

M o u l d

X

X

X

X

X

X

X

X

X

X

X

120 121



122 123

Correct procedure for the elimination of moulding defects

Defect:

Moisture streaks

Charred streaks

Glass fibre streaks

Coloured streaks

Grey clouds

Sink marks

Voids

Blistering, entrapped air

Charring, diesei effect(surface)

Flow line, weld line

Ripple effect

Gloss, variation in gloss(polished surface)

Gloss, variation in gloss(textured surface)

Jetting

Unmelted material particles,poor pigment dispersion

Delamination

Dark spots on the moulding

Cold slug

Moulding not filled

Moulding overpacked

Moulding too small

Moulding too large

Moulding too brittle

Procedure:

Change only one parameter at atime in the suggested sequence

M e l t t e m p e r a t u r e

M o u l d t e m p e r a t u r e

G a t e c r o s s s e c t i o n

•

F o

l l o w - u p

p r e s s u r e

B a c k p r e s s u r e

I n

j e c t i o n s p e e d

S t e p p e d i n j e c t i o n s p e e d

S c r e w

s p e e d

F o l l o w - u p

p r e s s u r e t i m e

C h a n g e - o v e r p o i n t f o r

f o

l l o w - u p

p r e s s u r e

V e n t i n g

M

o i s t u r e i n m a t e r i a l

S

c r e w r

e t r a c t i o n

C

l a m p f o r c eIncrease parameter value

Decrease parameter value

Example of clamp force calculation



124 125

Example of clamp force calculation1. Establish the projected area of the moulded part

(projected moulding area x number of impressions)

2. Material: flow characteristics and melt flow index

3. Establish required cavity pressure

Wall thickness

Flow lengthFlow length/wall thickness ratio

4. The required clamp force is then calculated from:

required cavity pressure x proj. moulding area



Example of calculation for a flowerpot

Article description:

Material:

Melt flow index:

Proj. moulding area:

Flow length:

Average wall thickness:

Flow length/wall thickness:

Flowerpot

PP

MFI 35 230°C/5 [g/10 min]

162 cm2

150 mm

0.55 mm

275 : 1

126

Calculation process:

Flow length/wall thickness ratio:

Effective cavity pressure:

(see diagram on page 133)

Mould design:

150 : 0.55 = 275 : 1

600 bar

single impression

Proj. moulding area x effective cavity pressure =

162 cm2 x 600 = 972000 N = 972 kN

Result:

Clamp unit

Clamp force reserve

ERGOtech 110

approx. 13 %

127



Example of calculation for a 10 litre bucket Calculation process:Effective cavity pressure required:

(see diagram on page 133) 570 bar

Proj. moulding area x cavity pressure = clamp force

572 cm2 x 570 bar = 3260400 N

= 3260 kN

selected: ERGOtech 330

Clamp force reserve 1 %

Flow length: 380 mm

Average wall thickness: 1.10 mm

Flow length/wall thickness ratio: 340 : 1

Proj. moulding area: 572 cm2

Available cavity pressure

ref. ERGOtech 330: 577 bar

128 129



Effective pressure location dependent on position of gate andcomponent geometry

B eaker :

gate

effectivepressurelocation close to gate

Plate:

gate

effective pressure location at halfway point along flow path

The difference in viscosity in the individual materials and the

varying injection speeds cause a pressure gradient to develop

during injection. When calculating the parts, calculate the pre-

vailing pressure at the point where the effective pressure ap-

plies.

Wall thickness zones requiring use of accumulator injection andfollow-up pressure

2.72.6

2.52.42.32.22.12.01.91.81.71.61.51.4

1.31.21.11.00.90.80.70.60.50.40.30.2

0.1

Follow-up pressure higher than injection pressure

Injection and follow-up pressure the same

Check need foraccumulator

Injection pressurehigher thanfollow-up pressure

130 131

Accumulatorrequired



Product group

1 Packaging parts

2 Tech. precision partsmulti-point connectors

3 Tech. functional parts

4 Optical parts

5 High speed precision parts

6 Medical parts

7 Automotive parts

8 Tech. packaging parts

9 Office supplies

10 Gen. purpose functional parts

11 Rigid PVC parts

12 Toys

Article

Yoghurt cartonsContainersAerosol capsBuckets

Plugs, sockets,PBTP

Gear wheels,program control cylinders

LensesRear light fittings

Disposable razorsSlide framesCable ties

Disposable syringesPipettes

Radiator grillsInstrument panelsBumpers

Music cassettes

Video cassettesCD packaging

RulersSet squares

HousingsCoversVacuum cleaner housingsStorage cases

Fittings

Articles with limitedrequirements for surface

quality and dimensions

Material

PSPEPPPP

PA, PC

POM, PAPBTP

PMMA

PSPSPA

PEPP

PPABSblends

PS

ABSPS

PS, SANCAB

PPABSPPPS

PVC

PEPP

PS

Cavity pressure (bar)

600- 800500- 700400- 600500- 700

500- 700600- 800

700- 800700- 800

600- 800500- 700

400- 500400- 500800-1200

400- 500500- 600

400- 500400- 500400- 500

350- 450

300- 400400- 500

400- 500

400- 500300- 400400- 500300- 400

400- 500

250- 350

132 133

Cavity pressures required for articles from different product groups



Effective cavity pressure for component group dependent oncomponent wall thickness and flow length/wall thickness ratio

134 135

Operating instructions for

ERGOtech NC4 control system



Operating instructions for ERGOtech NC4 control systemThe performance of the ERGOtech NC4 control system is basedessentially on the use of microprocessor controls. To ensurereliability of operation all disruptive influences must be kept wellaway from the controls. By screening electrical equipment andlaying screened cable, the manufacturer has suppressed anydisturbances which might possibly be generated by the machineitself.

Attention!

Do not use suppressor adapters with LEDs (24 V test lamps) onany proportional valves between the solenoid plugs and plug-inboards. The diodes in the adapters cause the valves to mal-function. The machine operator must take appropriate steps toavoid any potential external disturbance e.g. by screening peri-pheral units (attenuators). Please refer to instructions in theoperating manual.

136 137



T h e I B E D co n t r o l p a n e l 1 LCD display2 Function group keys

3 Numeric keypad

4 Manual function keys

5 Mode selection switches (IMM)

6 Q key

7 EMERGENCY STOP

8 Integral printer

9 Floppy drive, floppy disk box10 Pump, cylinder heating, mould heating ON - OFF

11 Start button

12 Keys for robot

13 Special function keys

14 Cursor keys

15 Function group keys

16 Softkeys for menu selection

138 139



Page selection

The screen unit comprises 3 sections:

• The LCD display

• Softkeys to call up pages within a function group

• Function group keys

When a function group key is pressed, the pages relating to the

function group are listed for selection.

The individual pages within the function group can then be

called up using the softkeys.

Example:

When the function group for "Mould" is selected, the page formould parameters is called up. By pressing the relevant soft-

keys, other mould-related pages can now be selected.

LCD-display

Functiongroup keys

Functiongroupkeys

140

Overview of page selection using function group keys:

141

Softkeysfor menuselection

- 00 Main menu - Machine

- Mould - Cores- Hydr. ejector - Cores IN- Pneu. valves - Cores OUT- Speed profile

- Process optimisation - Dosing profiles- Inject ion profi le - Follow-up pressure profile- Injection unit - Data acquisition- Intrusion

- Cylinder temperature - Hot runner- Temp, control unit - Mould heating

- Program pre-select - Switch-on program- Start-up program - Purge program- Switch-off matrix - Mould catalogue- Prog, inputs - Prog, outputs

- Process statistics 1 - Process statistics 2- Process control - Statistics configuration- Product counter- SPC configuration - SPC control chart

- Quality monitoring - CAP job- CAP - next job ' - CAP shift- CAP reject - CAP statistics- Fast mould clamping system

- Handling - Robot program- Robot diagnosis

- Page layout - Set-up IBED- Gen. data 1 - Gen. data 2- Print - Password

- Service - Amendment report- Function check - Putting into operation- Control parameters - Bit control

- Alarms



Cursor keys and numeric keypad

Input keys

Cursor keys,nextline/columnto...

left

down

Input variablelarger

Input variable• smaller

Enter/ acceptancekey

Clear key

Home position

Having selected a page, the cursor can be used to select any ofthe parameters, and set values can be entered via the numerickeypad.

The specified value is then stored in the IBED memory by pres-sing the E (Enter) key. When a set value is being entered, thetop section of the screen shows the permitted minimum andmaximum for that particular field. It also shows the value pre-viously stored for that field.

To speed the setting process, the arrow keys on the numerickeypad can be used to increase or decrease the selected value.

The cursor keys have the normal repeat function i.e. cursormovement on screen is accelerated when the cursor key is helddown.

The arrow key in the centre of the cursor pad moves the cursorback to home position.

142

Mode selection switches

Operating modes can be set via the Mode Selection switches,

as follows:1 Set up

2 Manual

3 Semi-automatic

4 Automatic

5 Quality keyThe Quality key triggers a quality log after a pre-selected

number of shots.The number of shots can be specified on page

"60 Quality monitoring".

Operating mode for robot:

6 Step: stepping mode for each axis

7 Reference: all axes move to base position

8 Set stop: the robot remains in the waiting position after

the next completed command

9 I/O: robot ON/OFF

143

Up

right



Manual function keys

1 Open - close mould

2 Hydr. ejector forward - back

3 Move cores in - out

4 Open - close automatic safety guard

5 Mould height larger - smaller

6 Nozzle forward-back

7 Injection, hydr. screw retraction

8 Dosing

The manual function (symbol) keys are used for set-up and

manual operation of individual machine functions.

Manual function keys

9 Printer - hardcopy

10 Reference

11 Switch to upper/lower case with text input forHelp functions

12 Switch to alphabetic text input

13 Pneumatic valves 1-4

14 F1-F16 for special functions

The 'F' keys are reserved for special functions. The 'ABC...' keyswitches the manual and 'F' keys over to ASCII characters. The'Shift' key switches between upper and lower case.

These functions are only active on pages used for text input

(e.g. Gen. data, Mould catalogue ...)



Emergency Stop, mould heating, cylinder heating and pump ON/OFF

1 EMERGENCY STOP

2 Cylinder heating ON-OFF

3 Mould heating

4 Pump ON-OFF

5 Start button

6 Integral printer

7 Floppy drive, floppy disk box

146

When the Emergency Stop button is pressed the machine shuts

down immediately. This includes

• pump motor- Off .

• cylinder heating - Off

• mould heating - Off

Each of the following functions is switched on by pressing the

green keys:

i pump

• cylinder heating

i mould heating

When the corresponding red buttons are pressed these

functions are switched off.

Start button:

When the Start button is pressed in "semi-automatic" and

"automatic" modes, this initiates the automatic machine cycle.

In "semi-automatic" mode the machine runs for only one cycle.

The Start button must be pressed to initiate each cycle.

In "automatic" mode the machine runs continuously.

Attention!

Start-up can only occur when the following conditions have

been met:

• mould fully open

• hydr. ejector back

• cores moved out

• dosing stop reached

147

MANNESMANNDEMAG



Injection Moulding

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