CONCEPTUAL DESIGN OF TWO PLATE INJECTION MOULD TOOL FOR ... · PDF fileCONCEPTUAL DESIGN OF TWO PLATE INJECTION MOULD TOOL FOR FIVE PIN DAIMLER REGULATOR ... manufacturing of two plate

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Int. J. Mech. Eng. & Rob. Res. 2014 Kiran Tom Thomas and Ramesh Babu K, 2014

CONCEPTUAL DESIGN OF TWO PLATE INJECTIONMOULD TOOL FOR FIVE PIN DAIMLER

REGULATOR

Kiran Tom Thomas1* and Ramesh Babu K1

*Corresponding Author: Kiran Tom Thomas,[email protected]

The paper consists of designing a two plate injection mold tool for five pin regulator. The requiredcomponent study was done before the design. The components drawing are carefully scrutinizedto extract the maximum possible amount of information. Solid modeling of components is doneusing Creo-Parametric 2.0 considering all the critical dimensions. Proper material selectionand proper combination of alloys is selected for manufacturing of mould.

Keywords: Five pin regulator, Creo-parametric 2.0 software, Solid modeling

INTRODUCTIONPlastic injection moulding is one of the mostcommon methods of converting plastics fromthe raw material form to an article of use. Thisprocess is most typically used forthermoplastic materials which may besuccessively melted, reshaped and cooled.Injection moulded components are a featureof almost every functional manufactured articlein the modern world, from automotive productsthrough to food packaging. This versatileprocess allows us to produce high quality,simple or complex components on a fullyautomated basis at high speed with materialsthat have changed the face of manufacturingtechnology.

ISSN 2278 – 0149 www.ijmerr.comVol. 3, No. 4, October 2014

© 2014 IJMERR. All Rights Reserved

Int. J. Mech. Eng. & Rob. Res. 2014

1 Department of P.G. Studies, G.T&T.C, Mysore, Karnataka, India.

Injection moulding technology continuallydevelops, with major milestones including theintroduction of the first thermoplastic materials,the reciprocating screw design, engineeringmaterials, the introduction of microprocessorsfor machine control; computer aidedengineering flow simulation software, andrecently the application of expert systems foroptimized machine setup. This work presentsa vision of injection moulding for the nextmillennium to address current industry needs,and then describes some neededdevelopments to convert that vision to reality.The ultimate aim is a machine that producesno scrap material and increased productquality with reduced labour skill requirements,

Research Paper

300


low energy consumption, and minimalmaintenance. Nowadays plastic consumptionis more than metallic products due to its easeof production and high performance.Worldwide plastic consumption is at least125,000 million pounds (by weight). About36% is processed by extruders, 32% isprocessed by injection moulding, 10% by blowmoulding, 6% by calendars, 5% in coating, 3%in compression moulding, 2% in power form,and 6% using other processes thesepercentages do not correlate with the numberof machines used. Major advantages of usingplastics include formability, consolidation ofparts, and providing a low cast to performance.

OBJECTIVE OF THE PROJECTThe prime objective is to design the InjectionMould tool, produce good quality economically.

• Analyse if the part is mouldable, detect andfix problematic zones. The study of selectedmaterials has been done, to know itsphysical and mechanical propertiesassociated with moulding material andmoulding characteristics that influence tooldesign.

• Apply a shrinkage that corresponds to thepart material, geometry and mouldingconditions.

• Make conceptual design of twoplatemould.

• Populate a mould assembly with standardcomponents such as mould base, ejectorpins, sprue bush, screws, fittings and othercomponents creating correspondingclearance holes.

• Check for any fouling of ejector pin holes,cooling holes, screw holes.

• The design of injection mould tool is doneusing “creo-parametric 2.0” software.

• Before manufacturing the tool, the mouldability and quality of the component ischecked using Moldflow Analysis andcorrection if needed is implemented in thedesign.

• Creating manufacturing drawings of eachcomponent of the tool for manufacturing.

• The mould flow advisor analysis is carriedout to set injection location, confidence offill and possible type of gates for thecomponent rmance ratio.

PROBLEM FORMULATIONThe work deals with Design, flow analysis andmanufacturing of two plate injection mould toolfor five pin regulator. This is a component usedin the trucks as connectorhousing forconnecting various pins.The costumerrequirement of component for every month is1000 components. The Injection mouldingmachine available in the firm is 70 tonnagecapacities. For this optimized design wasdone.

SCOPE OF THE PROJECTThe scope of the study for this project consists:

• Study of component.

• Conceptual design and calculation.

• Core and cavity extraction.

• Analysis for the component.

• Preparation of assembly and mould basedrawings.

• Preparation of detailed drawing of core andcavity with all other mould elements.

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• Tool manufacturing, assembly andinspection.

• Try-out and rectifying the defects if found.

METHODOLOGYMethodology is a systematic approach for therealization of total task. It consists of thefollowing detail:

• Study of the component: The study of thecomponent is the most important and thefirst step for the designer. The componentdrawings are carefully scrutinized to extractthe maximum possible amount ofinformation. The important informationavailable is the critical dimensions, line ofdraw, parting line, suitable ejection system,and required side core.

• Solid model of the component: Solidmodelling of component is done using“creo-parametric 2.0” considering all thecritical dimensions.

• Step by step design Calculations: It iscarried out to determine the various designparameters that determine the final mouldclamp force required during injection,number of cavities, wall thickness of inserts,guide pillar design, design of feedingsystem, cooling calculations.

• Core and Cavity extraction: Extraction isdone by providing proper shrinkage,tolerance is provided to the dimensions towhich a cavity and core should bemanufactured in order to produce a partof desired shape and size. The usual wayto decide on the amount of shrinkage is toconsult data supplied by the materialmanufacturer. While designing shrinkageis provided depending on the type of

plastic material to be chosen for injectionmoulding. A thicker piece will have a highershrinkage value compared to thinnersection.

• Solid modelling of the tool: 3-D modellingof the entire mould is done using “creo-parametric 2.0” . The required dimensionsare determined by calculation, which is usedduring modelling of the tool.

• Mould flow analysis: Moldflow analysis iscarried before tool manufacturing todetermine input parameters to the injectionmoulding machine etc.

• Moldflow advisor analysis is carried beforetool manufacturing to select best gatelocation and confidence of fill.

• Tool try-out and troubleshooting: After thetool is manufactured and assembled, thetool is tried to see that component producedis true to the geometry and dimensionsspecified by the customer. Try-out is aprocedure where the tool is subjected toactual working condition and theperformance of the tool is noted. After thetool has been tried out, the component isthoroughly inspected for various defects. Ifany defects are found, it is suitablyreworked.

• Cost estimation: Mould cost estimation iscrucial especially for small and mediumbatch of production runs where the costof a mould represents a significantpercentage of the product developmentcost. It is the probable cost of an articlebefore the manufacturing starts. Bycompiling statement of the quantities ofthe material required and production timerequired, the probable cost is computed.

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CALCULATION OF THE 3DMODELPart DetailsName of the component: Daimler Regulator

Material: PA 66 With 33% GF(ZYTEL 70G33LBK031)

Shrinkage: 0.2-1.1%

Volume of component: 18.037 cm3

Density of material: 1.39 g/cm3

Weight of the component: 23.27 g

Number of cavities: Single cavity

Projected area of component: 101.28 cm2

(from CAD model).

V = Volume of the component, cm3 =18.037 cm3 (CAD model).

W = 1.39 x 18.037

W = 25.07 g

Total weight = W x Number of cavities

Total weight = 25.07 x 1 = 25.07 g

The weight of the sprue and the runnerrelated to the moulding must not generally beneglected. This should be considered in theformula while determining the moulding weight.The moulding weight should be substituted inthe formula and multiplied with themultiplication factor (M.F).

Total weight of single component with feedsystem = 25.07 x 1.05 = 26.325 g

Clamping TonnageClamping tonnage required = Total

Projected area of the mould × Cavitypressure x no. of cavities ...(2)

[Reference: Technical Directory on Designand Tooling for plastics, CIPET]

Injection pressure required for processingPolyamide 66 with 33% glass filled to producean engineering part is 1000 kg/cm 2

(maximum).

1/2 Of injection pressure, as cavity pressurefor easy flow materials, 1/3 of injectionpressure, as cavity pressure for viscousmaterials. polyamide 66 with 33% glass filledhas good flow-ability, hence 1/2 of the injectionpressure, may be assumed as the cavitypressure.

Tonnage required for the component =

Total projected area x 1/2 Injection

pressure x number of cavities

Figure 1: Component Details

Weight of MouldingActual weight of component, (W)

W = x V ...(1)


W = Actual weight of the component, g

= Density of plastic material, gm/cm3 =1.39 g/cm3

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= 101.28 × (1/2 × 1000) x 1

Tonnage required for the component =50640 Kg

Factor of safety of 1.3 (30% of actualtonnage) = 65,832 Kg

Minimum machine tonnage required =65.832 tonnes = 645.81 N

It is suggested that the available machineis Mathmann 70 T Machine.

Mathmann 70 T Machine is selected.

Plasticizing Capacity (ps)Plasticizing capacity of the machine iscalculated as follows,

Rated plast icizing capacity of thematerial is:

PP

PS

QQPSMaterialwithratengPlasticizi ...(3)


Plasticizing rate of polystyrene = 16.6 g/sec

qa = Total heat of polystyrene = 57 cal/g

qb = Total heat of polyamide 66 with 33%glass filled = 135 cal/g

135576.16

SP

PS = 7.00 g/s = 25.2 kg/hr

Plasticizing capacity of the machine forpolyamide 66 with 33% glass filled is 25.2kg/hr;

Machine capacity is 25.2 kg/hr; thereforemachine can be used safely. (Machine data)

Total Weight of material required per hour= 1.98 kg/hr;

Machine Plasticizing capacity for PA = 25.2kg/hr.

Machine selection is safe.

Shot Capacity (SC)The capability of machine is normallyexpressed in cubic centimeters of sweptvolume the injection cylinder. The shot is,therefore, the mass of this volume of plasticmelt at the plasticizing temperature andpressure. Thus,

Shot capacity (kg) = Swept volume xDensity of material x Cont. ...(4)

where, Constant = correction factor for percentvolume expansion of the plastic at the mouldingtemperature for PA = 0.9 (Crystallinematerials).

The screw type is normally rated in terms ofswept volume of the injection cylinder = 67.9cm3 (from Machine Specification).

Density of material = 1.39 g/cm3

Shot capacity (g) = 67.9 x 1.39 x 0.9 = 85 g

Shot capacity of the machine with PA is 85g. Since the shot weight of the component is26.325 g, the design is safe and production ofthe component can be carried out without anyrestrictions.

Determination of Number of CavitiesCalculation of Number of CavitiesBased on Shot Capacity

Ns = 0.80 × (Shot capacity/Weight ofcomponent) ...(5)


Shot Capacity of the machine for PA is 85 g

= 0.80 x (85/26.325) Ns = 2.58 = 2 cavities

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Depending on shot capacity the mould canbe designed to accommodate two cavities.But since the part is of very complex shapesingle cavity is selected.

Calculation of Number of CavitiesBased on Plasticizing Capacity

WsTsPsNp

80.0 ...(6)


Ps = Rated plasticizing of polyamide 66with 33% glass filled in grams per hour

Ts = Cycle time in seconds

Ws = Weight of the component in grams

= (0.80 x 25.2 x 48)/26.325 = Np = 36.7 =36 cavities

Depending on plasticizing capacity themould can be designed to single cavity. Hencethe design is safe.

Based on Clamping ForceBased on production rate the number ofcavities can be determined

Clamping force = 65.832 tonnes

Projected area = 101.28 cm2

Cavity pressure = 750 kg/cm2

Factor of safety = 1.05-1.2 for the injectionmoulding machine Nc = 2.47 = 2 cavities

From the above calculation it is clear that amould with single cavity is a safe design andMathmann 70 T Machine of can accommodateeasily for Single cavity, which also suitscustomer specification.

Calculation for Wall Thickness ofCore/Cavity InsertsInsert wall thickness, ,

34

EyCPd

mm ...(7)

C = Constant based on ratio of cavity lengthto depth = 0.140

P = Cavity pressure = 1000 kg/cm2

d = Depth of cavity wall = 2.5 cm

E = Modulus of elasticity = 2.1 × 106 kg/cm2

y = Permissible deflection for the insert =0.015 cm

mmcm 2.4416.0015.0101.2

5.21000140.03

6

4

Minimum wall thickness of core/cavityinserts, t = 15 mm. For safe design minimumrequired wall thickness is 15 mm. Here we get4.2 mm. Hence the design is safe.

Design of Guide PillarGuiding diameter of the guide pillar, dp

spp fN

Qd

4

...(8)

Q = Side thrust

Np = Number of guide pillars = 4 numbers

fs = Working shear stress for the guide pillarmaterial, kg/mm2

Side thrust,

Q = di x h x Pc ...(8.1)


di = Height of the core, mm

h = Maximum side of the core, mm

Pc = Pressure in the cavity, kg/cm2

Q = (2.8 x 3.5 x 1000) = 9800 Kg

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Substituting the value of the side thrustinduced, we get the minimum diameter of theguide pillar, d,

mmcmd p 15492.114004

137204

For manufacturing the guide pillar diameteris considered as 24 mm.

From the above calculation it is found that15 mm is required. For ease of manufacturingand assembly of tool we have considered24mm diameter guide pillar.

Feeding System DesignRunner DesignThe runner diameter is calculated by thefollowing formulae

7.3

4 LWD ...(9)


where,

W = Weight of the component = 23.27 g

L = Length of the runner = 30 mm

7.33027.23 4

Substituting the values in EquationDiameter of the runner.

D = 3.05 mm

Therefore diameter of the runner = 3.05 mm

Gate DesignAccording to the size and shape in this design,submarine gate is employed to feed thecomponent.

To find gate width

30Ahw

...(10)


where,

h = Constant = 0.7 for polyamide 66 with33% glass filled material.

A = Total surface area of the cavity = 10128mm2

mmW 34.230101287.0

To find Gate depth

Gate depth, hg = Avg width of gate/Avgthickness of component

where,

Avg width of gate = 1.29 mm

t = thickness of the component = 2 mm

Substituting these in the equation we have,

hg = 1.29/2 = 0.645 mm

hg = 0.645 mm is selected

Mould Cooling CalculationsHeat to be transferred from mould per hour(Q):

Q = n x m x qb ...(11)


where,

Q = Heat to be transferred per hour (cal/hr)

m =Mass of the plastic material injected intothe mould per shot (g) = 26.325 g

n = number of shots per hour (75 shots/hr)

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(Number of shots is taken from Machinedata)

qb = Heat content of plastic material, forpolyamide 66 with 33% glass filled =130 cal/g

Q = 75 x 26.325 x 130 = 256.668 KCal/hr

But in practice heat is removed by threeways

• Conduction

• Radiation

• Convection

It is found in practice, that approximately50% of the total heat input is carried away bythe water cooling systems in moulds. Thereforeamount of heat removed by cooling water is,

Qd = 0.5 x Q = 0.5 x 256.668

= 128.334 KCal/hr

Amount of Water to be Circulatedper Hour to Dissipate Geat (mw)Amount of water to be circulated to remove50% of Heat is calculated as

inoutw TTk

Qm

55.0...(12)


where,

K = Thermal conductivity of water

K = 0.65 for direct cooling

K = 0.5 for indirect cooling

Tout = Outgoing water temperature °C

Tin = Incoming water temperature °C

SW = Specific heat of water

mw = Amount of water required to remove50% of heat.

Assuming a reasonable temperaturedifference of Tout–Tin = 5 °C for water

hrkg /48.39565.0

78.269

= 0.658 lt /min

DISCUSSIONFrom the above design calculations followingdetails are assumed for manufacturing the tool:

• Total weight of single component with feedsystem is 26.325 g.

• Minimum machine tonnage required is65.832 T. It is suggested that the availablemachine is Mathmann 70 T Machine.

• Total Weight of material required per houris 1.98 kg/hr and machine plasticizingcapacity for PA is 25.2 kg/hr, hence machineselection is safe.

• Shot capacity of the machine with PA is 85g since the shot weight of the component is26.325 g, the design is safe and productionof the Component can be carried out withoutany restrictions.

• Based on shot capacity, clamping tonnageand plasticizing capacity number of cavitiesare selected as one.

• Amount of water circulated per hour todissipate heat is 0.658 litres/minute.

REFERENCES1. Glanvill A and Denton E (1965), Injection

Mould Design Fundamentals, IndustrialPress.

2. Herbert Rees (2002), MouldEngineering , 2nd Edition, HanserGardener Publications.

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3. Nagpal G R (2006), Tool Engineeringand Design, Khanna Publishers.

4. Peter Jones (2008), The Mould DesignGuide, Smithers Rapra Technology Ltd.

5. Pye R G W (2000), Injection MouldDesign, 4th Edition, Affiliated East-WestPress Pvt. Ltd.

6. Rohinton K Irani, Srinivas Kodiyalam andDavid O Kazmer (1992), “Runner SystemBalancing for Injection Molds usingApproximation Concepts and NumericalOptimization”, Advanced DesignEngineering Group, GE.

7. Whelan A (1982), Injection MouldingMaterials, Applied Science Publishers.

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CONCEPTUAL DESIGN OF TWO PLATE INJECTION MOULD TOOL FOR ... · PDF fileCONCEPTUAL DESIGN OF TWO PLATE INJECTION MOULD TOOL FOR FIVE PIN DAIMLER REGULATOR ... manufacturing of two plate