SLS Total Quality Management (TQM) for Rapid Manufacturing

Mitglied der Fachhochschule Ostschweiz FHO 1www.fhsg.ch © FHS St.Gallen

SLS Total Quality Management (TQM) for Rapid Manufacturing

Gideon N. Levy1, Ralf Schindel, Peter Schleiss, Adriaan SpieringsFHS University of Applied Sciences St. Gallen, SwitzerlandInstitute for Rapid Product Development (1Head of Institute)

Frankfurt, November 2006


FHS

St. G

alle

n

Mitglied der Fachhochschule Ostschweiz

FHO

© 2001 by FHS St. Gallen

Welcome!

Inst

itute

RPD


Institute RPD at the EMPA SG

InstituteRPD

Architect: Theo Hotz, ZurichInauguration: 15th August 1996

Award-winning: European Prize for industrial buildings

Constructer-Prize 1996

Inst

itute

RPD


Inst

itute

RPD


Inst

itute

RPD


Inst

itute

RPD


SLM

Inst

itute

RPD


Agenda

• Introduction

• What is Rapid Manufacturing (RM)?• The Rapid Manufacturing Process• TQM Matrix Overview• Some Specific Requirements• SLS in line quality Examples

– Q1 Materials– Q2 Layering– Q3 Components– Q4 Post processing

• Conclusions


What is Rapid Manufacturing (RM)?

• Rudgley M. defines RM as “the manufacture of end-use products using additive manufacturing techniques (solid imaging)”

• RM must guarantee long-term consistent component use for the entire product life cycle or for a defined minimal period for wearing parts. This calls for a most significant role of materials in the LM technologies as argued later.

• RM must guarantee TOTAL QUALITY components

Def

initi

on a

nd C

lass

ifica

tion


RM – of: Wash Blocks

Rap

id M

anuf

actu

ring


RM – of: Transport elements

Rap

id M

anuf

actu

ring


RM – of: Transport elements Logistics

05

10

152025

303540

[Stück]

07.10.05 21.10.05 04.11.05 18.11.05 02.12.05 16.12.05

[Zeit]

Bestell - EingangGeometrie 4Geometrie 3Geometrie 2Geometrie 1

Rap

id M

anuf

actu

ring


The Rapid Manufacturing Process

TQM

Mod

el

Plastics

Metals

Ceramics

Composites

Solid Liquid Gases

Powder

Foil

Wire

Material

Thermal Layering

Chemical Layering

postprocessing

traditionalprocessing

coatingfinish

Q1

Q2 Q3

Q4 Q5 Q6Q3

Part

DATA


Rapid Manufacturing TQM Matrix Overview

Means Description Pre-requirements Process

dependency existing new

Q1

Mat

eria

ls • Input quality of process

specific material grades • Behavior over time • Shelf time

• Database • Characterization • Virgin material • standards

strongly process and material grade dependent

Q2

Laye

ring

• Process equipment state Energy source

• Material ageing • Recycling

• Calibration • Preventive

maintains • Repeatability

Strongly materials , parameters and system stability

Existing standards

• Materials norms

• Durability over time,

• Porosity measure

Dimensional quality Geometry and allowances

RE techniques

Q3

Com

pone

nt

• mechanical • physical • chemical, • electrical properties

Product spec Destructive add-on parts

Existing standards

Q4

Post

trea

tmen

t

• Removal residual loose materials

• Infiltration, • Post curing • Heat treatments

TQM

Mod

el


Some Specific Requirements

• Use simple quick straight forward verification methods• Based on scientific and experimental specific data• As generic as possible • Based on known standards and procedures• Avoid component specific intensive investment needs

in labor and equipment• Minimal preparation work in programming and

procedures• Usable for as many as possible Layering process• Propose new Rapid Manufacturing Standards if

necessary

TQM

Mod

el


Q1

Mat

eria

l


Virgin Material Specifications deviations consistencyAverage 6 Batches Mean STABW Variant

Ø σ 6σ

Particle size <100 µ 95 - 100 % 99.22 0.35584266 2.15% 0.15828< 63 µ 60 - 85 % 71.79 2.61514359 21.86% 8.54872< 10 µ 0 - 5 % 3.35 0.56856310 101.71% 0.40408

D50 40 - 60 µ 52.79 1.46059714 16.60% 2.66668 influence?

Fluidizing factor (SAMES) > 100 132 8.19679816 37.33% 90 better!

Melting point of polyamide DSC 183 - 189 °C 185.5 0.32015621 1.04% 0.14

Crystallization point DSC 145 - 155 °C 147.4 0.29154759 1.19% 0.11

Mold Flow Index (@235c) MFI virgin > 100 @ 235 °C ? ? ? ? missing

☺• Delivered virgin material in

specifications • Virgin material in close

allowances • Good repeatability

• Spec. not always available to end user• MFI a significant value missing• Fluidization?• Are other values needed?

Q1

Mat

eria

l


Fluidization humidity control others?

Influence range?

Q1

Mat

eria

l


Virgin powder MFI measure @ 235 °c

0.00

20.00

40.00

60.00

80.00

100.00

120.00

30.07

.2004

30.10

.2004

30.01

.2005

30.04

.2005

30.07

.2005

30.10

.2005

30.01

.2006

30.04

.2006

190 C 235 C Linear (235 C) Linear (190 C)

• Virgin PA powder has different thermal and viscosity properties then recycled powder

• Virgin PA powder has shorter polymer chains and lower viscosity

• Virgin low viscosity PA powder is more economic in the recycling

• MFI measurement standards?

Q1

Mat

eria

l


Material aging (shelf time?) DSC measurement

Q1

Mat

eria

l


Q2

Laye

ring


ATC Advanced Temperature Control

Q2

Laye

ring

-Sys

tem


TEMPERATURE STABILIZATION UPGRADE

STABLETEMP™ TEMPERATURE STABILIZATION UPGRADE

Integra Services now offers the StableTemp™Temperature Stabilization Upgrade for your 2000, 2500 CI, 2500 Plus, and Vanguard Laser Sintering Platforms.

StableTemp™ will eliminate the need to ramp your part bed temperatures during a build no matter the build height. Just set your temperatures, run the build and StableTemp™ will take care of the rest, build after build. Q2

Laye

ring

-Sys

tem


Q2

Laye

ring

-Sys

tem


Q2

Laye

ring

-Sys

tem


Sytem controls: The Pro Sinterstation

Scanning galvomotors working in closed position loop

CO2 laser beam energy measured and kept constant

The themo IR sensor is on line calibrated closed loop control


Boeing Patent EP 1 486 317 A1 (Pri. 10.6.2003)

Q2

Laye

ring

-Sys

tem


Powder Management

• The powder is changing propertied over use• The melting point is raising• The viscosity is growing

• For good results and constant quality we have to take care and worked under constant conditions in a well define allowence field

• For PA 12 the sieving, mixing virgin, humidity control and other (?) parameters are essential.

• The most significant parameters have to be measurable and adjustable or controllable.

• A strict documented powder management is required• No standards or agreed methods available• No reporting


Regeneration mixing principle and system

X ?

Q2

Laye

ring

-Rec

yclin

g


Powder Materials (MFI) Measurement

Q2

Laye

ring

-Rec

yclin

g


Examples: Q2 Layering (MFI) material prior

-10.0

0.0

10.0

20.0

30.040.0

50.0

60.0

70.0

80.0

90.0

1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 65

Build (run)

MFI

QAMFILinear (MFI)

Virgin

Recycled

Inferior quality

Q2

Laye

ring

-Rec

yclin

g


Poor MFI of PA powder (orange peel)

• Use: virgin PA powder or recycled only• Use: constant MFI material for each batch• Gain: constant viscosity and melting point• Obtain: better builds, better accuracy better repeatability

Q2

Laye

ring

-Rec

yclin

g


Q3

Com

pone

nts


Examples: Q3 Components (dimensions)

Measurements conventionally or with RE methods, especially for freeform parts with larger allowances. Q3

Part

s –

Dim

ensi

ons


Examples: Q3 Surface Topology : how standards?

Q3

Part

s –

Dim

ensi

ons


Q3 Components - Properties

Product connector set Inbuilt destructive ring specimen Testing machine

Inbuilt special designed mechanical testing procedure specimen and testing equipment,

(SLS Duraform ) Source: Griesbach, VG. Kunststofftechnik

Component placeholder, build especially in a measurable geometry and is undergoing a destructive test Q

3 Pa

rts

–Pr

oper

ties


RPD Periodik Consistency test

T bone Groups (5 connected)

5 pillars points X position

5 plane orientations

4 sidewall

Total: [5x5x5] + [4x5] = 145 T bones to measure! (x parameter set) !!! Q3

Part

s –

Prop

ertie

s


Density ( Archimedes) stainless steel 1.4404

( )tmm

mw

wa

as ρρ ⋅

−= Q

3 SL

M D

ensi

ty


Density ( Archimedes) stainless steel 1.4404

( )tmm

mw

wa

as ρρ ⋅

−=

Density material DIN 1.4404 13.11.2006

Temperature 23.5 c

(23,5) water 0.9974 Concept laser M1

Laser scann speed [mm/sec] Weight in air [g] Weight in distilled water [g]

Density [g /mm3]

Density deviation to

mean250 16.412 14.344 7.913671037 2.394%300 16.304 14.238 7.872820324 1.865%350 16.128 14.069 7.813701462 1.100%400 15.790 13.743 7.695175413 -0.433%450 15.684 13.624 7.591634155 -1.773%500 15.200 13.175 7.485005658 -3.153%

mean 7.728668008

standard deviation 0.142181007

Density DIN 1.4404 [g /mm3]

7.47.57.67.77.87.9

8

0 100 200 300 400 500 600

V [mm/sec]

Den

city

[g/c

m3]

Q3

SLM

Den

sity


Comparison standard material CL20 -RPD material – development for stainless steel

* After SLM process

Mechanical properties of 1.4404- Tensile strength > 650 – 700 MPa- Yield point RP0.2 > 530 MPa

⇒ Significant higher values compared to Concept CL20

Yield point stainless steel - SLMSlice Thickness 30 um

0

100

200

300

400

500

600

700

0 degree 45 degree 90 degree

R p0.

2 [M

Pa]

CL20

1.4404M

Tensile Strength stainless steel - SLMSlice Thickness 30 um

0100200300400500600700800900

0 degree 45 degree 90 degreeR m

[MPa

]

CL20

1.4404M

Representative calibration and qualification of system, material in accordance with usual standards actually confirm periodically supplier or own material data

Q3

SLM

Den

sity


Comparison standard material CL20 -RPD material – development for stainless steel

* After SLM process

Very high density- > 99% for standard processing parameters- Typical ≈ 99.5%

1.4404 (RPD) 1.4404 (Concept CL20)

Q3

SLM

Den

sity


Q4

Post

pro

cess

ing


Q4 Post processing – Infiltration I

0

200

400

600

800

1000

1200

0:00

1:16

2:33

3:49

5:06

6:22

7:39

8:56

10:12

11:29

12:45

14:02

15:18

16:35

17:51

19:08

20:24

Time [h, min]

Tem

pera

tur

[ ° C ] ,

Tdi < 450 0CDe-binding

Mechanicalsupporting

Thermal Sintering

SetBottomTop

Q4

Post

pro

cess

ing


Q4 Post processing – Infiltration IIINFILTRATION PROTOCOL Parts Build 719_LF_XITZ

Date 20.06.2006Sinterstation DTM 2500 ++

Oven cycle 213_LF 100oven heat ramp (°/h) 120

temperature (°C) 1080hold time (h) 3N2 flow (l/h) 40

Part Part 1 Part 2 Part 3 Part 5green part weight (g)

green part + tabs weight (g) 75 75bronze % 0.72 0.72factor 1.72 1.72calculated bronze weight (g) 54 54actual bronze weight (g) 54.5 54.5% difference (.< 1%) 0.93% 0.93% #DIV/0! #DIV/0!length bronze bar (mm) 9.1 9.1 0.0 0.0

Actual infiltrated parts weight (g)infiltrated part weight (g)

infiltrated part + tabs weight (g) 128.35 128.35infiltrated part weight (%) #DIV/0! #DIV/0! #DIV/0! #DIV/0!

infiltrated part + tabs (> 99%) 99.50% 99.50% #DIV/0! #DIV/0!

Q4

Post

pro

cess

ing


Conclusions

The introduction of a TQM methodology and model in the Rapid Manufacturing branch is vital. The amount of dedicated scientific and applied work is still very limited. The problem is complex multidimensional and often material and RP process dependent. Nevertheless the conventional methods standards and instrumentation deliver a good applicable base.•The appeal and confidence in Rapid Manufacturing can and must be increased dramatically by applying TQM.•The topic has to be on the RM community agenda. An extensive agreed TQM methodology supported by international standards is a must.Otherwise the RM will remain a higher volume Rapid Prototyping affair

Con

clus

ions


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SLS Total Quality Management (TQM) for Rapid Manufacturing