Wittmann Group

Wolfgang Roth / 2012-10

Powder Injection Moulding

P I M

Wittmann Group

Wolfgang Roth / 2012-10

Content

1.

Definition of PIM

2.

PIM - process

3.

Powder

4.

Binder

5.

Mixing

6.

Injection Moulding

7.

Debinding

8.

Sintering

9.

Part design

Wittmann Group

Wolfgang Roth / 2012-10

1.

Definition of PIM

2.

PIM - process

3.

Powder

4.

Binder

5.

Mixing

6.

Injection Moulding

7.

Debinding

8.

Sintering

9.

Part design

Content

Wittmann Group

Wolfgang Roth / 2012-10

Definition of PIM

M I M

P I M

C I M

Injection moulding
of powders

Injection moulding
of metal powders

Injection moulding
of ceramic powders

Wittmann Group

Wolfgang Roth / 2012-10

1.

Definition of PIM

2.

PIM - process

3.

Powder

4.

Binder

5.

Mixing

6.

Injection Moulding

7.

Debinding

8.

Sintering

9.

Part design

Content

Wittmann Group

Wolfgang Roth / 2012-10

PIM process

Pelletizing

Mixing

Powder

Binder

Injection Moulding

Feedstock

Green Part

Brown Part

Debinding

Finished Part

Sintering

Wittmann Group

Wolfgang Roth / 2012-10

 realisation of complex shapes

 reproducible quality and economical production of high numbers

 high quality standard

 clean production and nearly no waste

Advantages of PIM

PIM process

Wittmann Group

Wolfgang Roth / 2012-10

PIM process

Material characteristics

 high shrinkage (around 15%)

 jetting

 high thermal conductivity

 separation of powder and binder

 multi step process

 abrasive

Rules as in plastics injection moulding - but some more.

Wittmann Group

Wolfgang Roth / 2012-10

Injection
Moulding

Debinding
e.g. water-soluble systems

Sintering

Weight

Measurement

Thickness

Measurement

PIM process

Wittmann Group

Wolfgang Roth / 2012-10

1.

Definition of PIM

2.

PIM - process

3.

Powder

4.

Binder

5.

Mixing

6.

Injection Moulding

7.

Debinding

8.

Sintering

9.

Part design

Content

Wittmann Group

Wolfgang Roth / 2012-10

Typical PIM materials

Metals:

 Fe-Alloys

 steels (316L, 42 CrMo 4,...)

 hard metals (WC/Co)

 non ferrous metals (Titanium, Tungsten)


Ceramics:

 Al

2

O

3

, ZrO

2

 SiC, SiN, AlN

Wittmann Group

Wolfgang Roth / 2012-10

Types of powders for PIM

 gas atomised powders

 water atomised powders

 chemically produced powders

 mechanically produced powders

Wittmann Group

Wolfgang Roth / 2012-10

Gas and water atomised powders

Water atomisation

Gas atomisation

Wittmann Group

Wolfgang Roth / 2012-10

Chemically produced powders - e.g. hard metals,
ceramics

Tungsten powder

Wittmann Group

Wolfgang Roth / 2012-10

1.

Definition of PIM

2.

PIM - process

3.

Powder

4.

Binder

5.

Mixing

6.

Injection Moulding

7.

Debinding

8.

Sintering

9.

Part design

Content

Wittmann Group

Wolfgang Roth / 2012-10

Binder systems

 Polyolefin- / wax mixtures

 Thermoplastics

 Other: Thermoset, Agar, ...

Wittmann Group

Wolfgang Roth / 2012-10

Binder

 low viscosity of binder components

 good adhesion to the powder

 good wettability for a homogenous mixture with a low shear rate

 chemical stability

 no migration of binder components

 storage stability

 low energy requirements

Requirements for mixing

Wittmann Group

Wolfgang Roth / 2012-10

 low viscosity for complete mold filling

 good adhesion to the powder to avoid separation

 no adhesion to the tool material

 high green strength

 thermal and chemical stability while injection moulding

Binder

Requirements for mixing

Wittmann Group

Wolfgang Roth / 2012-10

Binder

 simple and complete debinding

 non-toxic and no corrosive end products

 low ash content

 low metallic residues after debinding

 decomposition temperature higher than injection moulding temperature

 selective debinding of particular binder components is possible

Requirements for debinding

Wittmann Group

Wolfgang Roth / 2012-10

1.

Definition of PIM

2.

PIM - process

3.

Powder

4.

Binder

5.

Mixing

6.

Injection Moulding

7.

Debinding

8.

Sintering

9.

Part design

Content

Wittmann Group

Wolfgang Roth / 2012-10

Mixers

Shear roll extruders

Twin screw extruders

High mixing quality is reached by
high shear mixing devices.

Wittmann Group

Wolfgang Roth / 2012-10

Content

1.

Definition of PIM

2.

PIM - process

3.

Powder

4.

Binder

5.

Mixing

6.

Injection Moulding

7.

Debinding

8.

Sintering

9.

Part design

Wittmann Group

Wolfgang Roth / 2012-10

Injection moulding process

3 Cavity
6 Heater bands
9 Hopper

2 Part
5 Nozzle
8 Screw

1 Tool (clamping side)
4 Tool (injection side)
7 Cylinder

Wittmann Group

Wolfgang Roth / 2012-10

Injection process

flow front

thermal

flow direction

frozen skin layer

melt

cavity walls

melt flow direction

Wittmann Group

Wolfgang Roth / 2012-10

Simulation of the filling phase

W-Cu

Al

2

O

3

Quelle/Source: ARCS

Injection process

Wittmann Group

Wolfgang Roth / 2012-10

Injection process

t

F

=0.01s

t

F

=0.02s

t

F

=0.06s

t

F

=0.08s

t

F

=0.15s

t

F

=0.04s

Simulation of the filling phase

Wittmann Group

Wolfgang Roth / 2012-10

Mold Filling Study with Moldflow
Plastics Insight

TM

Catamold 316LA

0,55 s 0,67 s 0,69 s 0,75 s
(filling time)

position of the

pressure transducer

in the machine die

Injection process

Simulation of the filling phase

Wittmann Group

Wolfgang Roth / 2012-10

Injection moulding machines for PIM

special PIM processes and highest precision

conventional PIM

Micro Injection Moulding

Wittmann Group

Wolfgang Roth / 2012-10

Machine characteristics for PIM

 Wear resistant screw and cylinder

 Special screw geometry depending on the feedstock system

 Automation for green parts

 Special hopper

 SPC and special quality control

 Special thermal control in the feeding zone

 Optional: Ejection with open machine door

Wittmann Group

Wolfgang Roth / 2012-10

Mould design

Design rules

Type

Draft angle

0,5° - 2°

Wall thickness

1,3

– 6,5 mm

Webbing

0,5

– 0,7 x wall thickness

Radius

0,4

– 0,8 mm

 wear resistant platens and inserts for cavity walls

 big and round shaped runner systems to avoid separation of powder
and binder

 part removal manually or by a robot system

Wittmann Group

Wolfgang Roth / 2012-10

Testing tool “wedge structure”

(Quelle/Source: IFWT, Vienna; IMM, Mainz)

Wittmann Group

Wolfgang Roth / 2012-10

Damage during ejection

(Quelle/Source: IFWT, Vienna; IMM, Mainz)

Wittmann Group

Wolfgang Roth / 2012-10

Damage during ejection

This can be avoided by an especially designed robot system

Wittmann Group

Wolfgang Roth / 2012-10

PIM Process Defects

Wittmann Group

Wolfgang Roth / 2012-10

Content

1.

Definition of PIM

2.

PIM - process

3.

Powder

4.

Binder

5.

Mixing

6.

Injection Moulding

7.

Debinding

8.

Sintering

9.

Part design

Wittmann Group

Wolfgang Roth / 2012-10

Debinding

binder

gases

part surface

powder

open pores

Wittmann Group

Wolfgang Roth / 2012-10

Debinding

Types

Typical times

 thermal

10 - 30 h

 catalytic

2 - 6 h

 by solvents

2 - 3 h

Wittmann Group

Wolfgang Roth / 2012-10

Powder size

Quelle/Source: IFWT, Vienna; IMM, Mainz

d

90

< 30



m

d

90

< 11



m

Influence of powder size on cavity filling

Wittmann Group

Wolfgang Roth / 2012-10

Content

1.

Definition of PIM

2.

PIM - process

3.

Powder

4.

Binder

5.

Mixing

6.

Injection Moulding

7.

Debinding

8.

Sintering

9.

Part design

Wittmann Group

Wolfgang Roth / 2012-10

Sintered part

Quelle/Source: IFWT, Vienna; IMM, Mainz)

Catamold 316LS, d

90

< 11



m

Wittmann Group

Wolfgang Roth / 2012-10

Material structure after sintering

Material: Steel 316L
Sintering: 2h, 1360

°C under H

2

Wittmann Group

Wolfgang Roth / 2012-10

Temperature curve for sintering

0

200

400

600

800

1000

1200

1400

1600

0

200

400

600

800

Time [min]

T

e

m

p

e

ra

tu

re

[°

C

]

Iron, Iron Nickel

Steel

Wittmann Group

Wolfgang Roth / 2012-10

Content

1.

Definition of PIM

2.

PIM - process

3.

Powder

4.

Binder

5.

Mixing

6.

Injection Moulding

7.

Debinding

8.

Sintering

9.

Part design

Wittmann Group

Wolfgang Roth / 2012-10

Tolerances

Tolerances for PIM parts

Type

Average

Max. achievable

Main dimension

0,1 mm

0,04 mm

Dimensions

0,3%

0,05%

Weight

0,4%

0,1%

Hole diameter

0,1%

0,04%

Subdivision distances

0,3%

0,1%

Angles

2°

0,1°

Flatness

0,2%

0,1%

Parallelity

0,3%

0,2%

Roundness

0,3%

0,3%

Rectangularity

0,2% / 0,3°

0,1% / 0,1°

Rouhness

0,3



m

0,01



m

Density

1%

0,2%

Wittmann Group

Wolfgang Roth / 2012-10

Separation of powder and binder

too much powder

too much binder

too much binder

Wittmann Group

Wolfgang Roth / 2012-10

Runner systems

 good: round shapes

 bad: angular shapes are causing
separation of powder and
binder

Wittmann Group

Wolfgang Roth / 2012-10

Micro precision parts

Definition for micro precision parts:

1. parts with “normal” dimensions

2. tolerances in the range of micrometers

3-



values:

shot volume:

±0,002 cm

3

sintered dimension:

±0,005 mm (±0,01%)

milling heads out of hard metal (Courtesy: Seco Tools AB)

Wittmann Group

Wolfgang Roth / 2012-10

PIM parts

Quelle/Source: Fa. Schunk Sintermetall GmbH

Wittmann Group

Wolfgang Roth / 2012-10

PIM parts

Quelle/Source: Fa. Schunk Sintermetall GmbH

Wittmann Group

Wolfgang Roth / 2012-10

Thank you for your kind attention.

Powder Injection Moulding

P I M