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
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
Definition of PIM
Injection moulding
P I M
of powders
M I M C I M
Injection moulding
Injection moulding
of ceramic powders
of metal powders
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
PIM process
Powder
Mixing Pelletizing
Feedstock
Binder
Injection Moulding
Green Part Debinding Brown Part Sintering
Finished Part
Wittmann Group Wolfgang Roth / 2012-10
PIM process
Advantages of PIM
żð realisation of complex shapes
żð reproducible quality and economical production of high numbers
żð high quality standard
żð clean production and nearly no waste
Wittmann Group Wolfgang Roth / 2012-10
PIM process
Material characteristics
żð high shrinkage (around 15%)
żð jetting
żð high thermal conductivity
żð separation of powder and binder
żð multi step process
żð abrasive
Rules as in plastics injection moulding - but some more.
Wittmann Group Wolfgang Roth / 2012-10
PIM process
Injection
Moulding
Thickness
Measurement
Sintering
Weight
Debinding
Measurement
e.g. water-soluble systems
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
Typical PIM materials
Metals:
żð Fe-Alloys
żð steels (316L, 42 CrMo 4,...)
żð hard metals (WC/Co)
żð non ferrous metals (Titanium, Tungsten)
Ceramics:
żð Al2O3, ZrO2
żð SiC, SiN, AlN
Wittmann Group Wolfgang Roth / 2012-10
Types of powders for PIM
żð gas atomised powders
żð water atomised powders
żð chemically produced powders
żð 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
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
Binder systems
żð Polyolefin- / wax mixtures
żð Thermoplastics
żð Other: Thermoset, Agar, ...
Wittmann Group Wolfgang Roth / 2012-10
Binder
Requirements for mixing
żð low viscosity of binder components
żð good adhesion to the powder
żð good wettability for a homogenous mixture with a low shear rate
żð chemical stability
żð no migration of binder components
żð storage stability
żð low energy requirements
Wittmann Group Wolfgang Roth / 2012-10
Binder
Requirements for mixing
żð low viscosity for complete mold filling
żð good adhesion to the powder to avoid separation
żð no adhesion to the tool material
żð high green strength
żð thermal and chemical stability while injection moulding
Wittmann Group Wolfgang Roth / 2012-10
Binder
Requirements for debinding
żð simple and complete debinding
żð non-toxic and no corrosive end products
żð low ash content
żð low metallic residues after debinding
żð decomposition temperature higher than injection moulding temperature
żð selective debinding of particular binder components is possible
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
Mixers
Twin screw extruders Shear roll 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
1 Tool (clamping side) 2 Part 3 Cavity
4 Tool (injection side) 5 Nozzle 6 Heater bands
7 Cylinder 8 Screw 9 Hopper
Wittmann Group Wolfgang Roth / 2012-10
Injection process
flow front
melt flow direction
cavity walls
thermal
flow direction
frozen skin layer
melt
Wittmann Group Wolfgang Roth / 2012-10
Injection process
Simulation of the filling phase
W-Cu Al2O3
Quelle/Source: ARCS
Wittmann Group Wolfgang Roth / 2012-10
Injection process
Simulation of the filling phase
tF=0.02s
tF=0.04s
tF=0.01s
tF=0.06s
tF=0.08s
tF=0.15s
Wittmann Group Wolfgang Roth / 2012-10
Injection process
Simulation of the filling phase
position of the
pressure transducer
in the machine die
Catamold 316LA
Mold Filling Study with Moldflow
0,55 s 0,67 s 0,69 s 0,75 s
Plastics InsightTM
(filling time)
Wittmann Group Wolfgang Roth / 2012-10
Injection moulding machines for PIM
conventional PIM
special PIM processes and highest precision
Micro Injection Moulding
Wittmann Group Wolfgang Roth / 2012-10
Machine characteristics for PIM
żð Wear resistant screw and cylinder
żð Special screw geometry depending on the feedstock system
żð Automation for green parts
żð Special hopper
żð SPC and special quality control
żð Special thermal control in the feeding zone
żð Optional: Ejection with open machine door
Wittmann Group Wolfgang Roth / 2012-10
Mould design
żð wear resistant platens and inserts for cavity walls
żð big and round shaped runner systems to avoid separation of powder
and binder
żð part removal manually or by a robot system
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
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
gases binder
powder
part surface
open pores
Wittmann Group Wolfgang Roth / 2012-10
Debinding
Types Typical times
żð thermal 10 - 30 h
żð catalytic 2 - 6 h
żð by solvents 2 - 3 h
Wittmann Group Wolfgang Roth / 2012-10
Powder size
Influence of powder size on cavity filling
d90 < 30 mðm d90 < 11 mðm
Quelle/Source: IFWT, Vienna; IMM, Mainz
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
Catamold 316LS, d90 < 11 mðm
Quelle/Source: IFWT, Vienna; IMM, Mainz)
Wittmann Group Wolfgang Roth / 2012-10
Material structure after sintering
Material: Steel 316L
Sintering: 2h, 1360°C under H2
Wittmann Group Wolfgang Roth / 2012-10
Temperature curve for sintering
1600
1400
1200
1000
800
600
400
200
0
0 200 400 600 800
Time [min]
Iron, Iron Nickel Steel
Wittmann Group Wolfgang Roth / 2012-10
Temperature [°C]
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 mðm 0,01 mðm
Density 1% 0,2%
Wittmann Group Wolfgang Roth / 2012-10
Separation of powder and binder
too much binder
too much powder
too much binder
Wittmann Group Wolfgang Roth / 2012-10
Runner systems
żð good: round shapes żð 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-sð values:
shot volume: Ä…0,002 cm3
sintered dimension: Ä…0,005 mm (Ä…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
Powder Injection Moulding
P I M
Thank you for your kind attention.
Wittmann Group Wolfgang Roth / 2012-10