MIM

INTRODUCTION of MIM PROCESS

Metal injection molding (MIM) is a technology that combines the strengths of conventional powder metallurgy and plastic injection molding. It is the most cost-effective process in making small parts with complicated shapes.

The process starts with kneading fine metal powders and thermoplastic binders. The kneaded feedstock is then granulated and fed into injection molding machine. Under pressure and heat, the feedstock flows into the mold cavity forming the desired shapes. After being removed from the mold, the molded parts go through a debinding process to remove the binders. The debound parts are then sintered to a density greater than 95%

process :
Metal powder → Kneading → Injection Molding → Debinding and Sintering (machining) → Finished part

Process information about MIM
tooling detail no. of cavities 1~8
tooling life time per cavity 200000 shots
cleaning interval after every production
molding process temp. 80~185
hydraulic injection pressure 500~1500 bar
process name of injection molding machine ARBURG ; FANUC
name of sintering oven Shimadzu
process time injection 30 second
debinding 12Hr ~ 24Hr
sintering  18Hr ~ 24Hr
other process (total in days) 7~14
total capacity of injection per day (pcs) 1500~8000
delivery time of optimal batch in days 30~45

Injection Molding equipment
Injection Molding Equipment
Debinding and Sintering Equipment (Japanese Equipment – Shmadzu)
Debinding and Sintering Equipment (USA Equipment – CVI)
Size of the parts before and after sintering.
Photo of the MIM samples

Typical material composition and properties
Properties density (g/cm3) Tensile Strength ( MPa ) Elongation ( % ) Hardness Before Heat Treated Hardness After Heat Treated C% Ni% Mo% Cr% Cu% Others Fe
Fe-2% Ni 7.5 350 20 HRB 85 Max.HRC52 < 0.15 2 - - - - Bal
Fe-8% Ni 7.6 450 25 - - < 0.15 8 - - - - Bal
4650 * 7.5 1500 2 HRC 18~30 Max.HRC55 0.5 2 0.5 - - - Bal
316L 7.4 500 40 HRB 70 - < 0.03 11 2.2 17 - 1.4Mn Bal
440C 7.5 1600 2 - Max.HRC55 1 0.6 0.75 17 - 1.0 Mn / 1.0 Si Bal
17-4PH * 7.5 1200 4 HRC22~33 Max. HRC 38 0.05 4 - 17 4 - Bal
M2 * > 8.0 1800 0.5 - Max. HRC 62 0.9 - 0.5 4 - 2.0V / 6.0W Bal
We still have other materials such as WC, Fe50Ni....Etc.

Product name metal injection molding part / MIM
production process Forming (injection) / debinding / sintering / tumbling / machining
features When part is too complex and small to be produced by conventional powder metallurgy process, then MIM is a good choice. 
material fine sintered metal powder with plastic binder : Fe2Ni, Fe8Ni, 4605, 8640, stainless steel 316, stainless steel 17-4, M2, Tungsten carbide / WC and many other materials
applications electrical parts, locking system part, industrial machine parts, automobile component, aircraft component, medical appliance component