Metal Injection Molding
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
We still have other materials such as WC, Fe50Ni....Etc.
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 |
| 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 |