MIM(Metal Injection Molding)
MIM(Metal Injection Molding) is a forming method by injecting the plasticizing mixture of metal powder and binder. It can be consist of 4 steps: 1, Mix the powder and binder, and then pelletize the mixture; 2, Injection molding; 3, Remove the binder to get the 100% metal parts; 4, The last is sintering. Some sintering products may need to do further densification processing, heat treatment and machining. Sintered products not only have the same complex shape and high precision as plastic injection forming, but also have similar physical, chemical and mechanical properties as forged parts.
This technology is suitable for mass production of metal parts with small shape , precise and complex 3D shape, and has special performance requirements.
MIM Production process:
Mold design⇒ mixing powder(metal powder and binder) ⇒ injection molding⇒ sintering ⇒ further machining
(according to requirements) ⇒ inspection ⇒ packaging
History of MIM :
The earliest traceable history of MIM is the early of 1920’s, beginning with the production of powder injection molding of ceramic spark plugs, the next few decades powder injection molding focused on ceramic powder injection. Until 1979, the metal injection molding products of the company Parmatech that built by Wiech and other people won two awards. And when Wiech and Rivers has been patented successively. After hat, metal injection molding become the leading technology of powder injection molding.
In the past, MIM’s development and application is relatively slow. The reasons are the lack of powder and high price of material, imperfect knowledge platform, immaturity of the technology, people understand and market accept time is not long, production (including mold manufacturing) cycle is too long, investment is not enough, etc.
To solve the difficulty of MIM technology and fulfill its practical utility, the United States made a high powder engineering program in the mid 80’s, which research contents include 18 topics related to the injection molding. Then Japan, Germany etc. Began the research on the development of MIM positively. Wiech formed the company Witec in 1980, Brunswick entered MIM industry in 1982 and acquired Witec, and then gradually registered the Omark industry, Remington military, Rocky dental etc. In 1986, the Japanese Nippon Seison introduced Wiech process. Israeli company Metalor2000 introduced Wiech technology from Parmatech, and built the MIM production line.
With the deepening of the MIM research and development of new types of binder, pulverizing technology and the advance of degreasing process, MIM has achieved industrialization at the early of 1990’s. After nearly 30 years of efforts, MIM has become the developing rapidly, the most promising near net shaping technology in the filed of international powder metallurgy. And has been hailed as on of “the most popular metal parts forming technology”.
Application of MIM:
Metal powder injection molding has been widely used in mechanical industry, electronic industry, automobile industry, office automatic industry,
● Computers and auxiliary facilities: printer parts, core, striker shaft pin, drive parts
● Tools: such as gun drill, drill chuck, power tools, hand tools, wrenches and other spare parts, milling heads, nozzles, etc.
● Household appliances: such as watch case, bracelet, electric toothbrushes, scissors, fans, golf head, simulation jewelry, tool heads and other parts;
● Medical equipment parts: dental orthopedic frame, orthopedic bracing parts, scissors, tweezers;
● Military ordnance parts: the missile tail, firearms parts, warheads, liner, Fuze parts;
● Electrical parts: such as micro-motor parts, electronic parts, sensors, cell phones etc.
● Mechanical Parts: complex parts such as small loose cotton, textile machines, sewing machines, office machinery, and other machinery parts;
● Automotive, marine parts: clutch inner ring, radial inserts, fork sets, distributor cover, car airbags, car locks;
● Oil drilling with various special-shaped carbide nozzles.
Materials that suitable for MIM technology:
Iron base alloy steel, stainless steel, nickel base alloy, tungsten alloy, hard alloy, titanium alloy, magnetic
materials, fine ceramic etc.
Commonly used materials and their application fields:
Table1
The performance of several typical materials:
Table2
Characteristics of MIM technology
MIM technology combines the advantages of powder metallurgy and plastic injection molding , breaks the limits on the shape of the product of traditional metal powder press molding , and absorbs the advantages of plastic injection molding in large quantities and high efficiency of shaping parts with complex shapes. It has become a near_net shaping technology of manufacturing high quality precision parts with unmatched advantages compared to conventional powder metallurgy, machining and precision casting.
● Produce complex shape of small metal parts just like producing plastic pats, normal weight between 0.1~200g ;● Molding complex parts like the production of plastic products, such as external grooving, external thread, tapered outer surface, cross through holes, blind holes, key pin, stiffener plate, knurled surface and so on.
● Good surface finish, high dimensional accuracy, the usual tolerance of ± 0.3% ~ 0.5%;
● Wide range for materials, products with high density (up to 95% to 99%), and homogeneous, high performance;
● Stable product quality, high production efficiency, can be automated, high-volume, large-scale production.
Forming ability comparison of MIM and precision casting:
Table3
Comprehensive comparison of MIM and other processes:
Table4
Production cost comparison between MIM and other processes
Chart 1
Production capacity comparison of MIM and other processes
Chart 2
+86-0769-85397751
English
German
Spanish
French
Italian
Portuguese
Japanese
Korean
Arabic
Russian
Chinese