Answers to Basic MIM Process Questions

 

Date：[2023/10/27]
 

What is MIM technology?
The full name of MIM is metal injection molding, which means metal injection molding. A manufacturing technology that combines plastic injection molding technology with traditional powder metallurgy.
How does MIM work?
Fine metal powder is bonded with thermoplastic and adhesive to form a raw material, which is actually plastic particles containing metal powder and adhesive. Then, through the injection molding method that everyone is very familiar with, the desired product embryo is formed. Then, processing is carried out to remove the adhesive component (called degreasing), and the degreased product is finally heated and sintered in a controlled high-temperature environment to obtain dense metal parts.
Did the metal melt during the forming process?
No, only when the adhesive melts can the powder flow like plastic material. Cooling adhesive is a component that has a certain strength. The components are then degreased and sintered to remove the binder, achieving high density and strength to meet their mechanical performance requirements.
What is the difference between MIM and conventional PM processes?
Traditional PM uses unidirectional high pressure to press rough metal powder into a fixed position to manufacture moderately complex equipment. Especially, the density was not further improved during the sintering process. The density value generated by this method ranges from 80% to 90%, which limits its physical properties as an alloy. Due to the elasticity of MIM, manufacturing complex products is not limited. The combination of fine metal powder and high-temperature sintering enables the final product produced by MIM to achieve high density. This makes MIM products and precision materials have similar characteristics.
Will the components shrink during the removal of the adhesive?
No, the volume of the components will not change during the degreasing process. However, up to 20% deformation will occur at the zero part during sintering.
What will be the density and strength of the MIM section?
The density of a typical MIM is theoretically higher than 96%. The specific density characteristics depend on the choice of alloy, but in any case it is close to precision materials.
Why use MIM?
MIM has advantages in manufacturing precision and high complexity components, which are difficult or cannot be produced using traditional machining or casting techniques due to cost issues. For specific reference, please refer to the article: Guidelines for selecting MIM processes.
8. What materials can be used for production?
Almost all metal alloys can be used in MIM processes,. Among the commonly used materials in MIM, typical alloys include high-strength steel, nickel plated stainless steel, and superalloys. Other material processing includes refractory alloys, titanium and copper alloys, and low melting point alloys such as brass, bronze, and zinc aluminum, but it is not economical to use in MIM processes.
What is the best way to achieve MIM benefits?
In the early design stage of the product production cycle, applying MIM technology is the best way to achieve MIM benefits.
10. Delivery cycle?
The typical processing and sample submission lead time is 8-10 weeks. However, according to specific engineering requirements, the corresponding delivery cycle can be shortened.
11. What is the average annual output?
Generally speaking, the average annual production of a typical product should exceed 20K.
Is there a criterion for defining complexity?
There is no right or wrong here. According to the thumb rule, if a drawing has dimensions exceeding 20, it is suitable to become a good MIM component.
13. Are there any restrictions?
Like any other technology, MIM technology also has limitations, with a maximum weight limit of 240 grams (from an economic perspective, the weight is generally limited to no more than 50 grams). Some geometric characteristics may also have problems (ultra thick or ultra thin sections). In recent years, the progress of technology has continuously exceeded the maximum weight of MIM products.
14. What tolerances will be achieved?
The typical MIM tolerance is 0.3% to 0.5%. However, the tolerance largely depends on the geometric characteristics of the product. Exceeding the tolerance of MIM technology can be achieved through machining.
15. What equipment is used in the process?
The MIM process mainly uses the following equipment: MIM mixing and granulation equipment, MIM injection molding equipment, MIM degreasing equipment, MIM sintering equipment, and MIM post processing equipment.
Can MIM be thermally or electroplated?
Yes, MIM components, like traditional machined products, can undergo heat treatment, electroplating, mechanical processing, forging, PVD vacuum plating, and more.