Three Misunderstandings of MIM (metal injection molding)

Three Misunderstandings of MIM metal injection molding:

1. Odor problem in the process of feedstock mixing

Direct cause: POM decomposes due to friction and heat during the mixing process, producing pungent formaldehyde gas.

Cause 1: The shape of the powder is not good, resulting in increased friction, increased heat and decomposition.

Cause 2: The particle diameter of the powder is too small, the relative surface area increases, and the friction area increases and decomposes.

Cause 3: The mixing temperature is too high, leading to decomposition.

Responses:

1. Choose powder with higher tap density.

2. Choose coarser powder without affecting other properties.

3. Adjust the proper mixing temperature.

4. Add POM stabilizer to prevent decomposition during mixing.

2. The polishing performance of MIM stainless steel products

Myth: The higher the sintering temperature, the better the polishing performance

Since MIM sintering belongs to powder sintering, it is inevitable that there will be closed pores inside to form an internal residual pore area, and a dense area can be formed on the surface, and a rough surface area will be formed on the outside due to factors such as volatile matter precipitation.

Myth: The higher the sintering temperature, the better the polishing performance

The purpose of polishing: to polish the rough area of the surface layer, expose the dense area, and prevent the internal residual hole area from being touched.

The higher the sintering temperature, the more serious the volatilization and precipitation of elements may be, the thicker the surface rough layer is, and the depth of polishing needs to be increased.

Under the premise of ensuring the same sintering density, the lower the sintering temperature, the easier it is to polish.

Sintered density is key. The higher the sintering density, the less residual pores inside and the better the polishing performance.

The key factors of polishing performance: 1. Sintering density; 2. Polishing process.

3. The problem of bluing on the surface of MIM stainless steel products

Description of the problem: After the product burns out, it turns blue under a stereoscopic microscope.

Misunderstanding: The powder raw material is impure.

Responses:

1. Clean the atmosphere in the furnace and adopt partial pressure sintering.

2. Choose powder with coarse particle size.

3. Adjust the sintering temperature.