What are the criteria for selecting MIM process? When is the MIM process suitable?

What are the criteria for selecting MIM process? When is the MIM process suitable?

The process technology, materials and equipment of MIM process have become more and more mature in China, and the application range is also very wide.

The complex shape, small size and large output of parts are the advantages of MIM process.

These strengths have made it widely used in electronic and digital products, light weapons, watches, hand tools, dental braces, automotive engine parts, electronic seals, cutting tools and sports equipment.

The following figure lists some examples of MIM products..

What are the criteria for selecting MIM process? When is the MIM process suitable?

Parts with thick and thin sections

What are the criteria for selecting MIM process? When is the MIM process suitable?

Forming heel cutting in MIM sintered cemented carbide nozzle

What are the criteria for selecting MIM process? When is the MIM process suitable?

Use hollow to reduce mass and wall thickness

What are the criteria for selecting MIM process? When is the MIM process suitable?

Reinforcing rib inside the cover

What are the criteria for selecting MIM process? When is the MIM process suitable?

Use simple web stiffening to link two parts

 

So, how to determine whether a product should choose the MIM process, that is, what are the criteria for selecting the MIM process?

What are the criteria for selecting MIM process? When is the MIM process suitable?

Examples of MIM parts that show geometric characteristics that are beneficial to production

At present, the following main issues need to be considered before selecting the MIM process.

1. Quality and cutting quantity: MIM has great advantages in reducing production costs for parts with very high material loss and time-consuming processing in cutting and grinding;

2. Total demand: mold costs and R&D costs are hard to bear for products with low demand after sharing. Therefore, when the annual demand of products reaches or exceeds 20000 pieces, MIM process can be considered.

3. Material: MIM process is a near-net forming technology. MIM is the most attractive for parts designed from materials that are difficult to cut, such as titanium, stainless steel and nickel alloy.

4. Product complexity: MIM process is most suitable for manufacturing multi-axis parts and multi-reference parts with complex geometric shapes and requiring many times of changing processing stations during cutting.

5. Use performance: based on the high density of MIM products, if the use performance is required, the performance formed by the high density of MIM is competitive.

6. Surface roughness: The surface roughness reflects the size of the initial powder particles.

7. Tolerance (accuracy requirement): The tolerance of MIM sintered parts is about ± 0.3%. If the tolerance required by the product is very strict, the MIM sintered parts need secondary processing, such as CNC, CNC lathe, etc. The cost of MIM also tends to increase, and needs to be evaluated and compared.

8. Combination: In order to save inventory and assembly costs, multiple parts can be consolidated into one part.

9. Defect: The inherent defect of MIM must be placed in a non-critical position or can be removed after manufacturing, such as gate mark, ejector pin mark or binding line.

10. New composite materials: MIM can produce new composite materials that are difficult to be manufactured by traditional processes, such as laminated or two material structures or wear-resistant and consumable mixed metal-ceramic materials.

There are many kinds of materials commonly used in MIM, but several are the main ones. If the material is difficult to be machined, such as tool steel, titanium, nickel alloy or stainless steel, it is the most advantageous for the final forming of MIM. MIM process can form complex geometric features at one time.

The performance that can be achieved with MIM is different between different production sites. Before we design, many performance parameters we need are summarized in the technical manual.

Now, we have seen many new materials designed for MIM, including laminated structure (hard magnetic soft magnetic, magnetic nonmagnetic, conductive insulating), foam metal and hole construction. These optional projects have pushed MIM into fields where there is almost no technology to replace.