[Technology] New metal injection molding technology: μ- Introduction to MIM and 2C-MIM process

[Technology] New metal injection molding technology: μ- Introduction to MIM and 2C-MIM process

In fact, it is not too new technology. It has been used in production^_^

In recent years, with the aim of manufacturing metals and alloys that can be used for mass production of micro-parts and micro-structure surfaces, the micro-metal injection molding process has been developed（ μ- MIM）。 μ- MIM has greatly improved the availability of metals and alloys for micro applications, such as new materials with high temperature stability, strength and toughness, as well as thermal conductivity and magnetism.

In addition, compared with micro injection molding of plastics, μ- The bimetal production process developed by MIM enables two different metal materials to be connected together (bimetal co-injection) during the injection molding process.

The small editor extracted some content from the industry works and briefly introduced the current situation of these two processes.

1. Bimetal co-injection 2C-MIM (Two-Component MIM)

[Technology] New metal injection molding technology: μ- Introduction to MIM and 2C-MIM process

Porous surface and dense inner core titanium implants

As a method of manufacturing bimetallic parts, 2C-MIM (Two-Component MIM) process has been developed. The main advantage of 2C-MIM process is that in one production process, two materials with different properties can be directly combined together, thus reducing subsequent connection operations (such as welding, riveting, fastening assembly, etc.).

The range of parts that 2C-MIM can manufacture includes hollow parts with complex internal structures to flexible detachable components.

The purpose of all studies is to manufacture engineering parts with enhanced functionality at a favorable cost. For parts that are easy to wear, hard or wear-resistant materials can only be used for local reinforcement at key parts such as friction surfaces, and other structural parts can be made of relatively low-cost materials.

To manufacture bimetallic parts, it is not enough to simply understand the injection molding shape of the two injection materials. The key is that the two materials must be able to be sintered in the same furnace and under the same sintering atmosphere. Because the shrinkage of the two parts is different during sintering, it may cause delamination or cracking. Also, when harmful phases are formed, alloying elements will also diffuse along the boundary, which will reduce the performance of the material.

[Technology] New metal injection molding technology: μ- Introduction to MIM and 2C-MIM process

17-4PH/316L composite tensile sample prepared by co-injection

By coordinating processing factors, the quality of 2C-MIM parts can be optimized. Because of its unique ability, a part can have different material properties without any assembly operation. Therefore, the 2C-MIM process will certainly expand the application market of the MIM industry.

2. Micro metal injection molding process（ μ- MIM）

[Technology] New metal injection molding technology: μ- Introduction to MIM and 2C-MIM process

Microinjection stainless steel reaction vessel

Products and systems are tending to miniaturization, which means that the structure and functional parts in complex systems will become smaller and smaller.

This requires not only the use of advanced materials with appropriate physical properties, but also the microminiaturization of geometric features, so as to increase the number of integrated functions.

Therefore, it is necessary to develop highly effective and reliable methods for manufacturing micro-parts or micro-structure parts μ- Micro structure parts manufactured by MIM can be used to replace plastic parts to obtain the advantages of mechanical properties, corrosion resistance or high temperature performance of metal materials.

The success of this new manufacturing process is based on the fact that its competitive process is limited by processable materials or large production capacity, and there is no cocoa substitute μ- MIM。

LIGA technology (combination of photolithography and electroforming) is generally only applicable to 2D geometry, and is limited by electroforming in material selection.

Other technologies, such as electrochemical micro-manufacturing methods, micro-milling and micro-grinding technologies, all come from the silicon-based microelectronics industry, and they all have the ability to solve problems as small as 1 μ The ability of m features, however, is not suitable for mass production of 3D parts.

Now, use μ- The feature size of micro parts produced by MIM can be as small as 5 μ m。 However, in order to optimize the performance, for example, according to the flow characteristics or the shape of the part, people have developed a completely possible μ- Submicron or nanometer special injection materials required by MIM.

Generally speaking, for micro-parts, MIM can replicate features about 10 times the average particle size, which is particularly applicable for micro-parts. If you want to manufacture smaller features, you need to apply finer powder. Now, available metal powder 1 μ m。 Some powders are too active to produce powders of this size range (for example, Ti), while other metal powders are easier to produce by special atomization (for example, stainless steel).

If the particle size range of the powder is less than 1um, special injection materials should be used to adapt to the problems caused by the large surface area injection molding and degreasing of the powder.

[Technology] New metal injection molding technology: μ- Introduction to MIM and 2C-MIM process

Microinjection stainless steel gear and impeller

Now? μ- MIM is still in the cultivation stage, and is generally developing in parallel with 2C-MIM process. First of all, both of these processes have been used in production, but both are in the process of technology introduction and feasibility study on various micro parts or micro structure parts.

On the way to successfully enter the market, preliminary competitive research and development objectives are key work, but only by focusing on 2C in the industry- μ- The possibility of MIM to develop materials and production processes, coupled with the education of engineering and technical personnel, can achieve a real breakthrough.