MIM Technology

MIM Process

  • 1 Mixing and granulation of injection materials

    Mixing and granulation of injection materials

    The metal powder is mixed with a thermoplastic polymer (usually called a binder) in a heated state, so that the surface of each metal particle is evenly covered with a layer of binder, and the resulting mixture is called feed. After the feed is cooled, it is prepared into granules with a particle size of several millimeters by a granulator, which is used as the injection molding material of the injection molding machine.

  • 2 Injection molding

    Injection molding

    The feed material is heated in the loading barrel to melt it, and the reciprocating screw is forced to feed the material into the furnace through the gate and into the mold. After cooling, the formed part is released from the mold to obtain a green stage material.

  • 3 Removal of binder (degreasing)

    Removal of binder (degreasing)

    Special degreasing equipment is used to process the green stage material after injection molding to remove 90% of the binder in the components and the remaining 10% of the residual binder plays a supporting role, so that the degreasing part can be transferred to the next sintering process. The remaining binder will be completely removed during the thermal release stage of the sintering process.

  • 4 Sintering


    Sintering is to put the degreased product on a ceramic plate and put it into a sintering furnace. Through precise temperature control, the furnace temperature is gradually increased to about 85% of the melting point of the material. The relative density of the sintered product is about 98%, and its performance is similar to that of the parts obtained after bar cutting. At the same time, sometimes in order to obtain more precise tolerances or increase material properties, the parts can be shaped, machined, heat treated and plating after sintering.

MIM Technology Advantage

  • Complex geometry

    Complex geometry

    Since MIM products are formed by a mold similar to an injection mold, a high degree of freedom in geometric design can be obtained. As long as the injection mold can form a product, it can basically be manufactured by using the MIM process.

  • Exquisite appearance

    Exquisite appearance

    Since the MIM raw material powders are all the powders with D90 below 18um, the surface roughness of the sintered body can reach about Ra0.8, which brings convenience for subsequent polishing, plating and other processing.

  • Excellent material properties

    Excellent material properties

    The high density of MIM products makes them have excellent material properties, which are basically close to the properties of sheet materials, so they are especially suitable for parts with special requirements for product function.

  • Material diversity

    Material diversity

    It has been proved that almost all materials can be produced by MIM process, but it is best to use stainless steel for production.

  • Suitable for mass production

    Suitable for mass production

    The general production lead time of MIM process is 5-7 days, and products can be supplied continuously after one production cycle. The daily output can meet the demand from several hundred to several hundreds thousand per day.

  • High dimensional accuracy

    High dimensional accuracy

    The dimensional accuracy of powder injection molding is generally around +/-0.5%, and it can be +/-0.3% in special cases.

MIM Part Design Wizard

Output Complex three-dimensional geometric shapes Expected features of MIM parts Material selection Dimensional tolerance Product function


The MIM process can achieve an annual output from as a few thousand to several million. However, because the MIM process must use molds, the MIM process is usually not used for parts with a small output due to mold costs. Generally speaking, for products with an annual output of 20,000 or more, the MIM process has more advantages, and for products with an annual output of less than 20,000, it is necessary to evaluate the investment in mold costs.

Complex three-dimensional geometric shapes

Complex three-dimensional geometric shapes

Powder injection molding is formed by filling the raw materials into a mold similar to plastic products through an injection molding machine, so it can carry out complex shape design like traditional plastic products. When the part has holes, grooves, ribs, bosses and other obvious features, the MIM process will become more useful.

Expected features of MIM parts

Expected features of MIM parts

a. Uniform wall thickness change

b. Maximum size is less than 125 mm

c. All features greater than 0.1 mm

d. Weight mass is less than 1 kg

e. Thickness is less than 10 mm

f. There is at least one plane as the sintering support surface

g. Allow the existence of parting line, gate mark and thimble mark

Material selection

Material selection

It has been proved that almost all materials can be produced by MIM process, but it is best to use stainless steel for production. This is because more than half of MIM parts are made of stainless steel, which means that it hasfundation of the largest sup base, and due to the large output, the price of the material is correspondingly lower.

Dimensional tolerance

Dimensional tolerance

The dimensional accuracy of powder injection molding is generally around +/-0.5%, and it can be +/-0.3% under special circumstances. Higher accuracy requirements mean increased costs. Therefore, it is recommended to relax some tolerances under the premise of meeting the requirements. The following table is the tolerance comparison table.

Size General MIM enterprise manufacturing tolerance Yibi manufacturing tolerance
General case Special case
1-4mm +/-0.05 +/-0.05 +/-0.03
4-10mm +/-0.10 +/-0.07 +/-0.05
10-20mm +/-0.15 +/-0.10 +/-0.08
20-30mm +/-0.25 +/-0.15 +/-0.10
feature General range Special range
Part size 0.2-50g 0.09-200g
Wall thickness 0.5mm or more 0.25 or more

Note: Special tolerance requirements can be achieved through secondary processing, such as: shaping, CNC.

Product function

Product function

Compared with traditional powder metallurgy parts, MIM parts have a higher sintered density (96-100% of the theoretical density). Therefore, the typical chemical, physical and basic thermodynamic properties of PIM materials are the same as those in the sheet material manual. Is consistent. So if performance is important, the performance of MIM products will be more competitive.

MIM technology introduction

Metal injection molding (MIM) is a net forming process, which was first used in the 1920s. The origin of some current MIMs can also be traced back to the 1960s. However, it lacked the necessary industrial foundation at that time and has not been widely used. In recent years, due to the leading role of 3C products, the MIM industry has developed rapidly and is widely used in 3C electronics, hardware accessories, power tools, lock accessories, smart wear, jewelry accessories, medical equipment and other industries. The main processes of the MIM process include: mixing, injection, debinding, sintering, and appropriate post-treatments if necessary. The MIM process has the characteristics of high cost performance, high product performance and the ability to form complex parts.

  • Compared with traditional powder metallurgy

    aMIM generally does not require subsequent processing

    bMIM parts have excellent corrosion resistance, strength and toughness

    cMIM parts have excellent magnetic properties

  • MIM compared with cutting technology

    aMIM design can save material and weight

    bMIM can shape difficult-to-cut materials into the final shape

    cMIM design can save multiple assembly operations

  • MIM compared with precision casting

    aMIM can produce smaller thickness

    bMIM roughness is better

    cThe small diameter half holes and through-holes of MIM parts have better Process-ability

    dMIM parts can greatly reduce the required finishing machining

    eMIM produces small parts at lower costs and faster delivery.

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