MIM combines the advantages of powder metallurgy and plastic injection molding, breaks through the limitations of traditional metal powder molding process in product shape, and uses plastic injection molding technology for mass production and efficient forming of complex-shaped parts. It has become a near-net forming technology for modern manufacturing of high-quality precision parts, with incomparable advantages over conventional powder metallurgy, machining and precision casting.
Compared with other metal forming processes such as sheet metal stamping, MIM can form parts with highly complex geometric shapes.
Generally speaking, MIM can also complete the complex part structure that can be completed by plastic injection molding.
Applying this feature, MIM has the opportunity to merge multiple parts originally processed by other metal molding into one part, simplify product design, reduce the number of parts, and thus reduce the assembly cost of the product.
High material utilization rate MIM molding is a near-net forming process, and its parts and their shapes are close to the final product form, with a high material utilization rate, which is particularly important for the processing loss of precious metals.
Uniform microstructure, high density and good performance of partsMIM is a fluid forming process. The presence of adhesive ensures the uniform arrangement of powder, thereby eliminating the uneven microstructure of the blank, and then the density of the sintered product can reach the theoretical density of its material.
Generally speaking, MIM can reach 95%~99% of the theoretical density. High density can increase the strength, toughness, ductility, electrical conductivity and thermal conductivity of MIM parts, and improve magnetic properties.
The density of parts pressed by traditional powder molding can only reach 85% of the theoretical density at most. This is mainly due to the friction between the mold wall and the powder and between the powders, which makes the pressing pressure unevenly distributed, resulting in uneven microstructure of the pressed blank. This will cause the pressed powder metallurgy parts to shrink unevenly during the sintering process, so the sintering temperature has to be reduced to reduce this effect, resulting in large porosity, poor material density, and low density of the product, which seriously affects the mechanical properties of the parts.
High efficiency, easy to achieve mass and large-scale production. MIM uses injection molding machines to mold green products, which greatly improves consumption efficiency and is suitable for mass production. At the same time, the consistency and repeatability of injection molded products are good, which provides a guarantee for mass and large-scale industrial production.
Wide range of applicable materials and broad application fields. Metal materials suitable for MIM are very common. In principle, any powder material that can be cast at high temperature can be made into parts by MIM process, including difficult-to-process materials and high-melting point materials in traditional manufacturing processes. Metal materials that can be processed by MIM include low alloy steel, stainless steel, tool steel, nickel-based alloy, tungsten alloy, cemented carbide, titanium alloy, magnetic material, Kovar alloy, precision ceramics, etc.
In addition, MIM can also conduct material formula research according to user requirements, manufacture alloy materials of arbitrary combination, and mold composite materials into parts. MIM molding of non-ferrous alloy aluminum and copper is technically feasible, but it is usually processed by other more economical methods, such as die casting or machining.
