Metal powder injection molding technology

Metal powder injection molding technology

1. Micro powder injection molding technology Conventional powder injection molding technology (MIM), the powder metallurgy products that can be processed are limited to the weight range of 3 ~ 509. In recent years, due to the use of ultra-thorough processing technology, it has been possible to use small thorough molds to effectively use the MIM method to manufacture machined difficult materials and complex small and can not be post-processed or surface processed products, which is the micro-MIM method (micro-MIM). The products produced by the micro-MIM method are not the main part of MIM products at this stage, but the method can deal with difficult materials, complex shapes and parts that do not require mechanical processing, so its application range is expected to grow rapidly. From the perspective of micro-MIM technology and raw materials used in products, the size of its products is mostly below lmm, and it is difficult to adjust the quality problems such as dimensional accuracy and surface finish of products through post-processing technology, therefore, in order to meet these requirements, it is necessary to use a certain fineness of raw material powder. The powder used in the conventional MIM method has an average particle size of about 10 mm, but the micro-MIM method requires the use of a finer powder with an average particle size of about 3 mm. The surface finish of the sintered miniature MIM billet obtained by using such fine powder can reach RaO0.25m, while the conventional MIM process can only obtain RaO1.2m. Metal powder with an average particle size of about 39m can be produced by high pressure water impacting molten metal flow with high pressure of close to 1000kg/cm2, that is, high pressure water atomization method, which has been industrialized.

2. Micro metal powder injection molding method: MIM metal powder injection molding method is the use of metal powder and resin or paraffin (binder) mixture as raw materials injection molding after degreasing (the binder decomposition) and sintering to make metal products technology, is the powder metallurgy and plastic injection molding method integrated into a composite manufacturing process, it can use more fine metal powder than powder metallurgy method. Therefore, it can promote the sintering of high-density materials, greatly improve product performance, and can also manufacture small metal parts with complex shapes and higher precision. Recently, the micro-metal powder injection molding method has been further developed successfully

3.MIM method has the following five advantages:

(1) Choose finer metal powder and binder to differentiate, and the raw material has high fluidity.

(2) Homogenization of raw material billet is achieved through mixing and granulation.

(3) The use of microporous metal mold manufacturing technology to improve the material filling, molding stability, release and transportation.

(4) In the process of degreasing and sintering heating speed, can control grain growth and can prevent deformation and damage during shrinkage.

(5) A thorough evaluation technique has been established in the inspection process.

The newly developed metal powder injection molding technology of the micro-sacrificable resin mold attachment is to use the resin mold embedded in the metal mold to form a whole with the final molding body produced after the metal powder injection molding, and finally to be eliminated by degreasing and sintering. This technique prevents damage to the molding body well and is easy to handle.

4. Metal porous materials manufactured by MIM method have excellent heat resistance and mechanical properties compared with polymer porous materials, and not only good ductivity but also high electrical and thermal conductivity compared with ceramic materials, which is expected to be widely used in various filters, chemical reaction catalysts, heat exchangers, impact energy absorbers and other aspects. However, it is difficult to control the porosity, pore size and other characteristics of traditional metal porous materials manufacturing technology, as well as the final product shape correction. In order to solve this problem, Japan Taisheng Industrial Company has recently developed a PSH method (Powder-space-holder), which is used as a raw material for metal Powder injection molding (MIM) composed of metal powder and binder, adding a third component material to form a pore to form a resin powder, and producing porous metal materials through molding, degreasement and sintering processes. This method can control the pore size and porosity as well as the structure of porous bodies by changing the particle size and amount of added resin powder, and can prepare porous metal materials with very small pore size and connected pores.