Metal Injection Molding

Application of Metal Injection Molding MIM in the Field of Petroleum Exploitation

Development of MIM Parts

Metal powder injection molding (MIM) is a new powder metallurgy technology that began to be researched in the 1970s and developed rapidly in the 1980s. Since MIM technology can form high-precision complex shapes or special-shaped blanks at one time, it is difficult to process hard alloys and other materials. The molding of materials is of great significance. Qinhuangdao Zhongwei Precision Machinery Co., Ltd. is specialized in the development and production of injection molding products of iron-based, stainless steel, cemented carbide, high-density tungsten alloy, aluminum alloy, copper-based and other metal powder metallurgy materials. And sales, cemented carbide metal injection molding, powder metallurgy tools, industrial accessories, auto parts, daily accessories, tool accessories, fishing accessories, electronic accessories, watch accessories, fishing gear accessories and other accessories in various industries, mass production of precision, Companies with complex three-dimensional shapes and metal components with special performance requirements.

●Development history of MIM parts

In the 1970s, the powder injection molding (PIM) process of ceramic spark plugs began to appear;

1979----Parmareh metal injection molding products won two awards, and the MIM process attracted the attention of the industry;

1986—Japan Nippon Seison introduced MIM technology, and my country began experimental research on MIM technology;

1990 ---- Israel's Metalor company introduced MIM technology and established MIM production line;

1997~2000----my country's May 3rd Research Institute, Beijing Iron and Steel Institute and Central South University successively established MIM company MIM technology gradually industrialized in my country;

2000~2006——my country's MIM enterprises continued to innovate, and the domestic MIM industry showed an annual growth trend;

From 2006 to present - Benefiting from the innovation of BASF's feeding technology and the wide application of MIM technology in the consumer electronics field, the MIM industry has entered a period of rapid growth since 2012.

●MIM part process flow

●Advantages of MIM parts

Unrestricted structure: complex metal parts can be directly formed like plastic injection molding, allowing free design of three-dimensional shapes. In theory, all shapes that can be formed by plastic can be realized by MIM process;

Reliable physical properties: the product has a uniform structure and good density, the density can reach more than 98% of the theoretical density, and the product strength, hardness, elongation and other mechanical properties are high;

High product accuracy: the dimensional accuracy of the product can reach +/-0.3% in one forming, and the products with general accuracy requirements do not need post-processing;

Significant batch cost advantage: The near-net-shape process, compared with other processes, especially for products with complex structures, has a significant cost advantage in mass production using the MIM process.

●MIM part disadvantages

Qinhuangdao Zhongwei Precision Machinery Co., Ltd. has two technologies of PM powder metallurgy and MIM injection molding. The head office has developed in the powder metallurgy industry for 60 years, and has a very deep understanding of both powder metallurgy and MIM injection molding technology. Next, analyze the shortcomings of MIM injection molding.

There are advantages and disadvantages. MIM injection molding will have special advantages in certain aspects, such as production efficiency, production costs, or parts of geometric patterns produced, etc., but the disadvantage is that the parts produced are limited in volume, or Cracking, holes, short shots, jetting, poor mold opening, flash, bubbles, formation of weld lines and surface concave, bending and poor control of dimensional accuracy, etc. These problems can be eliminated by adjusting the interrelationship of time, temperature and pressure during the injection process.

The most important part of injection molding is the powder mixing process in the initial stage. If there is a problem in the mixing process, it is difficult to make up for the shortcomings caused by the mixing in the later stage. For example, when agglomeration occurs in the feed, it will cause the filling to be unstable, and the MIM powder metallurgy product will have obvious problems during the injection process.

If there is agglomeration of the avoided feed, the next thing to pay attention to is the strength and density of the formed blank. The pressure gradient that occurs during the hardening of the formed blank causes a slight density gradient, which is the cause of sintering distortion. The density gradient at the gate is large, especially when the densification process is not designed properly, and the tendency for defects in the formed blank is greater when the solid powder content exceeds a critical value.

Powder metallurgy manufacturers usually have their own mold making departments. When making molds, there is usually an air outlet to prevent air from staying in the forming blank. The quality of the surface polishing of the mold affects the burr and flash of the blank. In injection molding, flash can stick the mold. Another most common problem is short shots, which are caused by the solidification of the mixed powder before injection molding.

The problem of uneven surface in the depression is also a defect of injection molding. The reason is that during the injection molding process, the feeding material is insufficient to fill the mold cavity. When the feeding material is insufficient, the mold cavity does not have sufficient powder mixing. Shrinkage occurs during cooling. This problem can be solved by reducing the temperature, increasing the injection speed and modifying the pressure distribution of the density.

Injection molding injection speed is conducive to filling the cavity, but in practice the injection speed is difficult to achieve, because the feed is relatively viscous and dense. Flow resistance along the flow path can be reduced by removing the nozzle valve and increasing the size of the sprue, runner and gate. A better option is to inject along the powder line, which avoids changing the flow direction at the junction. Once the flow direction changes, the resistance will be

increase, and the problem of binder and powder separation.

The flow direction of some injection molding powders has changed, and some of them have not changed, so the direction of movement is not uniform, resulting in different densities of powder metallurgy blanks formed by feeding materials in the mold cavity. Here are just a few of the problems that occur in MIM injection molding. Of course, a good powder injection molding blank can only be completed by strictly controlling each link. The control of the injection molding machine now provides the functions of pressure, shear rate, temperature, measurement and action required for forming. In the future, cemented carbide injection molding will be applied in various fields of life. At present, we are familiar with oil extraction, Injection molding has been popularized in the automotive field, medical field, communication field, etc.