The indispensable key technology of 4D printing -- metal powder injection molding technology

The indispensable key technology of 4D printing -- metal powder injection molding technology

Core tip: The so-called 4D printing technology is a kind of material that can automatically deform. Put this self deformable material into water, and it will automatically fold into corresponding parts according to the product design

The so-called 4D printing technology is a kind of material that can automatically deform. Put this self deformable material into water, and it will automatically fold into the corresponding shape according to the design of the product. Isn't it novel and magical! In fact, the truth is very simple. The main line of the popular 4D printing concept in the market is "memory alloy". Memory alloy is a kind of martensitic transformation alloy with regular atomic arrangement and volume less than 0.5%. This alloy will deform under the action of external force. When the external force is removed, the original shape can be restored under certain temperature conditions. It is called "memory alloy" because it has the function of recovering more than one million times. Of course, it can not be like human brain thinking memory, more accurately, it should be called "alloy of memory shape". In addition, memory alloys have the advantages of non magnetism, wear resistance, corrosion resistance and non-toxic, so they are widely used. Scientists have now discovered dozens of alloys with different memory functions, such as titanium nickel alloy, gold cadmium alloy, copper zinc alloy, etc.

It needs to be pointed out that there is an indispensable key technology in the production process of a number of "memory alloys", including titanium nickel alloys, that is, powder metallurgy technology!

In reality, as a new technology in the field of powder metallurgy, metal injection molding (MIM) has become a suitable process to produce titanium alloy parts with complex shapes.

The data show that metal and ceramic powder injection molding (MIM) is a new manufacturing technology of metal and ceramic parts. It is a new manufacturing technology, which was invented by Parmatech Company in California in 1973. In the early 1980s, many European countries and Japan also put great effort into studying this technology and it was rapidly promoted. Especially in the mid-1980s, this technology has achieved rapid development since its industrialization, increasing at an alarming rate every year. So far, more than one hundred companies in more than ten countries and regions, such as the United States, Western Europe and Japan, have been engaged in the product development, development and sales of this technology.

It is a new part processing technology by introducing polymer injection molding technology into the field of powder metallurgy. This technology applies the principle of injection molding in the plastic industry to mix metal, ceramic powder and polymer binder into a uniform viscoplastic fluid, which is injected into the mold by an injection machine, then removed the binder, and then sintered into full densification to produce various parts.

In recent decades, metal injection molding (MIM), as a new powder metallurgy technology, has developed rapidly. The material systems that can be applied include: Fe Ni alloy, stainless steel, tool steel, heavy alloy, hard alloy, titanium alloy, nickel base superalloy, intermetallic compound, aluminum oxide, zirconia, etc. That is to say, metal injection molding (MIM), a new technology in the field of powder metallurgy, is an indispensable key technology for preparing the key 4D printing material - "memory alloy"!

According to the relevant research statistics, the materials for metal powder injection molding have developed from the early iron base, cemented carbide, ceramics and other systems that are insensitive to impurity content and have not very strict performance requirements to nickel base superalloys, titanium alloys and niobium materials. The application of materials has also developed from structural materials to functional materials, such as heat sink materials, magnetic materials and shape memory alloys. The material structure has also developed from a single homogeneous structure to a composite structure. Metalworking injection molding technology can realize the simultaneous forming of powders with different compositions, so sandwich composite structures can be obtained. For example, the combination of 316L stainless steel and 17-4PH alloy can realize continuous adjustment of mechanical properties. An important development direction of powder injection molding is closely related to micro system technology. It is closely related to microsystem technology. In the fields related to microsystems, such as electronic information, microchemistry, medical devices, etc., devices are increasingly miniaturized and functions are more complex. The powder injection molding technology provides the possibility of realization. Micro injection molding technology is an improvement on traditional injection molding technology. It is a forming technology developed for parts whose size and structure are as small as 1um. The basic process is consistent with traditional injection molding, but the particle size of raw material powder is smaller. A microfluidic device with a surface microstructure accuracy of 10um and a stainless steel part with a size of 350um~900um have been developed using micro injection molding technology; The co sintering or co connection of different material compositions and composite structures is realized, and magnetic/nonmagnetic, conductor/non-conductive micro composite parts are obtained.

Recently, in terms of the speculation of the 4D printing concept, the market started from "memory alloy" to "photosensitive resin", and in the future, it is bound to carry out in-depth exploration of "powder metallurgy technology"!

Keywords: MIM metal injection molding MIM processing metal injection molding parts powder injection molding metal injection molding metal injection molding metal injection molding metal powder injection molding

                                                                                                               ---------------Qinhuangdao Zhongwei Precision Machinery Co., Ltd