It belongs to injection molding knowledge points and parts in various industries

Metal injection molding

Time: June 8, 2021

Venue: Meeting Room of Lianyungang Fuchi Intelligent Manufacturing Technology Co., Ltd

Speaker: Liang Junhui

Participants: Lianyungang Dongmu New Materials Co., Ltd. Business Department

Content: training on knowledge points of MIM injection molding

Purpose: master relevant knowledge of the MIM industry

This morning, Lianyungang Fuchi Intelligent Manufacturing Technology Co., Ltd. held a training on the basic knowledge of MIM injection molding. All business department personnel participated in this meeting to enhance their working ability and better serve customers.

Main methods of this training

1. Have a preliminary understanding of the advantages and disadvantages of MIM technology

Through this morning's training, we learned that the advantage of MIM injection molding process is that it can manufacture complex parts, but the disadvantage is that * * * is controlled within 200g, and the powder fineness is about 4-8 microns. The reason is that the metal powder raw materials used by MIM are about 10 times that of conventional powder metallurgy. The higher the cost of raw materials used, the lower the advantages of MIM.

The number of parts produced by MIM powder injection molding process is * * *. Because the shrinkage rate is very large, the reason is that each blank formed by MIM injection molding contains a large amount of adhesives. These adhesives tightly wrap the injection powder to achieve the normal popularity of raw materials in the mold, so as to keep the density stable. However, these adhesives will fade in the process of degreasing and sintering, so the shrinkage rate of the product is relatively large. If the produced parts want to keep constant * * *, they are produced in a one-time mass production. At this time, many people are worried about rust, but this is not true. If the stainless steel raw materials used in MIM injection molding are placed in a dry and normal environment, there will be no problem for two years. Secondly, the MIM mold can inject 2, 4, 8 and 16 pieces at a time. Therefore, small batch products are not suitable for MIM process. The sintering time of MIM injection molding is different from that of conventional powder metallurgy. The sintering time of conventional powder metallurgy parts is expected to be four hours, while the sintering time of MIM injection molding blank parts is expected to be twelve hours. The furnace temperature needs to be controlled, and the binder in the blank is slowly removed to achieve a more stable state of the blank.

In the production of high-density powder metallurgy parts, MIM injection molding has an advantage. The density can reach 7.6-7.8g, while the conventional powder metallurgy pressing is about 6.8. The density of production is different when raw materials with different productivity are selected. For example, if MIM is made of stainless steel, the density will be controlled to about 7.6. Superalloy shall be selected and the density shall be controlled at about 7.6. Kewa alloy is selected, and the density is controlled at 7.8. High specific gravity gold is used, and the density is controlled at 18.3. Because it contains tungsten composition, etc., there are several low density parts. Titanium alloy is selected, and the density of the injection molded parts produced is about 4.2. Usually, this will be used in aerospace technology, because the material density is low, and the body weight is reduced. It will also be seen in the mobile phone industry, because weight will affect the feeling of using a mobile phone. In the face of the rapid development of mobile phone industry, it may take only a few months for a project to come out of technology, so the MIM industry needs to understand the pulse of the industry and keep up with the pace of the times.

2. The following lists the MIM metal injection molding parts used in medical, automotive, electronic IT, aerospace, consumer goods, firearms and other industries

MIM produces orthodontic parts in the medical field. The product is very small. It was seen in the mouth of some orthodontic friends before menstruation. This part is made of 316L stainless steel.

Surgical instruments. Previously, surgery needed to be performed on the body. Now, surgery can be performed by making a hole in the body and using MIM metal injection molding surgical forceps. This technology is relatively new. Only around 2015 did MIM technology complete the surgical forceps in the final shape of * * *. The stainless steel used has a density of about 7.65, an ultimate tensile strength of 900 MPa, a yield strength of 730 MPa, and a hardness of 25 HRC.

The application of MIM in the automobile industry, such as thousands of temperatures in the engine, can be used in such an environment for injection molded parts made of Kova alloy materials. For example, the engine rocker arm, which is made of low alloy steel, controls the variable valve timing stroke of the engine. MIM is especially complex in structure and light in weight.

The blade on the turbocharger, which is used in the automobile diesel engine turbocharger, is completed by the successful MIM injection process. This part can meet strict dimensional tolerance requirements, and the blade profile can reach a precision of plus or minus 0.015mm by cutting. This blade is produced by a professional mold. This mold has an excellent slider function and can reduce deformation when it is released. MIM production can reduce the production cost by 20%.

The proportion of MIM parts used in electronic communication instruments is * * *, accounting for about 50% of all MIM industries. Plug sockets with complex shapes are basically MIM products and some electronic products. Small and complex parts with low production cost and high performance requirements are basically produced by MIM technology.

For example, the outer cover of optical fiber transceiver, which looks very complex, is also made of stainless steel MIM metal injection molding technology.

Mobile phone parts card inserter. One mobile phone can hold three mobile phone cards or two cards. The card holder is a MIM part. Now there are more aluminum and plastic parts used, which can reduce the weight of the mobile phone. Even if it is one gram, there are so many parts in the mobile phone, which together have obvious effects. To measure whether the universal device has market competitiveness, the feel of its use is very important.

The camera of the mobile phone, the filter screen of the mobile phone speaker, the slider and the hinge cylinder of the mobile phone are all completed by MIM injection molding technology.

MIM technology uses different materials, such as Kova alloy, which can effectively improve the high temperature resistance and reduce the weight of parts. This advantage is particularly suitable for the aerospace industry. For example, the seat belt parts produced with the advantage of high strength are also controlled at 100g. After heat treatment, the tensile strength of this complex part is 200MPA.

In the past, the compression seat of the oil outlet valve was completed by stamping and cutting, and its weight is not as strong as that of MIM manufacturing. Now it has been replaced by MIM powder injection molding. This saves a lot of production costs. Parts used in aerospace and medical are expensive. More importantly, unified production of MIM facilitates assembly and improves the performance of parts.

Rocket burner, which is a thruster device, is a niobium alloy part. Its shape presents geometric figures, and too complex structure can only be selected by * * * through MIM technology.

MIM is also often seen in daily necessities, such as parts in watches, parts in small motors, parts on eyes, photographic machinery, etc.

At the early stage of the development of MIM technology, as only a few competent enterprises owned and mastered these technologies, and later, they gradually became popular. MIM products have both small size, complex shape, high strength, medium or high surface roughness and medium or precise tolerance. Because the process is aimed at the final shape of the product, the injection molding blanks produced have basically been formed, saving expensive machining costs. When the number of required parts reaches a certain standard, the MIM process is competitive.

To fully understand the benefits of MIM metal injection molding, you must know the advantages and disadvantages of MIM Wang Yi:

MIM process can make production highly automated, so it is competitive for mass production

MIM parts can be designed into very thin walls, and can also have fine boring holes, threads and other details

Compared with cast metals and alloys, the price of raw materials for MIM process is higher. This is the main reason why MIM parts are usually quite small

Because the material cost of small parts only accounts for a small part of the total production cost

The MIM process is environmentally friendly. At the same time, it consumes less energy than other production processes. The more expensive the raw materials are, the greater the advantages will be.