Metal Powder Injection Molding Technology

Metal Powder Injection Molding (MIM) is a new type of powder metallurgy near net composition technology that incorporates modern plastic eruption forming skills into the powder metallurgy category. The basic skills of the process are: Firstly, the solid powder is uniformly kneaded with an organic binder, and after granulation, the thermoplastic resin is injected into the mold cavity in a state of heating (~150 DEG C.) to be solidified in a mold cavity, and then chemically used. The method of thermal differentiation removes the binder in the formed billet, and finally obtains a final product through sintering and densification.

Metal Powder injection molding (MIM) is a new type of powder metallurgical near-net-forming technology that incorporates modern plastic eruption forming skills into the powder metallurgy category. The basic skills of the process are: Firstly, the solid powder is uniformly kneaded with an organic binder, and after granulation, the thermoplastic resin is injected into the mold cavity in a state of heating (~150 DEG C.) to be solidified in a mold cavity, and then chemically used. The method of thermal differentiation removes the binder in the formed billet, and finally obtains a final product through sintering and densification. Comparing with traditional skills, it has high precision, uniform arrangement, excellent function, lower production cost, and its products are widely used in electronic information engineering, biomedical equipment, work equipment, cars, machinery, hardware, sports equipment, watches and clocks, Weapons and aerospace industries. Therefore, internationally, it is generally believed that the development of this skill will lead to an innovation in the forming and processing skills of parts, and is known as the "more sought after component forming skills" and "21st century forming skills".

Parmatech, California, USA was founded in 1973. In the early 1980s, many countries in Europe and Japan also devoted great energy to the beginning of the study of this skill, and they were agilely implemented. Especially in the middle of the 1980s, this technology has made rapid progress since the end of industrialization, and it has been increasing at an alarming rate every year. So far, more than a dozen companies in more than a dozen countries and regions such as the United States, Western Europe, and Japan have engaged in commodity development, R&D and sales of this skill and skill. Japan is very lively in the competition and has performed outstandingly. Many large-scale companies have participated in the implementation of MIM industry. These companies include Pacific Metals, Mitsubishi Steel, Kawasaki Steel, Kobe Steel, Sumitomo Mine, Seiko - Epson, and Tatung. Special steel and so on. At present, there are more than forty companies specializing in MIM industry in Japan. The total value of MIM industrial products has already surpassed that of Europe and has been catching up with the United States. So far, there are more than 100 companies in the world engaged in commodity development, R&D and sales of this skill, and MIM skills have thus become more active in the frontier skills of new manufacturing operations and pioneering skills of the international metallurgical profession. Master direction MIM skills representing powder metallurgy skills

The metal powder blasting molding skill is a multi-discipline transparent and interspersed product such as plastic forming skills, polymer chemistry, powder metallurgy skills, and metal data science. The mold can be used to blow molded preforms and produce high density and high speed after sintering. Accuracy and three-dimensionally disordered structural parts can quickly and accurately transform design thinking into finished products with certain structural and functional characteristics, and can directly produce batches of output parts. This is a new innovation in the production of skills. This skill not only has the advantages of less powder processing, less cutting or less cutting, and superior economic benefits, but also overcomes the disadvantages of traditional powder metallurgy techniques such as finished products, non-uniform materials, low mechanical functions, and difficulty in forming thin walls and messy structures. Particularly suitable for mass production of small, messy and special needs of metal parts. Skills Process Binder → Mixing → Eruption Molding → Degreasing → Sintering → Post-processing

Powder metal powder

The particle size of the metal powder used in the MIM technique is usually 0.5 to 20 μm. In theory, the finer the particles, the larger the specific surface area and the easier to form and sinter. The traditional powder metallurgy skills use coarser powders larger than 40 μm. Organic adhesive

The role of the organic adhesive is to bond the metal powder particles so that the mixture is heated in the eruption barrel to have rheology and lubricity, that is, the carrier of the powder movement. Thus, the choice of adhesive is the carrier of all powders. Therefore, sticking and picking is the key to all powder spray molding. Demand for organic adhesives:

1. Use less, use less adhesive to make the mixture have better rheology;

2. No reaction, there is no chemical reaction with the metal powder in the process of removing the adhesive;

3. Easy to remove, no carbon residue in the finished product. Mixing

The metal powder and the organic binder are evenly blended together, so that various materials become blends for hair spray molding. The degree of homogeneity of the mixture directly affects its activity, and thus affects the eruption molding skill parameters, resulting in the final data density and other functions. Eruption forming The process of this step is in common with the process of plastic eruption molding. The equipment conditions are also the same. During the eruption molding process, the mixture is heated to a rheological plastic material in the eruption barrel, and is written into the mold under the appropriate eruption pressure to form a blank. The eruption molded blanks should be uniformly and microscopically uniform, and then the finished product should be uniformly shortened during the sintering process. extraction

Before molding, it is necessary to remove the organic binder contained in the blank during sintering. This process is called extraction. The extraction skill is necessary to ensure that the adhesive is gradually discharged from the different parts of the blank along the microchannels between the particles without reducing the strength of the blank. The rate of removal of the binder generally follows the dispersion equation. Sintering can shorten the porous degreased body to densification and become a finished product with certain arrangement and function. Although the function of finished products is related to many skill factors before sintering, in many cases, the sintering skills have a large, even decisive impact on the metallurgical arrangements and functions of finished products. Post-processing For parts with finer scale requirements, make necessary post-processing. This process is the same as the conventional heat treatment process for finished metal products. The MIM technique's characteristic MIM skill is compared with other processing skills. The particle size of the material powder used in MIM is 2-15 μm, while the powder size of the original powder metallurgy powder is mostly 50-100 μm. The MIM skill has a high finished product density due to the use of fine powders. MIM skills have the advantages of traditional powder metallurgy skills, and the high degree of freedom in shape is beyond the reach of traditional powder metallurgy. Traditional powder metallurgy is limited to the strength and packing density of the mold, and the shape is mostly two-dimensional cylindrical.

The traditional fine-casting desiccation technique is an extremely useful technique for producing disorderly shaped products. In recent years, the use of Tao Xin assists in the completion of finished products such as slits and deep holes, but the strength of the heart and the mobility of the casting liquid are constrained. There are still some technical difficulties in this skill. In general, this technique is suitable for making large and medium-sized parts. Small and messy parts are more suitable for MIM skills. Contrast Item Production Skills MIM Skills Traditional Powder Metallurgy Skills Powder Particle Size (μm) 2-1550-100 Relative Density (%) 95-9880-85 Commodity Weight (g) Less than or equal to 400 grams 10--Several Commodity Shapes 3D Messy Shapes Simple two-dimensional shape mechanical function is good or bad

Comparison of MIM process and traditional powder metallurgy The die-casting technique is used in aluminum and zinc alloys, where the melting point is low and the activity of the casting liquid is good. Due to data constraints, the merchandise of this skill has its limits in strength, wear resistance, and corrosion resistance. MIM skills can process more raw data.

Although the fine-casting skill has improved the accuracy and messiness of its products in these years, it is still inferior to the dewaxing and MIM skills. Powder casting is an important development and has been applied to the mass production of connecting rods. However, in general, the cost of heat treatment and the life of the mold in the foundry project are still in doubt and still need further processing.

The traditional mechanical processing method, and the recent advancement of its processing ability through automation, have made great progress in terms of function and accuracy, but the basic procedures still cannot be gradually processed (turning, planing, milling, grinding, drilling, polishing, etc.) ) To complete the shape of the part. The machining accuracy of machining methods is much better than other machining methods, but because the data has a low utilization rate, the end of its shape is limited to the equipment and tools, and some parts cannot be finished by machining. On the contrary, MIM can use data without restrictions. With respect to the production of small, difficult-to-shape, fine parts, MIM technology is less costly and efficient than mechanical machining, and it has strong competitive power.

MIM skills do not compete with traditional processing methods, but make up for the shortcomings of the lack of skills or the inability to make traditional processing methods. MIM skills can show its features in the category of parts made by traditional processing methods. The MIM skill has the advantage in the production of parts and components. It can form a structural part with a highly disordered structure.

Eruption Molding Skills The use of eruptors to erupt the molded product blank ensures that the material fills the mold cavity and ensures the end of the messy construction of the part. In the past, in the traditional processing skills, the method of making individual components and then composing components was used. When using the MIM skills, the entire component can be considered as a single component, which greatly reduces the process and simplifies the processing procedure. Comparing MIM and other metal processing methods, the finished product has high dimensional accuracy, no secondary processing or only a few finishing processes. The eruption molding skills can be used to directly form thin-walled and disorderly structures. The shape of the finished product is close to the final product demand. Keep around ±0.1-±0.3. In particular, it is particularly important to reduce the processing cost of hard alloys that are difficult to machine, and to reduce the loss of precious metal processing. Finished microscopic arrangement of uniform, high density, good function.

In the limiting process, due to the friction between the mold wall and the powder and between the powder and the powder, the distribution of the restricting pressure is very uneven, resulting in the limitation of the unevenness of the arrangement of the blank on the microscopic arrangement, so that the restriction of the powder metallurgy parts will be formed. During the sintering process, the non-uniformity is shortened, so the sintering temperature has to be reduced to reduce this effect, and then the finished product has large porosity, poor data density, and low density, which seriously affects the mechanical function of the finished product. On the contrary, the eruption molding skill is a fluid forming skill. The existence of the adhesive ensures the uniform distribution of the powder and then eliminates the non-uniformity of the microscopic arrangement of the blank, so that the density of the sintered product can reach the theoretical density of its data. Limiting the density of goods under normal circumstances can only reach 85% of the theoretical density. The high fineness of the finished product allows the strength to be added, the toughness to be strengthened, the ductility, the electrical and thermal conductivity to be improved, and the magnetic function to be improved. High efficiency, easy completion of mass production and scale production of metal molds for the use of MIM skills, the appropriate number of its life and engineering plastics eruption molding tool. Because of the use of metal molds, MIM is suitable for mass production of parts. The use of eruption machines to shape commodity blanks has greatly improved production efficiency, reduced production costs, and the commonness and repeatability of eruption molded products, and then provided guarantees for large-scale and large-scale industrial production. Wide range of applicable data, wide application scope (iron-based, low-alloy, high-speed steel, stainless steel, Ke valve alloy, hard alloy)

The materials that can be used for the eruption molding are very extensive. In principle, any high-temperature pourable powder material can be formed by MIM skills, including difficult-to-process data and high-melting point data in traditional manufacturing techniques. In addition, MIM can also conduct data formulation research based on the user's needs, make any combination of alloy data, and mold composite data into parts. The application fields of eruption molding products have been widely used in various fields of the national economy and have broad market prospects.

Exploitation of the function and cost of finished products

The use of micron-sized fine powders for MIM technology not only accelerates sintering and shortens, but also helps improve the mechanical function of data, extends the fatigue life of data, and improves resistance to stress corrosion and magnetic properties.

The scope of application of MIM skills includes:

1. Computer and its auxiliary equipment: such as printer parts, magnetic core, striker pin, drive parts

2. Things: such as drills, cutter heads, nozzles, gun drills, spiral cutters, punches, sleeves, wrenches, electrician stuff, hand-made things, etc.

3. Household appliances: such as watch cases, bracelets, electric toothbrushes, scissors, fans, golf club heads, jewelry links, ballpoint pen clips, and cutter blades

4 parts for medical machinery: such as dental orthodontic brackets, scissors, tweezers

5. Military components: missile tail, gun parts, warheads, drug masks, credit components

6. Electrical Parts: Electronic Packaging, Micro Motors, Electronic Parts, Sensors

7. Mechanical parts: such as loose cotton machine, textile machine, crimping machine, working machinery, etc.;

8. Cars and marine parts: such as clutch inner ring, fork sleeve, distributor sleeve, valve guide tube, synchronous hub, airbag parts, etc.