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Manufacturer of cemented carbide tungsten cobalt alloy metal injection molding
发布时间: 2021-01-30 09:07:59 次浏览 分享:

1. Process characteristics of metal powder injection molding technology. Metal powder injection molding technology is a product that integrates plastic molding technology, polymer chemistry, powder metallurgy technology and metal material science and other disciplines. The mold can be used to inject and form blanks. Through sintering to rapidly manufacture high-density, high-precision, three-dimensional and complex-shaped structural parts, design ideas can be quickly and accurately materialized into products with certain structural and functional characteristics, and parts can be directly mass-produced. This is a new development in the manufacturing technology industry. change. This process technology not only has the advantages of fewer conventional powder metallurgy processes, no cutting or less cutting, and high economic efficiency, but also overcomes the shortcomings of traditional powder metallurgy products, uneven materials, low mechanical properties, thin walls, and complex structures. It is especially suitable for mass production of small, complex and special metal parts. This picture is provided by registered user "Jane", copyright notice feedback


Manufacturer of cemented carbide tungsten-cobalt alloy metal injection molding (Figure 1)


 2. Technical process of metal powder injection molding Binder → mixing → injection molding → degreasing → sintering → post-processing.


 1. Powder metal powder The particle size of the metal powder used in the MIM process is generally >0.5~20>μ>m>; theoretically, the finer the particle, the larger the specific surface area, and it is easy to form and sinter. The traditional powder metallurgy process uses coarser powder larger than >40>μ>m>. >

Manufacturer of cemented carbide tungsten cobalt alloy metal injection molding(图1)

 2. Organic adhesive The role of organic adhesive is to bond metal powder particles, so that the mixture has rheology and lubricity when heated in the barrel of the injection machine, that is, the carrier that drives the powder to flow. Therefore, the choice of binder is the carrier of the entire powder. Therefore, the sticky pull selection is the key to the entire powder injection molding.


Requirements for organic adhesives:


 1) Less dosage and less adhesive can make the mixture produce better rheology;


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


 3) Easy to remove, no carbon remains in the product.


 3. Mixing Mix the metal powder and the organic binder uniformly to make all kinds of raw materials become mixtures for injection molding. The uniformity of the mixture directly affects its fluidity, thus affecting the injection molding process parameters, as well as the density and other properties of the final material. The injection molding process is the same in principle as the plastic injection molding process, and the equipment conditions are basically the same. In the injection molding process, the mixture is heated in the barrel of the injection machine into a plastic material with rheological properties, and injected into the mold under appropriate injection pressure to form a blank. The injection molded blank should be uniform in microscopic view, so that the product shrinks uniformly during the sintering process.


 4. Extraction The organic binder contained in the blank must be removed before sintering. This process is called extraction. The extraction process must ensure that the adhesive is gradually discharged from different parts of the blank along the tiny channels between the particles without reducing the strength of the blank. The removal rate of the binder generally follows the diffusion equation. Sintering and sintering can shrink the porous degreased blank to be densified into a product with a certain structure and performance. Although the performance of the product is related to many process factors before sintering, in many cases, the sintering process has a great and even decisive influence on the metallographic structure and properties of the final product.


 5. Post-processing For parts with more precise dimensions, necessary post-processing is required. This process is the same as the heat treatment process of conventional metal products.


 3. Characteristics of MIM process. Comparison between MIM process and other processing processes. The particle size of the raw powder used in MIM is >2-15>μ>m>, while the particle size of the original powder in traditional powder metallurgy is mostly >50-100>μ >m>. >MIM> The finished product of the process has a high density due to the use of fine powder. The >MIM> process has the advantages of the traditional powder metallurgy process, and the high degree of freedom in shape cannot be achieved by the traditional powder metallurgy. Traditional powder metallurgy is limited to the strength and filling density of the mold, and the shape is mostly two-dimensional cylindrical. The traditional precision casting de-drying process is an extremely effective technology for producing products with complex shapes. In recent years, the use of ceramic cores can be used to complete the finished products with slits and deep holes, but it is restricted by the strength of the ceramic core and the fluidity of the casting liquid. , The process still has some technical difficulties. Generally speaking, this process is more suitable for manufacturing large and medium-sized parts, while the MIM> process is more suitable for small and complex-shaped parts. Compare items Manufacturing process>MIM>Process traditional powder metallurgy processPowder particle size>(>μ>m)2-1550-100>relative density>(%)95-9880-85>product weight>(g)>less than or equal to >400>grams>10->hundreds of product shapes, three-dimensional complex shapes, two-dimensional simple shapes, mechanical properties. The MIM process and the traditional powder metallurgy method are compared with the die-casting process used in aluminum and zinc alloys with low melting point and good casting liquid fluidity. Due to the limitation of materials, the products of this process have limited strength, wear resistance and corrosion resistance. >MIM> The process can process more raw materials. Although the precision and complexity of its products have improved in recent years, the precision casting process is still not as good as the dewaxing process and the MIM> process. Powder forging is an important development and has been applied to the mass production of connecting rods. However, generally speaking, the cost of heat treatment and the life of the die in the forging process are still problematic, which still needs to be resolved. Traditional mechanical processing methods, recently relying on automation to improve their processing capabilities, have greatly improved in effect and accuracy, but the basic procedures are still inseparable from gradual processing (> turning, planing, milling, grinding, drilling, polishing Etc.>) to complete the part shape. The machining accuracy of the machining method is far superior to other machining methods, but because the effective utilization rate of the material is low, and the completion of its shape is limited by equipment and tools, some parts cannot be completed by machining. On the contrary, MIM can make effective use of materials, without restriction, for the manufacture of small and difficult-to-shape precision parts. Compared with mechanical processing, MIM process has lower cost and higher efficiency, and has strong competitiveness. MIM technology is not to compete with traditional processing methods, but to make up for the technical deficiencies of traditional processing methods or defects that cannot be produced. >MIM> technology can give full play to its specialties in the field of parts made by traditional processing methods. The technical advantages of MIM technology in parts manufacturing can form structural parts with highly complex structures. The injection molding process technology uses the injection machine to inject the product blank to ensure that the material fully fills the mold cavity, which also ensures the realization of the highly complex structure of the part. In the past, in the traditional processing technology, individual components were first made and then combined into components. When using MIM technology, it can be considered to be integrated into a complete single part, which greatly reduces steps and simplifies processing procedures. The comparison of MIM and other metal processing methods has high dimensional accuracy, and no secondary processing or a small amount of finishing is required. The injection molding process can directly mold thin-walled and complex structural parts. The shape of the product is close to the requirements of the final product, and the dimensional tolerance of the parts is generally maintained at about ±0.1->±>0.3>. Especially for reducing the processing cost of hard alloys that are difficult to machine, and reducing the processing loss of precious metals is of great significance. The product has uniform microstructure, high density and good performance. In the pressing process, due to the friction between the mold wall and the powder and between the powder and the powder, the pressing pressure distribution is very uneven, which leads to the uneven microstructure of the pressed blank, which will cause the pressed powder metallurgy parts to be The shrinkage is not uniform during the sintering process, so the sintering temperature has to be lowered to reduce this effect, so that the product has large porosity, poor material compactness, and low density, which seriously affects the mechanical properties of the product. On the contrary, the injection molding process is a fluid molding process. The presence of the adhesive ensures the uniform distribution of the powder so as to eliminate the unevenness in the microstructure of the blank, so that the density of the sintered product can reach the theoretical density of its material. Under normal circumstances, the density of the pressed product can only reach 85% of the theoretical density. The high compactness of the product can increase the strength, strengthen the toughness, improve the ductility, electrical and thermal conductivity, and improve the magnetic properties. High efficiency, easy to achieve mass and large-scale production. The metal mold used in MIM technology has a life equivalent to that of engineering plastic injection molding tool molds. Due to the use of metal molds, it is suitable for mass production of parts. Since the injection molding machine is used to form the product blank, the production efficiency is greatly improved, the production cost is reduced, and the consistency and repeatability of the injection molded product are good, thereby providing a guarantee for mass and large-scale industrial production. Wide range of applicable materials and wide application fields (>iron-based, low-alloy, high-speed steel, stainless steel, gram valve alloy, cemented carbide>). There are a wide range of materials that can be used for injection molding. In principle, any powder material that can be cast at high temperature can be part of the MIM process, including difficult-to-process materials and high-melting materials in traditional manufacturing processes. In addition, MIM can also conduct material formulation research according to user requirements, manufacture alloy materials in any combination, and shape composite materials into parts. The application fields of injection molded products have spread across all fields of the national economy and have broad market prospects.


4. Technical application fields of metal powder injection molding technology


 1. Computer and its auxiliary facilities: such as printer parts, magnetic cores, firing pin, drive parts;


2. Tools: such as drill bits, cutter heads, nozzles, gun drills, spiral milling cutters, punches, sockets, wrenches, electrical tools, hand tools, etc.;


3. Household appliances: such as watch cases, bracelets, electric toothbrushes, scissors, fans, golf heads, jewelry chains, ballpoint pen clamps, cutting tool bits and other parts;


 4. Parts for medical machinery: such as orthodontic frames, scissors, tweezers;


5. Military parts: missile fins, gun parts, warheads, charge covers, fuze parts;


 6. Electrical parts: electronic packaging, micro motors, electronic parts, sensor parts;


7. Mechanical parts: such as cotton loosening machine, textile machine, curling machine, office machinery, etc.;


8. Automobile and ship parts: such as clutch inner ring, fork sleeve, distributor sleeve, valve guide, synchronization hub, airbag parts, etc.