The basic process is as follows: first, the solid powder is mixed with the organic binder evenly, after being granulated, the injection molding machine is injected into the mold cavity for curing forming under the condition of heating plasticizing (up to 150 degrees Celsius), then the binder in the forming blank is removed by chemical thermal decomposition, the final product is obtained by Sintering Densification. Compared with traditional technology, it has the characteristics of high accuracy, uniform structure, excellent performance low production cost. Its products are widely used in electronic information engineering, biological medical devices, office equipment, automobiles, machinery, hardware, sports equipment, horological industry, ordnance aerospace industry. Therefore, it is generally believed that the development of this technology will lead to a revolution in parts forming machining technology, is known as "the most popular parts forming technology nowadays" "forming technology in twenty-first Century".

Metal powder injection molding technology is a product of many disciplines such as plastic forming technology, polymer chemistry, powder metallurgy technology metal materials science. By using injection moulded blank rapid manufacturing of high-density, high-precision, three-dimensional complex shape structural parts, the metal powder injection molding technology can quickly accurately transform the design idea into a certain structure function. It is a new revolution in the manufacturing technology industry that sex products can be directly produced in batches. The technology only has the advantages of less conventional process, less cutting less cutting, high economic efficiency, but also overcomes the shortcomings of traditional powder metallurgy products, non-uniform materials, low mechanical properties, difficult to form thin walled complex structures. It is especially suitable for mass production of small, complex special metal parts. The process flow is binders, mixing, injection molding, degreasing, sintering post-processing.

The particle size of metal powder used in MIM process is generally 0.5~20 / M; in theory, the finer the particle is, the larger the specific surface area is, it is easy to form sintering. The traditional powder metallurgy process uses coarser powder larger than 40 m.

organic adhesive

The function of organic adhesive is to stick metal powder particles, so that the mixture can be heated in the barrel of the injection machine with rheological property lubricity, that is to say, the carrier for powder flow.Therefore, the choice of the adhesive is the carrier of the whole powder. Therefore, sticking selection is the key to the whole powder injection molding. Requirements for organic adhesives:

1. less dosage less adhesive can make the mixture produce better rheological properties.

2. no reaction, no chemical reaction with metal powder during the process of removing the adhesive.

3. it is easy to remove, no carbon residue is found in WIP.

Mixture

The metal powder organic adhesive are mixed together to make all kinds of raw materials into injection molding mixture. The uniformity of the mixture directly affects its fluidity, thus affecting the injection molding process parameters even the density other properties of the final material. The injection molding process is consistent with the plastic injection molding process, the equipment conditions are basically the same. In the injection molding process, the mixture is heated into a plastic material with rheological properties in the barrel of the injection machine injected into the mold under the appropriate injection pressure to form the blank. The microstructure of injection molded blanks should be uniform uniform, so that the products can be uniformly contracted during sintering.

extraction

It is necessary to remove the organic adhesive contained in the blank before sintering. The process is called extraction. The extraction process must ensure that the adhesive is gradually discharged the different parts of the blank along the tiny channel between the grains, without decreasing the strength of the blank. The removal rate of binder generally follows the diffusion equation. Sintering can shrink the porous defatted blank into a product with certain structure properties.