What are the two basic methods used in metal powder injection molding?

In the process of metal powder injection molding, why should we use fine powder as the raw material? Usually, which are the two basic methods of zcmim powder metallurgy factory below for you to answer:

1) small particles, large surface area, the higher the surface, can improve the power of sintering of powder;

2) grain refinement, the increase of the coupling force between the particles, improve the strength of the body after the skim;

3) fine particle resistance, melt and binder in the flow is not easy to separate, easy to mix and injection.

Thermal and solvent are usually used. The solvent debinding in injection molding to form an open pore network and subsequent thermal debinding of decomposition product discharge with mass transfer channel for the decomposition products may form the inner pressure and the chances of debinding defects caused by, degreasing speed.

Pressure sintering and microwave sintering

Pressure sintering of powder pressing billet heating and also the pressure can be obtained than atmospheric firing crystalline particle more fine, more dense sintered body, people commonly used heat pressure, sinter hip sintering preparation high performance stainless steel. The results show that the pressure accelerates the flow and particle rearrangement of the liquid phase, the greater the pressure, the greater the densification rate, and the close to full densification of the stainless steel after hot and so on.

Microwave sintering, which is a kind of fast sintering technology, which is used to realize the densification of the sintered body by sintering temperature and sintering temperature by using the dielectric loss of the material in the microwave electromagnetic field. In sintering process, microwave sintering can quickly jumped over the surface diffusion stage, the grain to not grow up to complete densification and rapid cooling, so it for grains in sintering process control of growing up is a kind of effective method.

Warm press forming and cold press forming

Due to the stainless steel powder is hard and poor compression, room temperature compression molding forming, required to suppress higher pressure, on the press and die, higher requirements and sintered products elastic aftereffect is serious, low density and only of preparation of simple shape parts. Warm compaction is a process of mixing and heating the powder and special lubricant to a certain temperature.

Compared to cold pressure forming, it can with lower pressure to obtain higher pressure on the green density and strength and can reduce the elastic aftereffect. Temperature and pressure conditions, powder plastic deformation enhanced, and improve green density; at the same time lubricant in under the temperature of warm compaction was semi solid, the liquid phase composition will flow in the pore by the grain boundaries, thereby increasing the particle contact.

4 major issues of PIM Technology

In the late 90s, there were nearly 300 PIM factories running around the world. However, the real problem is slowly emerging, how to solve the following 4 issues became the key to PIM!

1 defect control: how can we eliminate weld marks, cracks, voids, and other defects?

2 improve process yield: when you form a yield of only 80%, it is difficult to be profitable.

3 dimensional control: as far as possible to achieve the same size, the same shape of the product.

4 carbon control: bonding agent is very easy to pollute the product, so it is difficult to achieve the specific requirements of the carbon content of heat treatment steel; therefore, even today, low carbon stainless steel is very difficult to do it out of PIM.

What are the criteria for PIM binder selection?

After a long period of exploration, it was found that the key factor of PIM was the selection of adhesive. Powderinjection molding (PIM) of the binder should at least meet the 5 conditions:

1 in molding temperature, the additive is usually a short polymer filler, has a lower viscosity;

2 in the heating process, to maintain the same shape of green polymer backbone;

3 small molecular weight, avoid residual stress and deformation, easy to combine with the surface of solid powder;

4 the surface of the solid powder can be ensured to have good wetting property with the auxiliary agent, so that it can be combined well and not easily separated;

5 the price is not expensive, environmental protection, low water absorption.

Metal powder injection molding technology industry

Metal powder injection molding as a kind of advanced manufacturing technology, combined with the powder metallurgy and plastic injection forming technology has the advantages of limitations, breaks through the traditional metal powder die pressing forming process on the shape of the products. Has become the main processing method of precision devices. Among them, the automotive industry accounted for a significant proportion of the MIM industry each year, the global sales of 15 billion U. s.dollars. In Europe, the proportion is 45%, in North America, only 20%, while in Japan, only 18%.

With the continuous development of MIM, MIM technology can system for the processing of different materials, from low alloy steel, stainless steel to difficult to machining high temperature alloy steel. Therefore, MIM may replace the traditional machining and casting process. Compared with the traditional metal processing, its main advantage is that, as a kind of near net shape forming process can produce complex shape parts, can maximize the preparing the final shape of the parts without subsequent machining or only need to use the least amount of machining; material utilization rate is high, suitable for mass production.

MIM parts are first applied to the small displacement diesel engines of Europe and the United States diesel light truck engine. Now this technology has been widely used in the global car, mainly for the production of fuel system components, such as the jet nozzle and the armature.

The effect of steam treatment on powder metallurgy products

After simple processing of powder metallurgy products using the steam, you can get ideal anticorrosive property, because the iron atoms on the surface of the oxidation reaction with steam, to produce a layer of oxide film, anti rust performance of the products is therefore improved a lot. And because of the hardness of the film is very high, so once after the adhesion on the surface of a product, its abrasion resistance and wear resistance will change.

Powder metallurgy products have an important role in the steam treatment, that is, sealing holes. In addition, the effect of the powder metallurgical products after steam treatment on the dimensional accuracy is not very large. The whole process will not pollute the environment, and the energy consumption is not high.