The difference of metal powder injection machine and injection machine.

The structure of powder injection machine and plastic injection machine is similar, but when plastic formed, due to some plastic will be swell after ejected, the size of actual cavity is rather smaller than final parts. The size of the MIM injection molding cavity is determined by the sintering shrinkage rate. Among the expand quantities of injection is up to by solid powder content and sintering shrinkage rate. In addition, the deformation of sintering is caused by distribute powder. The existing of shrinkage and deformation ask that powder injection molding should have more advanced mold design than plastic injection molding, to reduce the defects during process. 

The biggest difference of MIM and plastic injection molding is the difference of injection material, the plastic have high liquidity after heat plasticization in injection machine, but the liquidity of MIM material is poor, the size shape and position of gate will have a very important influence for forming. The unsuitable gate design will lead to shrinkage holes, jet, weld line, trachoma and other defects.

The influence of melt temperature of injection material and injection speed rate is relative small, the wave direction is same and flat, the curve has a slight upward trend, when get a certain gate size, the influence of process parameter on the flow length is the same as that of the injection forming process. 

In recently, the metal injection molding machine are mostly use tradition plastic injection machine. Because the material of metal powder injection molding is multiphase mixture with difference density, especially in melting step, because of big density of metal, using tradition reciprocating injection machines, it will lead to metal stay in the bottom because of gravity work, let the density of green parts is not uniform.

Now, this industry will invent a dynamic forming machining technology of a kind of polymer and equipment. Its theory is to introduce the mechanical vibration force field caused by electromagnetic or electro-hydraulic into the polymer injection molding process, and achieve to speed uniform mixing ,plastic, to ensure the uniformity of the material being printed.