Introduction To The Production Process Flow Of Powder Injection Molding

With the acceleration of technological progress and innovation, products are gradually moving towards miniaturization and miniaturization, greatly driving the development of micro processing technology. Compared with other micro machining processes, powder injection molding technology has advantages such as a wide range of material applications, the ability to produce complex shapes, and the ease of achieving large-scale production of precision micro structured parts.

Powder injection molding can be divided into ceramic powder injection molding and metal injection molding
Powder injection molding process: feed preparation, injection molding, degreasing, and sintering
1. Feed preparation is the most critical step, as the defects introduced in this step cannot be eliminated in the subsequent process. Among them, the binder, as the core part of the feeding, directly affects the uniformity and formability of the feeding, thereby affecting the subsequent process and the performance of the final product.
The injection molding process can be simply described as: first, heating the feed to the melting temperature, then applying pressure to allow the solution to enter the mold cavity, and then cooling and forming in the mold cavity.

 

Since the emergence of MIM technology, various MIM process paths and degreasing methods have been formed with different binder systems. The degreasing time has been shortened from the initial few days to the current few hours. From the degreasing steps, all degreasing methods can be roughly divided into two categories: one is the two-step degreasing method. The two-step degreasing method includes solvent degreasing+thermal degreasing, siphon degreasing - thermal degreasing, etc.
4. Sintering is the final step in the MIM process, which eliminates the pores between powder particles and enables the MIM product to achieve full density or near full densification. In metal injection molding technology, due to the use of a large amount of binders, the shrinkage during sintering is very large, and the linear shrinkage rate generally reaches 13% -25%, which poses a problem of deformation control and dimensional accuracy control.