Density of powder metallurgy processed parts

What is the general density of powder metallurgy processed parts?

This issue needs to be understood from two aspects: the production process and technical requirements of powder metallurgy parts.

Firstly, the density of powder metallurgy processed parts is related to the pressing process of powder metallurgy. The two most important processes in powder metallurgy parts processing are pressing and sintering of pressed blanks. The compression molding process is to use specialized equipment and molds for powder metallurgy parts to press mixed raw materials (such as iron powder, copper powder, and stainless steel powder) into blanks with a certain density. The density of the blank depends on the loose packing ratio and compression performance of the raw materials. Good powder metallurgy raw materials significantly increase the density, strength, and hardness of the parts. However, powder metallurgy processing technology cannot be compared to casting or die-casting parts. In general, the density of the metal slurry after cooling must exceed the density of the powder particles pressed. Therefore, in conventional production processes, the density of parts processed by powder metallurgy pressing is definitely lower than that of die-casting, casting, cold heading, and turning parts.

What are the ways to improve the density of powder metallurgy parts in the production process? There are several methods available

The compression molding adopts warm pressing process

Powder metallurgy raw materials and molds are appropriately heated to a certain temperature for pressing, and this method can compress the density to 7.3 g/cm under better raw material conditions.

Improve density in sintering process

Because during the sintering process of powder metallurgy parts, the lubricant and cutting agent additives inside the blank are first dewaxed, which forms pores. The best way to significantly increase the density of parts during sintering is to infiltrate copper during sintering. A certain amount of pure copper is introduced into the sintered billet to fill the pores, which can increase the density to 7.6 g/cm³ . In summary, I want to exceed the material and parts by 7.9g/cm³ The density is impossible.

Secondly, powder metallurgy processing of parts is closely related to the technical requirements for their use. For example, oil bearing requires a density of 6.3 g/cm³; Left and right are sufficient, because low density parts have high porosity and high oil content, which plays a good self-lubricating role. In addition, the guide, piston, bottom valve, restoring body, etc. in powder metallurgy parts for automotive shock absorbers are generally required to have a density of 6.6 grams per CM due to better usage conditions ³; That's enough. In addition, powder metallurgy transmission gears, especially automotive driven gears, which are widely used, must have a density of 6.9 g/cm³ due to their high load-bearing strength and hardness ³; Above, this can achieve the purpose of using the parts and meet the technical requirements.