Cold isostatic pressing principle

Cold isostatic pressing is a forming method of cemented carbide powder, the powder forming process is similar to pressing forming, but due to the different pressure transmission methods, the density distribution and forming pressure of cold isostatic pressing billet are more advantageous than general molding.

2023-10-13 14:28:07Wang Xuemei427

Powder forming process

1. The initial powder porosity is large, the forming pressure is small, and the powder particles are mainly migrating and re-accumulating

2. In the middle stage, as the porosity decreases, the extrusion between the powders intensifies, and the powder flows and fragments locally.

3. In the later stage, the pressure reaches ** and reaches the densification stage.

Pressure and density distribution in cold isostatic pressing:

The density distribution of isostatic pressing billet is uniform along the longitudinal section. However, along the same transverse section of the billet, due to the influence of internal friction between the powder particles, the density of the billet gradually decreases from the outside to the inside.

The pressing curve of cold isostatic pressing is above the general molding curve, which means that cold isostatic pressing can make the pressing billet obtain a higher density under less pressure. This is because the powder does not move relative to the mold wall during isostatic pressing, and will not be lost by the friction of this part. This has a great advantage over molded pressing. In molded pressing, no matter what kind of pressing, in addition to the difficulty of controlling the density distribution of the billet, the pressure loss caused by the friction of the powder against the mold wall is unavoidable, even when lubrication is used.