Isostatic Pressing

ISOSTATIC PRESSING

In isostatic pressing method, a uniform pressure is applied on all sides.

The raw material is filled in rubber mold and it is sealed with plate and metal mandrel. The sealed rubber mold is inserted into liquid.

The liquid is kept inside the pressure vessel and preferably noncompressible. The top of the pressure vessel is closed after inserting the rubber mold.

A hydraulic pressure is applied to the liquid and hence, the uniform pressure is experienced by the rubber mould in all directions. The friction of rubber mould with the walls is eliminated, which results in a uniform density of compacted material.

By removing the pressure, the rubber mould is taken out. The compacted material is removed by removing the mould sealed plate and metal mandrel. bild

The compacted materials are then subjected to densification resulting in more uniform shrinkage with less wrapping and cracking.

There are two different methods of isostatic pressing

 (i) wet-bag

(ii) dry-bag processing

In wet-bag processing method, raw material is filled in flexible rubber mold, sealed and then poured isostatically. The experimental set-up is shown in Fig. 4.22. The pressure applied in laboratory experiment process ranges from 35 to 1380 MPa.

However, in industry, the production units normally operate at a pressure of 400 MPa or even less.

This method is widely used for production of variety of products and sizes. The main disadvantages of this method are long cycle time, high labour requirements and low production rates.