Pre-sintering
The main purpose of tungsten powder pre-sintering is to improve the strength and conductivity of the parison in order to facilitate high temperature sintering.

Pre-sintered tungsten billet requirements:
1. There should be no dirt, spots and other defects.
2. should be placed at dry place under room temperature , storage time should not be too long,otherwise, it will cause some problems to the second time high temperature sintering due to the oxidation of tungsten billets.

Some quality problems frequently caused in Presintering of the production, such as,: burn-out, not well-burned, become dirty and so on.
burn-out bar should be avoided during production. This issue is particularly important for WTH grades of tungsten thorium alloy billets. Because the WTH grade powder is fine equiaxed, with poor formability, compact billet strength is low.

Sintering
The sintering of metallic tungsten belongs to solid phase sintering. The purpose is to make the porous powder into a machined tungsten or tungsten alloy with a certain metal structure and properties.

We use the vacuum vertical melting furnace for tungsten billet sintering, to ensure the tungsten billet purification effect and complete volatilization of the impurities in order to
Improve the quality of  tungsten billets.
The processability is determined by the quality of the tungsten billets .Under normal circumstances, the billet with high purity, high density, grain fine and uniform, easy to be formed and processed. So the purity, density, the number of grains of the tungsten billets are strictly controlled during production to ensure the quality of the billets.

The purity of the tungsten metal powder metallurgy billet ultimately depends primarily on the purity of the powder.