In the next stage the cakes are transferred to a de-airing pug mill attached with vacuum chamber. The cakes are fed into the pug mill through a hopper, get pugged, simultaneously the entrapped air from the cakes is also removed by vacuum process. This improves the plasticity and workability of the final plastic body. It is a general process technique to allow the pressed cakes to stand in damp cellars for long time as much as possible. By this the colloidal material absorbs the water and swells. This phenomenon improves the plasticity of the body.
The entire operations from filter press to de-airing pug mill are mostly mechanized in all factories and has simplified the handling operations. The pugged clay is carried forward and recompacted before extrusion through a die. The size of the extruted plastic cylinders varies depending upon the size of the final ware and the process where by the shaping is done.
