The Vacuum Moulding or V-Process
 
This moulding process is based on generating a vacuum when a thermo-plastic contour foil is deep drawn over an appropriately prepared pattern, in order to maintain the mould shape in sand without binding material, right through the stages of pouring, cooling and emptying.

The V-Process Stages
 
Heated plastic foil is drawn using vacuum over a pattern provided with a series of apertures and mounted on a closed box from which the air can be evacuated (Figs. 1+ 2).
 

The mould box is placed onto the vacuum box with the pattern in position (Fig. 3).

Fine grained, quartz sand free of binding material is filled into the mould and compacted by vibration. (Fig. 4).
 
After applying the foil cover, air is extracted from the sand so that the mould becomes firm. To release the mould, the vacuum is replaced by a small amount of pressure. (Figs. 5 + 6).
 
During and after pouring, the mould remains connected to the vacuum system. (Fig. 7).

Only when the mould is to be unloaded is the vacuum released.
The sand and the casting fall free of the cast. No additional force is required (Fig. 8).