The lost foam process uses sand as it primary molding media. Unbonded sand is used to support and rigidize the coated foam pattern in the flask during casting.

• The permeability of the sand is important to allow gasses and foam residue to escape from the cavity during pouring.  The sand size and the compaction density are controlled to give the desired permeability in the sand.

• The cylinder block pattern is positioned horizontally in the flask.  Loose silica sand is back filled into the flask and compacted by vibration on a 3-stage horizontal shaker table. 

• The sand must be loaded and compacted uniformly in the flask to prevent cluster distortion and deformation.