Shell Molding

Mold making process metal pattern halves heated to 350-700 Deg coated with parting agent (silicone) fine sand/resin mixture applied to patterns mixture bonds to heated patterns excess sand/resin removed shells removed from patterns

Shell molds two halves clamped together wall thickness controlled by contact time 5-10 mm wall thickness decomposition of sand binder produces gas requires good venting molds may be supported by sand

Process Advantages close tolerances (.002”) less draft required thin wall sections with low temps sharp corners, small projections small cored holes smooth surfaces due to fine sand high quality finish less finishing operations

Process Disadvantages expensive pattern equip captial for shell molding machine size limitations resin bond agent adds to sand costs need high volumes to justify costs

Applications small mechanical parts requiring high precision gear housings connecting rods