Patent ID: 8128857

Claim:
A method of shortening the cycle time required to compression mold a roofing product of the shingle or tile type, comprising the steps of: (a) providing a carrier plate base having heat conduction capability and comprised of a material that has low receptivity to being heated by induction heating; (b) providing a carrier plate surface material having heat conduction capability and comprised of a material that has high receptivity to being heated by induction heating and is substantially thinner than the carrier plate base; (c) bonding the carrier plate surface material to the carrier plate base, to form a carrier plate; (d) moving the carrier plate to a delivering means and delivering the carrier plate to an induction heater via the delivering means and induction heating the carrier plate surface material to raise the temperature of the carrier plate surface material; (e) then delivering the carrier plate to an extruding means via the delivering means and extruding a hot, partially molten thermoplastic material onto the surface material of the carrier plate; (f) then, while the raised temperature of the carrier plate surface material keeps the extruded thermoplastic material in a partially molten state, delivering the carrier plate to a compression molding means via the delivering means and compression molding the thermoplastic material to a desired configuration while it is on the carrier plate surface material; and (g) cooling the thermoplastic material by allowing heat transfer from the surface material of the carrier plate to the base of the carrier plate.