Patent ID: 8247747

Claim:
An apparatus for plasticizing resinous material, comprising: an electrically conductive barrel having a longitudinal axis, along which material moves axially from an inlet to an outlet; a rotatable screw disposed within and cooperating with an inner wall of said barrel, said screw adapted for plasticating resinous material fed into said barrel through said inlet as a solid, the screw having a length longitudinal axis and a main flight having a pitch arranged helically on and extending radially from a core of the screw forming a channel; a primary heating system comprising at least one laminated ceramic heater deposited on said barrel by plasma spraying having a longitudinal length along the longitudinal axis of the barrel, the ceramic heater having an electrical insulating layer interposed between a ceramic heater layer and an outer wall of the barrel, said laminated ceramic heater layer comprises a mixture of titania and ductile metal proportioned to have a coefficient of thermal expansion approximating a coefficient of thermal expansion of said barrel and wherein said primary heating system comprises a plurality of laminated ceramic heater layer stripes arranged in a spiral configuration around the longitudinal axis of the barrel, and at least one of said laminated ceramic heater layer stripes has a pitch different from an adjacent heater layer stripe in order to avoid obstructions on said barrel; the longitudinal length of the ceramic heater is arranged over a portion of the screw length; and a secondary heating system arranged at least in part over said primary heating system.