Xaloy Inc., New Castle, Pa., recently began extrusion trials of its energy-saving nXheat induction heaters on extruder barrels. These heaters were first introduced last year for injection machine barrels, which don't generally require cooling, unlike extruders. Trials have been done on modified 3.5-in. and 2-in. Davis-Standard extruders. Xaloy plans to retrofit induction-heating elements in place of heater bands only on barrel sections that do not require cooling. Induction generates heat by passing electrical current through wires wrapped around preformed sections of insulating material that fit around the barrel.
The heaters generate electrical eddy currents in the barrel wall, which cause resistance heating without expending energy to heat the mass of a heater band. The induction coils themselves are only warm to the touch. Besides dramatic savings of 40% to 75% of barrel-heating energy, nXheat systems are said to provide more uniform heat and faster heat-up and cool-down. Initial target markets are extrusion of materials that require higher barrel temperatures or of shear-sensitive materials like color master batches that require more heat input from the barrel and less from viscous heating.