Abstract: A temperature controlled electric heater for severing a web of vinyl film which includes a plastic coated metallic sheath having internal heater elements arranged in a ceramic core and a thermal resistance element nested in the core and in surface contact with the sheath for sensing the temperature of the heater; and means for securing the heater rigid and aligned with a web of vinyl film, said web being held under tension, and the heater being adapted to heat sever the film on contact with the web when the web is drawn over the heater.

Abstract: An electrical heating mat comprises an electrical resistance heating wire arranged in a loop formation with substantially straight leg portions between curved portions. A plurality of spaced apart spacer strips made of thermoplastic material are provided to hold the heating wire its looped formation. Each spacer strip comprises an elongated narrow strip body having a plurality of spaced open-sided were receiving loops having an inner dimension assuring snap-fit reception of the wire therein. One end of each strip body is provided with a snap-in coupling member dimensioned to snap-fit into a wire receiving loop at the end of an adjacent spacer strip to enable a plurality of mats to be interconnected together to form a larger unit. Spacer lands extending generally parallel to the leg portions of the heating wire may connect the spacer strips together.

Abstract: An electric heater having a ceramic core with a heating element surrounding the core and a jacket surrounding the heating element such that the heating element is secured to the jacket but there is no chemical bonding between the heating element and the core. In the method of producing the electric heater, the core is formed in an uncured state and then surrounded with the heating element. The heating element is surrounded by a jacket such that the heating element is secured to the jacket, and the core is thereafter cured.In producing an article such as the core of the heater from a thermosetting type material, the material is preheated to within a range so as to soften the material sufficiently for injection into a mold. The mold is preheated to a temperature sufficient to cure the material after injection into the mold.