Coil heaters are most frequently used for plastic injection or molding machine. Coil heaters are designed to melt plastic in a hot runner molds. The coil heater design allows for heat transfer in a 360 Degree area allowing for optimum heat transfer inside the mold. In order for the Coil heater to get it’s spring shape it is heated and then slowly cooled to allow for it to be molded and shaped. Although there is some spring back that occurs it is usually only .001-.002″ and can be corrected by shaping it to a undersized mandrel. These heaters can allow up to 106 Watts per square inch and can reach operating temperatures of 1200 Degrees Fahrenheit or around 649 Degrees Celsius.

The coil heaters unlike cartridge heaters fit around a hot runner nozzle in which the plastic flows through the coil instead of a cartridge heater where the plastic flows around the heated area. Coil heaters are also designed not in a convention radius but also designed to be flat and this design allows for a higher transfer of heat to the metal and the thermoplastic material. Both heaters are rolled from 430 Stainless steel and about a 1/4 inch thick.

They are also designed to have any style and angle exit to fit any mold cavity. Just like all other heaters they can be incorporated with internal J type or K type thermocouples to measure the heat accurately so that the control of a even stable melt of the plastic is achieved. As well as thermocouples different leads and sheathings can be applied. For high heat Teflon is usually the choice of lead time and also can be accompanied by braided metal leads or armor leads. Coil heaters are more expensive than the conventional band heater but have a long life span.