[6] The nichrome wire is wound around a ceramic core, and the number of spirals per inch vary according to the requested watt density.

The sheath is the part of the cartridge heater which makes contact with the material or substance to be heated.

Several metal alloys are used, depending on the type of application, such as highly acidic or corrosive environments.

[9] Depending on the clearance and the design of the machine where the cartridge heater will be inserted, the type of wire used will vary.

Fiberglass is the commonly used for cartridge heaters and other high-temperature applications,[10] such as automotive wiring harnesses and industrial equipment.