A cartridge heater is a small electrical device with a metal core and a heating coil. A resistance wire of nickel chromium or nichrome is the core of the cartridge heater. The number of turns per inch around the core determines the watt density. The current flowing through the coil heats the sheath surrounding the heating coil. The insulated sheath is made of magnesium oxide or other alloy. When the resistance wire touches the sheath, it causes the heater to fail.
Heat Transfer From The Sheath To The Metal Part Is Facilitated By The Dielectric Material
A cartridge heater is composed of an outer metal enclosure, called a sheath, and a heating element, usually nickel chromium. A cartridge heater is available in a variety of designs and styles and can operate at temperatures of up to 1400F. These units can be purchased as a stock item or custom manufactured to meet specific requirements. They can be found in a variety of imperial and metric diameters, lengths, and styles.
The most popular design of cartridge heaters is a cylindrical metal block. These units are generally custom-made to meet wattage requirements. A standard diameter of the metal block will be approximately four to six inches. The heater’s interior is made of a ceramic core with a metal sheath around it. The heat transfer from the sheath to the metal part is facilitated by the dielectric material. The heater is also designed to be removable, which makes it ideal for a variety of applications.