Mica Heater Bands Construction
Mica band heaters are manufactured by enclosing a precision wound nickel-chromium resistance ribbon inside a specially treated steel sheath. Mica is used to insulate the resistance ribbon from shorting out against the outer steel sheath.
Mica band heaters are designed with nickel-chrome resistance wire precisely wound around a mica sheet, which is then placed between two additional corrosive resistant outer mica steel sheets. Mica is used because it provides good thermal conductivity and dielectric strength. It can withstand voltage spikes, resist moisture, and is flexible enough to conform to the curvatures of plastic molding machine barrels. Since mica is also a heat insulator, only top grade mica, which is inorganic, has high temperature stability, and is “paper thin” is used. This “paper thin” characteristic enables a quick transfer of heat through the mica to the outside steel sheath, thus transferring the heat away from the red hot internal resistance ribbon winding.