Nickel chrome wire is a kind of non-magnetic alloy of nickel and chromium, it is widely used in heating elements. The maximum operation temperature of the heating elements is related to the wire diameter, it is better to choose thicker wires, the corrosive atmospheres also have a considerable relationship with the maximum operation temperature. The surface temperature is about 100C higher than the inner normally, when the operation temperature exceeds the limit, the oxidation of heating elements itself is accelerated, the heat resistance will be reduced, which is easily deformed,collapsed and even appreas to be broken, thereby shortening the service life.