The surface temperature of the component itself in dry air is usually about 100 degrees higher than the furnace temperature. Therefore, when designing components, attention should be paid to their operating temperature. When the operating temperature exceeds a certain limit, the oxidation amount of the component itself increases, and the heat resistance decreases. Especially for iron chromium aluminum electric heating wire components, the result is easy deformation, collapse, and even fracture, which shortens the service life.

Under normal conditions, the maximum operating temperature of the component should have a wire diameter of no less than 3mm and a flat strip thickness of no less than 2mm. A series of electric heating alloys such as iron chromium aluminum electric heating wires and nickel chromium electric heating wires have different chemical compositions. The differences in oxidation resistance and electrical resistivity determine the length of service temperature and lifespan. In the data of iron chromium aluminum electric heating alloy, the component that determines the electrical resistivity is AL element, while in the data of nickel chromium electric heating alloy, the component that determines the electrical resistivity is Ni element. At high temperatures, the oxide film generated on the surface of alloy components also ages and damages from time to time. The internal elements of its components are constantly consumed. For example, ALNi can shorten its service life. Therefore, when selecting the diameter of nickel chromium wire, larger specifications of wire or thicker flat strips should be used. There is also a considerable relationship between the maximum operating temperature of the component and the wire diameter of the component. However, the presence of corrosive atmospheres often affects the operating temperature and lifespan of components. There is also a considerable relationship between the corrosive atmosphere inside the furnace and the maximum operating temperature of the components.