Thermostatic bimetal is a kind of composite material which consists of two or more layers and each layer is provided with a different expansion coefficient. The layer which possesses higher expansion coefficient is called the master layer. The layer which possesses lower expansion coefficient is called the passive layer. The layer between them is called buffer layer which acts as an adjusting resistance. Thermostatic bimetal strip will be bent or turned because of their different expansion coefficients while the ambient temperature changes. Thermostatic bimetal is mainly applied for manufacturing temperature sensing elements in automatic control equipments and instruments for temperature control, temperature compensation, current restriction and temperature indication.