Abstract: Variation in temperature leads to corresponding variation in physical dimension of mechanical parts. The conventional calculation of thermal deformation is approximate and linear, which can be applied in normal or low precision field, but has great limitation in high precision field. After years of research, it is found that when temperature changes, thermal deformation of mechanical part does not follow the conventional linear formula, but relates to the physical dimension of the form of mechanical part, which can be indicated by a nonlinear formula. Mathematical models based on the relationship between volume expansion coefficient and linear expansion coefficient of crystal materials are established to calculate thermal deformations of cylindrical shaft parts and hollow parts in steady uniform temperature field, and the effect of form factors on thermal deformation of parts is considered. Thermal deformations of different cylindrical shaft parts and hollow parts are measured by using a thermal deformation measuring device with a measurement accuracy of ±0.4μm. Experimental results show that the calculation results with the form factors considered are closer to the experimental values than those of conventional formulas.

Key words: Cylindrical shaft parts, Form factor, Hollow parts, Thermal deformation