Finite Element Modeling of Milling Spindle Thermal Behavior with Variation of Bearing Preload

Bearing preload has a major influence on frictional heat generation, whereas cooling fluid substantially influences the spindle system’s heat balance. Finite element modeling was utilized to investigate the effect of bearing preload on the thermal behavior of a machine tool spindle. Both bearing heat generation and cooling fluid were applied as boundary conditions of Finite Element Method (FEM) model. The FEM analysis includes steady state and transient thermal analysis at two different spindle speeds 3000 and 15,000 rpm. Based on the analysis’s findings, it can be seen that the bearing preload changes affect the heat generation and temperature. The difference in heat generation between the minimum and maximum preload values at rotational speeds of 3000 rpm and 15,000 rpm is 9.5 W and 47.4 W, respectively. When increasing the bearing preload from EL to H at low spindle rotation speeds of 3000 rpm, the temperature rise is roughly 0.56 °C. However, at high spindle rotation speeds of 15,000 rpm, the temperature rise could reach 2.75 °C.