Energy efficiency improvement of machine tool spindle cooling system with on–off control

Spindle cooling systems are essential to suppress the thermal displacements of machine tools. However, they are one of the main energy consuming units in machine tools. Therefore, the trade-off between their energy efficiency and thermal displacement needs to be investigated and relevant mitigation methods developed. This paper proposes an on–off cooling method that reduces the energy consumption of a hot-gas-bypass type spindle cooling system with minimal thermal displacement of machine tools. Evaluations conducted on two machine tools (specifically, a vertical machining center and a turn-mill center) verify that the proposed method enables the cooling system to operate more energy efficiently.