Abstract: The penetration mechanism and cutting force under minimum quantity lubrication (MQL) cutting is presented. The performances of traditional cutting, dry machining and MQL in the milling of high strength steel (PCrNi3Mo) are compared, and the effect of MQL on tool wear and chip formation is discussed. The effect of cutting parameters (cutting speed, feed rate, depth of cut and lubricant quantity) on tool wear under the MQL cutting environment is investigated. Based on response surface methodology, a tool flank wear model is built and experimentally verified in order to determine the best oil usage. The experimental results show that MQL provides some advantages in terms of tool wear reduction. The tool flank wear model has the better reliability and practical value. MQL with 185 mL/h provides the lowest flank wear when milling high strength steel (PCrNi3Mo). Lower cutting temperature and favorable change in chip deformation can be obtained under MQL conditions mainly through reduction in the cutting zone friction.

Key words: Chip formation, Mechanism, Minimum quantity lubrication, Model, Response surface methodology, Tool wear