Influence of clearance angle on micro/nano structure fabrication in elliptical vibration cutting of hardened steel

Surfaces textured by sophisticated micro/nano structures can provide advanced and useful functions and features as compared with simply smooth surfaces. To promote widespread use of the structured surfaces, manufacturing technology of structured surfaces for ultra-precision dies and moulds made of hardened steel is absolutely essential. Conventional diamond cutting is not applicable to machining of steel due to rapid tool wear and surface deterioration. On the other hand, elliptical vibration cutting (EVC) equipped with the ultra-precision amplitude control sculpturing method is considered as a potential candidate for the functional surface fabrication on steel materials. In this method, tool geometry, especially the clearance angle, imposes a limit on the machinable part geometry due to the flank face contact to the target shape in the downhill machining. In order to clarify the influence of flank face contact on the machining accuracy and the tool wear, a series of theoretical and experimental investigations are conducted in this paper. A surface with micro sine-sweep profile is fabricated on hardened steel by applying the proposed amplitude control sculpturing method. It verified that the interference between flank face and fabricated structure causes not only the serious machining accuracy deterioration but also the serious tool damage due to the enhancing of ploughing process.