Abstract
In the metal cutting, generally, application of lubricant to a cutting edge is one of the methods in order to suppress temperature rise of the cutting edge by reducing frictional heat. However, the reduction in friction with lubricant disappears at higher temperature environment because of the loss of lubricant oiliness associated with temperature rise. Conversely, this reduction effect might work only in the initial stage immediately after cutting edge /work engagement because the temperature is not so high. Therefore, if the cutting duration of each blade of end-mill is shorten by limiting the cutting length per once, the cutting temperature can be suppressed to be lower than the moderate magnitude for lubrication. On the other hand, Ti-alloys with low thermal conductivity would experience quite high temperature increase during the high-speed cutting process. Therefore, it is thought that lubricant cannot be used properly with conventional cutting methods. In this study, the high-speed milling method mentioned above was used to implement the machining of Ti-alloys, and the lubricant effects of different types oils were compared from two aspects as tool wear and cutting force. As a result, when using low-viscosity synthetic ester oil, the damage to the cutting edge was suppressed most. At the same time, there was no fluctuation in cutting force by repeated machining. From this result, it was suggested that the lubricant performance, in intermittent cutting with very short cutting duration, depends on the heat resistance and permeability of the oil.
