Abstract
A new ecological-cutting fluid application in which relatively large water particles covered with thin oil ilm are sprayed on a machining point was developed and is being modified by authors. This method is called an Oil-on-Water drop cutting fluid; abbreviating to "OoW". The OoW achieves both effective lubrication and strong cooling performance as well as conformability to environmental issue. An oil mass ratio to the OoW cutting fluid is only around 1%. That is, the OoW cutting fluid almost consists of water, and then it should be said that effects of water properties on cutting performance is worth investigating. In this paper it is noted how calcium concentration in water, which roughly represents hardness of water in the case of tap water, influences cutting performance. For this purpose variation of cutting force with the hardness of water is experimentally investigated on two kinds of oil. In the case of vegetable oil the cutting force is considerably reduced with the hardness of water while, in the case of synthetic biodegradable ester with surface active agent, the hardness of water has almost no influence.
