High Speed grinding with CBN Wheels

摘要

Over the last 20 years a great deal of intellectual energy and research has been focussed on high speed grinding of ferrous metals with CBN. The very term "high speed" has been a shifting target for machine tool builders. In 1980 80m/s was considered exceptional, today speeds up to 500m/s have been reported in research [1] and several production grinders are capable of 200m/s. For the purpose of this presentation high speed will be considered, somewhat arbitrarily, to describe processes in the range of (100 - 200)m/s using plated and vitrified CBN wheels.High speed grinding has been driven by promises of higher stock removal rates and/or longer wheel life. However, like most new technologies, much was made at first of the potential benefits, whilst only more recently are the limitations and pitfalls being identified in order to put the technology to practical use. The increased cost of equipment purchase and maintenance can make the technology hard to cost justify, while burn or coolant hydrodynamic issues may not allow the desired part quality to be achieved. High stock removal rates associated with higher speeds can only provide a significant benefit if they represent the majority of the cycle time (e.g. rough grinding), or they allow capital equipment benefits (e.g the elimination of manufacturing steps or reduction in numbers of machines required), or they simplify and/or provide more flexibility in processing. The potential for much higher wheel life offered by higher speeds can only be a tangible benefit if the wheel grade is not compromised because of thermal damage issues. On the other hand, in some applications such as high-speed contour grinding, it can open up totally new ways of processing a component.