The Use of Increased Wheel Flexibility to Improve Chatter Performance in Grinding

Abstract

The metal removal rates attainable during grinding may often be limited by the onset of an unstable vibration, commonly called regenerative chatter. Chatter is a self-induced vibration which leads to increased power consumption, a poor, generally unacceptable, ***workpiece surface finish, uneven wear of the grinding wheel and, in some cases, actual damage to the wheel. It is known that chatter is more likely to occur when the grinding wheel is hard and for this reason chatter often develops when grinding with diamond or cubic boron nitride (CBN) wheels, whose chief characteristic is that they are very hard-wearing. This paper describes the development of a technique for suppressing chatter which is particularly applicable to the use of diamond and CBN wheels. It has been predicted theoretically and confirmed by experiment that chatter may be suppressed, or even eliminated, by increasing the radial flexibility of a grinding wheel, whilst at the same time maintaining high values of the wheel's natural frequency and damping. It has been shown that the increased flexibility may be achieved by mounting the abrasive rim of the wheel via a flexible coupling, or by manufacturing a wheel by conventional means but with a flexible hub material. Both techniques are successful and diamond and CBN wheels, manufactured to these designs, have performed substantially better than conventional ultra-hard abrasive wheels currently marketed. It is considered that the problem of chatter when using diamond or CBN wheels has been solved. Since this problem has represented one of the major obstacles to the acceptance of CBN wheels by industry, it is anticipated that these wheels will now enjoy a much more widespread usage.