TABLE OF CONTENTS Machining and measuring operations are invariably accompanied by relative vibration between workpiece and tool. These vibrations are due to one or more of the following causes: (1) inhomogeneities in the workpiece material; (2) variation of chip cross section; (3) disturbances in the workpiece or tool drives; (4) dynamic loads generated by acceleration/deceleration of massive moving components; (5) vibration transmitted from the environment; (6) self-excited vibration generated by the cutting process or by friction (machine-tool chatter).
The tolerable level of relative vibration between tool and workpiece, i.e., the maximum amplitude and to some extent the frequency, is determined by the required surface finish and machining accuracy as well as by detrimental effects of the vibration on tool life (see The Effect of Vibration on Tool Life) and by the noise which is frequently generated.
This chapter discusses the sources of vibration excitation in machine tools, machine-tool chatter (i.e., self-excited vibration which is induced and maintained by forces generated by the cutting process), and methods of control of machine-tool vibration.
Hard spots or a crust in the material being machined impart small shocks to the tool and workpiece, as a result of which free vibrations are set up. If these transients are rapidly damped out, their effect is usually not serious; they simply form part of the general "background noise" encountered in making vibration measurements on machine tools. Cases in which transient disturbances do not decay...
