Ultrasonic Techniques

Abstract

Since the early nineteen-fifties many investigations have been made into the application of oscillatory energy to metal working processes¹. Claims were made that the oscillations, which in some studies were at ultrasonic frequencies and in others at sub-sonic frequencies, reduced the forces required to deform the metal, improved the surface finish and improved the metallurgical properties of the workpiece. There were, however, reports from other research workers which threw doubts on these claims and these gave rise to confusion from which only now is the science of oscillatory metal working emerging. Nevertheless, in spite of the confusion, one or two companies in the USA, principally specialising in the manufacture of ultrasonic equipment, carried out their own laboratory and works trials and subsequently marketed tube-drawing, dental-drilling, welding (both plastics and metals) and metalcutting units. Also, in the USSR several plants installed vibro-units, principally for low-frequency oscillatory forging, although tube-drawing apparatus was introduced into some works. This commercial exploitation proceeded in the absence of a clear understanding of the mechanics of oscillatory working; optimum processing conditions have not been established even now.