Experimental analysis of axial and torsional vibrations assisted tapping of titanium alloy

Abstract

Sudden breakage of a tap is frequently encountered during tapping small diameter internal threads on titanium alloys. This work therefore presents an extensive experimentation to investigate mechanism and performance of tapping in titanium alloys in the presence of axial and, axial and torsional vibration-assisted tapping (AVAT and ATVAT). Tapping cycles based on the variation in thrust and torque in tapping have been established, which illustrate subtle differences in the tapping phenomena as a consequence of vibrations. AVAT and ATVAT were found to reduce tapping torque, axial force and temperature over that of the conventional tapping (CT) without compromising the thread quality. Between ATVAT and AVAT, ATVAT gives improved performance. The ATVAT and AVAT processes generate elastic recovery-free superior surfaces as against the heavily recovered surfaces in CT. Microstructure of the tapped surfaces shows a reduction in tapping affected zone in ATVAT and AVAT than that of in CT.