Surface texturing, residual stresses and edge treatment of hardmetal tools by means of femtosecond pulsed laser

Abstract

Laser induced periodic surface structures (LIPSS) have been produced at the surface of a WC-Co turning insert by femtosecond pulsed laser ablation. Wavelengths of approx. 500 nm have been obtained with a 1030 nm incident radiation and with a spot size of 30 μm. No thermal damage is induced by following this procedure, although a slight surface stress relaxation is detected as fluence increases. The higher material removal needed for chamfering operations requires accumulated fluences over 1 kJ/cm2. At lower energy densities, material removal is not completed. If fluence is increased by reducing the laser spot size, material removal is also inefficient since signicant amount of debris is accumulated on the irradiated areas. Best chamfering strategy involves the combination of relatively large spot sizes and fluences. Form factors (Κappa) of the chamfered cutting edges range from 4 to 10 although the laser is oriented at 45° of the rake face. Lower Κ values can be obtained by adjusting the laser focus along the machining process.