Chapter 17 - Thermal Machining

Abstract

The two principal forms of thermal laser machining are scribing and drilling. They compete with athermal methods of laser machining when relatively large material removal rates are required, and dimensional tolerances on the order of micrometers are specified. Laser machining competes with conventional machining methods in applications involving rapid processing with simple fixturing and flexible geometries. By using an appropriate wavelength of laser light, all classes of engineering material may be machined irrespective of their physical and thermal properties. The copper vapor laser has gained a reputation for macromachining hard materials, producing cavities with a high aspect ratio (up to 30), because of its ability to produce high energy pulses with high repetition rates. Laser machining is also popular for processing hard ceramics, some of which are too brittle to machine using conventional methods, because ceramics absorb visible and ultraviolet light efficiently. Analytical modeling can be used to construct laser machining diagrams, which are applicable to both scribing and drilling. The models are simple enough to be modified to suit a variety of processing geometries, and are flexible enough to be applied to a range of engineering materials.