Faster and damage-reduced laser cutting of thick ceramics using a simultaneous prescore approach

Laser machining of structural ceramics is increasingly gaining acceptance as an alternative to traditional machining methods. However, despite the great promise of lasers for a variety of cutting and drilling procedures, premature fractures and prohibitively low cutting speeds are still among the greatest obstacles encountered, particularly when thick cross sections are involved. While many factors contribute to the fractures encountered during laser machining, it is the inevitable and localized increase in temperature and the ensuing thermal stresses that usually cause the damage. As such, the minimization of heat buildup and the resulting thermal stresses often requires the slow and expensive practice of multiple pass or interrupted cutting or drilling. To help avoid the use of multiple-cut methods, while at the same time allowing for faster machining, a unique method of simultaneously scoring and cutting known as prescoring was explored using alumina plates. Using this technique and a design of experiment approach to systematically investigate the effects of various parameters, the use of prescoring was shown to significantly increase cutting rates for relatively thick alumina plates. In addition to improving cutting rates, the method was also shown to be capable of dictating the crack path when fracture could not be avoided.