The effect of material thickness, laser power and cutting speed on cut path deviation in high-power diode laser chip-free cutting of glass

In the laser cleaving of brittle materials, using controlled fracture technique, thermal stresses are used to induce the crack and the material is separated along the cutting path by extending the crack. One of the problems in laser cutting of glass with this technique is the cut path deviation at the leading and the trailing edges of the glass sheet. Previous work has shown this deviation to be partly due to the high magnitudes of thermal stresses generated near the edges of the sheet. This paper reports on the experimental results of the effects of glass thickness, laser power and the cutting speed on cut path deviation in diode laser cutting of glass. Finite element modelling of the cutting process has also been used to simulate the transient effects of the moving beam and predict thermal fields and stress distributions. These predictions are validated against the experimental data and are used to explain the process mechanisms. It is shown that an increase in the thickness of the glass sheet for the same power and cutting speed or an increase in the cutting speed with constant power and a given sheet thickness results in smaller cut path deviations at the leading and trailing edges of the glass sheet.