The analysis of CO₂ laser cutting

The laser finds increasing commercial use as a cutting tool. The laser cutting quality characteristics require microscopic evaluation of the resulting cut properties. Striation is considered as one of the important quality characteristics and its formation is strongly related to cutting and workpiece parameters. However, the mechanism of formation of striations has not yet been well established. To enhance the understanding of striation and its properties, the present study is conducted. A mathematical model relevant to formation of striation is developed, and striation width and frequency are predicted. In the model a heat transfer equation employing a moving heat source and allowing a chemical reaction contribution to available power at the workpiece surface, due to an assisting gas effect, is introduced. The study is extended to include experimental investigation into the striation process. Consequently, striation frequency and striation width are measured using the microphotography technique and a fibre-optic probe. It is found that the mathematical model introduced represents the physical phenomena well, with the limits of characteristic distance, striation frequency and striation width, as predicted, agreeing well with the experimental findings.