Effects of Fibre Laser Beam Focal Point Location and Incidence Angle on the Cut Quality of Stainless Steel Sheet

Fibre lasers, owing to their higher efficiency, better beam quality and robust design, offer distinct advantages over more established laser systems in sheet metal cutting applications. But, high focussability and shorter wavelength of this laser is found to be advantageous for cutting thin sheets only. Fibre laser is reported to have an unfavourable incidence angle in cutting thick sections, resulting in poor absorption; moreover, the narrow kerf produced by fibre laser causes an earlier flow separation of assist gas inside kerf, resulting in poor cut. So, the effect of focal point position and incidence angle on cut quality of 4.00 mm thick AISI 304 stainless steel sheets has been investigated. Shift of focal point location towards the bottom surface was found to produce wider kerf, resulting in improved cut quality. The change in laser incidence angle also improved the cut quality. Results of the detailed parametric study are presented.