Modelling the laser fusion cutting process: I. Mathematical modellingof the cut kerf geometry for laser fusion cutting of thick metal

Abstract

A model for calculating the three-dimensional stationary geometricshape of the cutting front for laser fusion cutting is presented in thispaper. The model relates the cut kerf geometry with the cut-through depth,various laser parameters such as power, speed, focus position and materialthickness. In this model, the energy absorbed by the workpiece includes notonly the direct energy from the laser beam but also the energy from themultiple reflections generated by the beam impinging on the cutting front ofthe cut kerf. The effects of multiple reflections are functions of theinclined angle of the cutting front and the cutting depth. The effects ofvarious laser processing parameters, multiple reflections and inert gaspressure on the geometric shape of the cutting front have been analysedsystematically and in detail. The model allows accurate prediction of thecut-through depth and cut-edge quality for a given set of process parameters.It also helps to explain the effect of focal position, cut-assist pressure andother parameters upon the cut-edge quality.