Laser cutting of materials of non-uniform thickness

The work conducted in this thesis addresses the problem of laser cutting of non-uniform thickness materials. This work addresses the problem of cutting of workpieces with small variations within certain limits of quality requirement. The objective of the work was extended to an intensive study of fibre laser cutting and striation formation during the laser cutting process, striation being the main source of surface roughness and inaccuracy. Where, striation free cut of variable thickness mild steel workpiece using single mode fibre laser was demonstrated and an understanding of striation formation during oxygen laser cutting of mild steel was given explaining striation formation for two reasons, side burning and molten material removal. Estimation for the minimum power required to achieve striation free cutting for different thickness mild steel was given. The role of recoil pressure, results from vaporization, on melt removal was discussed, as striation free cut can be achieved if the time required to remove the melt by the recoil pressure is less than or equal the interaction time.