STUDY INTO THE EFFECT OF BEAM WAIST POSITION ON HOLE FORMATION IN THELASER DRILLING PROCESS

Laser drilling may improve by proper selection of the laser parameters . One of the important parameters in laser hole drilling is the focus setting of the focusing lens. In the present study, the effect of the beam waist position on the resulting hole exit/entry diameter ratio is investigated experimentally. An Nd-YAG laser is used to drill the hol es in stainless steel and mild steel sheers at different thicknesses. The study was conducted to include the physical processes involved at different beam waist positions during the drilling operations. It is s hown that altering the beam waist positions tends to produce convergin g and diverging hole walls for negative and positive positions respect ively. The drilling improves at a certain beam waist position for a gi ven workpiece thickness.