TWI Industrial Member Report Summary 269/1985
C J Dawes
Three different methods of laser beam spinning have been examined. A method whereby an angled optical flat is rotated below the focusing lens has been selected and an experimental apparatus developed. Welding trials have been conducted on 2 and 4mm HSLA steel butt joints to establish the advantages of laser beam spinning over conventional laser welding. The trials covered workpiece fitup, joint edge preparation and laser beam/workpiece joint misalignment. Using laser beam spinning, the tolerance to butt joint gaps was increased from 0.14 to 0.25mm (2mm material) for a total weld underfill of less than 15% sheet thickness.
Continuous and even welds with a total underfill of not more than 25% were achieved on specimens with guillotined edges butted in a 'V' form (4mm material), whereas the underfilling was irregular and up to 70% sheet thickness for the conventional laser welds. Using beam spinning the tolerance to laser beam/workpiece joint misalignment was increased from 0.25mm (conventional laser weld) to 0.5mm. However, with beam spinning the forward welding speed is reduced. The reduction has not been established practically, but is estimated to be ~20%.