Laser cutting of thick steel plate

Of the many machining processes used in manufacturing to cut metals and non-metals, laser cutting offers unique advantages in terms of cut quality, speed, absence of tool wear and minimal or no clamping of parts. In industry, the lasers used for cutting are CO2 (carbon dioxide) and Nd:YAG (Neodymium-doped Yttrium Aluminium Garnet) lasers each with their own characteristic output properties such as wavelength, power) mode of operation and beam quality. These properties, together with the optical and thermophysical properties of workpiece material and workpiece handling system, control and determine the cutting performance of any material. Presented in this paper are laser, materials and system properties, and parameters influencing the cutting of metals in particular. The operation of the CO2 and Nd:YAG lasers and their dominant features is also discussed. The cutting mechanism is described in terms of the energy balance within the workpiece. This is then used to show the difficulties with cutting thick (>10mm) steel plate with a laser, leading into a number of novel laser methods explored for the cutting of thick plates. Finally, recent work supported by the CRC for Intelligent Manufacturing Systems and Technologies (CRCIMST) on laser cutting with a 'spinning laser beam' is presented and its potential for cutting thick steel plate discussed.