Laser micromachining for mould manufacturing: I. The influence of operating parameters

Laser milling is a recent process in mould making, providing several advantages over traditional mould making technologies by reducing manufacturing time, shortening the number of machining operations and avoiding expensive electrodes. This paper investigates the influence of the operating conditions on both the surface quality and material removal for two types of materials commonly used in mould making.

Laser scanning strategies and operating parameters like scanning speed and laser frequency and power were tested, regarding surface quality and material removal rate. The most representative parameter of the real surface quality, R_k, the core roughness parameter, is used to characterise the surface finishing on all cavities.

The findings of this research work suggest that it is possible to significantly reduce processing time by increasing the hatch spacing up to a value close to the laser beam spot diameter, without compromising surface quality. Lower pulse frequencies and laser power are more appropriate whenever surface quality is an issue. Higher material removal rates are achieved by increasing both the pulse frequency till an optimum value and laser power. The increase of scanning speed reduces the material removal rate by decreasing the overlap degree between individual laser pulses.

The originality is to correlate the influence of the operating conditions of laser milling on both the surface quality and material removal for different types of materials.