Energy consumption and process characteristics of picosecond laser de-coating of cutting tools

Laser de-coating is a promising technology for selective coating removal to facilitate reuse of coated tools in a circular economy. It is timely to understand and optimise the quality, energy requirements and environmental footprint of the laser de-coating process. This paper reports on an investigation into process characteristics, energy demands and carbon footprints in coating removal from tungsten carbide tool inserts using high power picosecond laser sources with different pulse widths and wavelengths. The results demonstrate that although the 355 nm wavelength, 10 ps pulse width laser, has higher processing efficiency in terms of production rates, and lower specific energy for laser beam and material interaction, and results in better surface quality, the overall laser system energy consumption is much higher than that of using the 1064 nm wavelength, 150 ps pulse width laser for the removal of coatings on tungsten carbide cutting tools. This is largely due to the high energy demand of the water cooling system needed for the 355 nm wavelength picosecond laser whilst the 1064 nm picosecond is air cooled. There is therefore a need to optimise the total system energy consumption in the 355 nm picosecond laser, to support its superior laser de-coating performance. The paper shows the importance and challenges of optimising the energy consumption at different system boundaries.