Scientific publication

Thermal modelling and experimental validation in the perspective of tool steel laser polishing
Written by Bastian Meylan, Alexandre Masserey, Eric Boillat, Ivan Calderon and

Outline

This contribution presents a thermal model based on the Chernoff formula for fixed and moving LP processes. The model was validated via a sensitivity analysis of the coefficient of absorption of the solid and liquid phase and through comparing the results with the corresponding experimental observations of the melt pools produced. In this investigation, a continuous wave, high power diode laser (980 nm wavelength, Ø 0.9 mm spot size with a flat top distribution) was coupled to a fixed focusing head. The material was a hardened tool steel (X38CrMVo5-1 steel-1.2343) with an initial surface state obtained by electrical discharge machining (EDM) of CH30 on the Charmilles scale for EDM, which corresponds to a roughness Ra of 3.15 µm. The results show that the model is able to represent the thermal behavior of the tool steel during LP. The best results are obtained with two constant coefficients, one for the solid based on the measurement at room temperature (a_s = 35%) and one for the liquid fixed so that the model fits the experiment data (a_l = 25%).

Reference

B. Meylan, A. Masserey, E. Boillat, I. Calderon and K. Wasmer, "Thermal modelling and experimental validation in the perspective of tool steel laser polishing". Appl. Sci. 2022, 12(17), 8409. DOI: https://doi.org/10.3390/app12178409

Supplementary data

Evolution of the melt pool during a static experiment, with a power of 317 W for a duration of 997 ms.

 

 

 

 

 

 

 

 

 

 

Evolution of the melt pool during a moving experiment (1^st line) with a sample velocity of 35 mm/s, a laser power of 415 W in the steady state regime.

Evolution of the melt pool during a moving experiment (2^nd line) with an overlap of the first line of 30%, a sample velocity of 35 mm/s, a laser power of 415 W in the steady state regime.