Papers by Keyword: Laser Assisted Machining (LAM)

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Authors: Shou Jin Sun, Milan Brandt, John P.T. Mo
Abstract: A higher strength and heat resistance are increasingly demanded from the advanced engineering materials with high temperature applications in the aerospace industry. These properties make machining these materials very difficult because of the high cutting forces, cutting temperature and short tool life present. Laser assisted machining uses a laser beam to heat and soften the workpiece locally in front of the cutting tool. The temperature rise at the shear zone reduces the yield strength and work hardening of the workpiece, which make the plastic deformation of the hard-to-machine materials easier during machining. The state-of-the-art, benefits and challenges in laser assisted machining of metallic materials are summarized in this paper, and the improvement of tool life is discussed in relation to laser power, beam position and machining process parameters.
3359
Authors: Guenael Germain, Franck Morel, Jean Lu Lebrun, Anne Morel, Bertrand Huneau
Abstract: The use of Laser Assisted Machining (LAM) can improve different aspects of the machinability of high strength materials. A study was undertaken to determine the optimum cutting parameters and to quantify their influence on fatigue strength according to the type of microstructure created. Two different materials were studied: a bearing steel (100Cr6 / AISI 52100) and an aeronautical titanium alloy (Ti6Al4V). In the bearing steel a significant increase of the fatigue resistance was observed due to the transformation of the surface layer into martensite. For the titanium alloy, a slight reduction in the fatigue strength was found as in this case the microstructure and residual stress state of the surface layer was less beneficial. The surface roughness has also been measured and no significant variation has been observed for different laser powers in each material.
569
Authors: Xue Feng Wu, Hong Zhi Zhang, Yang Wang
Abstract: Laser assisted turning is an effective method machining difficult-to-machine materials such as ceramics, which uses a high power laser to focally heat a workpiece prior to material removal with a traditional cutting tool. A transient, three-dimensional heat transfer model was developed for laser assisted turning of silicon nitride using Finite Element Method to understand the thermal process of laser heating and to optimize the operating parameters. A laser assisted turning experiment system was set up to investigate the thermal conditions and cutting process of laser assisted turning of sintered silicon nitride and the experiments were conducted on the system using selected parameters. Effects of cutting parameters on cutting forces and specific cutting energy were investigated. Forces on the chip and SEM micrographs of chip morphology were studied to discuss the material removal mechanism of laser assisted turning of silicon nitride. Tool wear, surface roughness of the machined surface and the quality of subsurface were investigated. The results showed that the heat transfer model could be used to optimize the cutting parameters and laser assisted turning method could increase the machining efficiency while maintaining machining quality and reasonable levels of tool wear. A method of optimizing LAM based on the thermal model was presented.
113
Authors: Ji Hong Nancy Yang, Milan Brandt, Shou Jin Sun
Abstract: The aim of this work is to develop a 3-D transient finite element model for a moving Gaussian laser heat source to predict the depth of the heat-affected zone (HAZ) and temperature distribution in a Ti6Al4V alloy workpiece. It is found that the temperature profile and depth of HAZ are strongly dependent on the parameters of the laser beam. The thermal model simulations are compared with results produced by experimental work and these show close agreement.
143
Authors: Xue Feng Wu, Hong Zhi Zhang, Yang Wang, Chao Xie
Abstract: Laser assisted machining (LAM) is an effective method machining difficult-to-machine materials such as ceramics which uses a high power laser to focally heat a workpiece prior to material removal with a traditional cutting tool. A laser assisted machining experiment system was set up and a transient, three-dimensional heat transfer model was developed for LAM of silicon nitride using Finite Element Method to understand the thermal process of laser heating. The model was based on temperature-dependent thermophysical properties and the heat generated was neglected due to cutting which is assumed to be small compared to the heat generated by laser heating. The experiments were carried out to investigate the effects of operating parameters, such as laser power, laser translational speed, rotational speed, laser beam diameter and preheating time on temperature distribution. An infrared radiation thermometer was used to measure the surface temperature histories and the experimental results were in good agreement with predictions. The laser power and laser translational speed have the greatest influence on the temperature.
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