Characterization and prediction of the heat-affected zone in a laser-assisted mechanical micromachining process

• Published in: International journal of machine tools & manufacture 2008-07, Vol.48 (9), p.994-1004
• Main Authors: Singh, Ramesh, Alberts, Matthew J., Melkote, Shreyes N.
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Heat-affected zone; Laser heating; Mechanical engineering. Machine design; Micromachining; Modeling; Precision engineering, watch making
• ISSN: 0890-6955; 1879-2170
• DOI: 10.1016/j.ijmachtools.2008.01.004

Laser-assisted mechanical micromachining (LAMM) is a micro-cutting method that employs highly localized thermal softening of the material by continuous wave laser irradiation focused in front of a miniature cutting tool. However, since it is a heat-assisted process, it can induce a detrimental heat-affected zone (HAZ) in the part. This paper focuses on characterization and prediction of the HAZ produced in a LAMM-based micro-grooving process. The heat-affected zone generated by laser heating of H-13 mold steel (42 HRC) at different laser scanning speeds is analyzed for changes in microstructure and microhardness. A 3-D transient finite element model for a moving Gaussian laser heat source is developed to predict the temperature distribution in the workpiece material. The model prediction error is found to be in the 5–15% range with most values falling within 10% of the measured temperatures. The predicted temperature distribution is correlated with the HAZ and a critical temperature range (840–890 °C) corresponding to the maximum depth of the HAZ is identified using a combination of metallography, hardness testing, and thermal modeling.