Browsing Faculty of Science and Engineering by Publisher "Oldcity Publications USA"
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Laser Cleaning of Grey Cast Iron Automotive Brake Disc: Rust Removal and Improvement in Surface IntegrityThere is a great need for removal of rust and surface damage from corroded engineering parts. This enables the retention of strength and increased longevity of metals and alloys in general. The use of lasers for cleaning, polishing and ablation has proven to be effective and promising overtime. This research is focused on a parametric study of laser cleaning a corroded grey cast iron brake disc. A continuous wave CO2 laser having a wavelength of 10.6μm was used for the study. A systematic approach was employed for the experiments where one parameter was changed while other parameters remained constant. Additional effects of laser cleaning were predicted by a Gaussian process regression approach. The results revealed that the best parameters which cleanly removed the rust were 60W of laser power, 900mm/s traverse speed, and a spot size of 722μm. The enhancement of surface microhardness of laser cleaned specimen was 37% compared to the rusted specimen surfaces. The roughness of the laser cleaned surface was, 1.29μm while the rusted surface comprised of 55.45μm (Ra). Microstructural analysis showed a presence of randomly distributed graphite flakes surrounded by a pearlitic matrix containing ferrite and cementite after laser cleaning. This was similar to that of the un-rusted surface. The hardness, roughness and microstructural content were in close relation with the respective properties of the unrusted automotive brake disc. This showed that the mechanical and physical properties of the brake disc were not altered negatively during the laser cleaning process. Implementation of the laser-cleaning technique in automotive and manufacturing industries should be embraced as it provides a faster, safer and cheaper way of enhancing the surface integrity of components and also paves way for other surface enhancement methodologies to be applied such as blast cleaning or laser shock cleaning for inducing extra strength, by beneficial residual stresses.