Laser surface modification of metal additive manufactured parts

Abstract

The demand for complex and personalized items made of a wide variety of materials is increasing day by day as people’s level of living rises. The limited ability of traditional manufacturing techniques to fabricate intricately structured objects in an efficient and cost-effective manner paved the way for further development of manufacturing processes like additive manufacturing (AM). AM process involves fabrication in a layer-by-layer addition of material to form parts with very complex geometry. The main drawback of additive manufactured products is their high surface roughness owing to the layered construction. Surface finish can be improved by polishing the component surfaces. Conventional polishing processes are not suitable for additive manufacturing products mainly because of the requirement for physical contact. Laser polishing operation, which is a contactless polishing process, can be advantageously applied in such cases. Laser polishing involves melting a thin layer of the substrate, with surface tension causing the material to flow from peaks to valleys. The molten metal is then allowed to re-solidify quickly, which ultimately leads to the generation of a smoother surface. The chapter focuses on different laser surface modification methods, theories, and mechanisms for metal additive manufactured parts. Toward the end, two experimental case studies are provided for in-situ and ex-situ laser polishing processes utilized for improving the part surface quality.