Surface finish improvement of LMD samples using laser polishing

Abstract

Laser metal deposition (LMD) is an additive manufacturing (AM) process used for repairing and fabricating metallic parts. One of the major drawbacks of this process is the relatively rough surface of the manufactured parts. In this work, surface polishing using laser for LMD parts was studied. Using the LMD process, a series of block samples of Inconel 718 were produced. The top surface of the samples was then laser scanned using combinations of parameters. The surface roughness of the samples was evaluated and subsequently, optimum process parameters set for laser polishing were predicted using analytical experimental design (DoE) software. The results showed the capability of a laser to improve the finishing surface of the LMD parts to about 2 µm Ra, which can be acceptable for many industrial applications. The relation of laser energy to final surface roughness was also studied, showing the strong dependency of surface finish on laser energy.

Keywords:

• surface roughness
• laser polishing
• laser metal deposition (LMD)
• design of experiments (DoE)
• laser energy

Acknowledgements

This work has been supported by an industrial collaborative research project entitled ‘Added Value by Laser Assisted Additive Manufacture – AVLAM’. AVLAM project is a collaboration between the TWI Ltd, University of Exeter, EADS UK, Bombardier Aerospace plc, TISICS Ltd and Manterialise UK. The Project is managed by TWI Ltd and is partly funded by the TSB under the Technology Programme ref: ‘AB183A’.