The dynamics of laser surface modification

C Earl,J.R Castrejón-Pita,P.A Hilton,W O’Neill

doi:10.1016/j.jmapro.2015.10.002

C Earl, J.R Castrejón-Pita + Show 2 more

Open Access

https://doi.org/10.1016/j.jmapro.2015.10.002

Copy DOI

Abstract

The mechanisms involved in the production of surface features of protruding material formed by the interaction of a laser beam and a metallic substrate are investigated aiming to optimise the process efficiency. A relationship between laser induced surface features and filament breakup theory has been established. Results indicate that for the production of features the geometry of the protrusion with a filament critical aspect ratio over 6.0±1.0 is required. In addition results show the surface tension, viscosity and density of the molten material, and the dynamics of the process dictate the characteristics of the forming feature. Using filament breakup and spatter production equations surface feature processing parameters can be predicted as demonstrated by the three metallic materials used in this study: Aluminium 5000 series, Stainless steel 304 and Ti–6Al–4V, all of which show consistent results.

Highlights

Based on the results presented in this paper, it should be possible to predict the onset and processing parameters for laser surface feature production
It has been established that there is a strong relation between laser surface feature production and jet stability and breakup
Highspeed imaging has been used to show that filaments of molten material are produced due to the keyhole formation and dynamics

Summary

Introduction

Surface modification is of interest for potential applications to fields requiring an increased surface area; examples include material bonding and heat exchange. One such solution is Surfi-Sculpt® invented by TWI Ltd. [1], this surface modification technique uses repeated swipes of an electron or laser beam to produce surface features on material surfaces. The laser beam process variant involves translating a power beam source across the surface of the substrate in a manner similar to keyhole welding. This melts the material and causes the liquid to flow in the opposite direction to beam translation.

Methods

Results

Discussion

Conclusion