Currently, the majority of laser based additive manufacturing research uses a Gaussian laser beam profile, with some machines using a top-hat profile and recently, a ring intensity profile becoming more popular. The Gaussian profile results in a very high temperature at the centre of the melt pool, resulting in a deep melt pool and vaporisation of material. The advantages of a ring laser profile are said to be a wider processing window and a more stable melt pool, however, there is little understanding of how the beam shape affects the process. An attempt is made to validate the trends predicted by an analytical moving heat source simulation with those obtained experimentally to aid with designing new beam shapes. Many different laser beam profiles can be quickly tested, with melt pool dimensions, thermal gradient and solidification velocity calculated.

The simulation is purposefully minimal to allow for quick beam shape iteration; this sacrifices numerical accuracy, however, the trends in melt pool dimension should hold. For example, by optimising the cross-sectional melt pool shape, the hatch offset and layer thicknesses in the powder bed fusion process could be increased, improving process efficiency. Further, by carefully selecting a laser profile to specify thermal conditions (thermal gradient and solidification velocity), it may be possible to control the structure of the final component and to reduce defects such as hot-cracking. There are several laser companies researching/offering beam shaping, but before this is fully exploited, a fundamental understanding of the process is required.