3.1 Laser power
A high power laser is used to melt metal powder supplied coaxially to the focus of the laser beam through a deposition head.The energy poured into the melt pool gradually rises along with the laser beam’s intensity. The laser power is the rate at which energy is emitted from the laser beam. The laser is primarily used in the LENS process to liquefy metallic powder to form a melt-pool, which solidifies upon cooling to form the build voxel of a respective layer. Laser power is possibly the most important process parameter in LENS, with variations in this parameter having the greatest impact on the mechanical properties of a part. When a dense structure is required, for example, the laser power can be increased to avoid partial melting zones (porous structures), but this can also result in undesirable microstructural changes. In some cases, increasing laser power causes grain size to increase, lowering hardness and potentially affecting other mechanical properties.Not only does laser power affect mechanical properties; according to Mahamood and Akinlabi analysis, surface roughness decreased linearly with increasing laser power, improving surface finish.