Abstract
Diode area melting (DAM) is a new additive manufacturing process that utilises customised architectural arrays of low-power laser diode emitters for high-speed parallel processing of metallic feedstock. The laser diodes operate at shorter laser wavelengths (808 nm) than conventional SLM fibre lasers (1064 nm) theoretically enabling more efficient energy absorption for specific materials. This investigation presents the first work investigating the melt pool properties and thermal effects of the multi-laser DAM process, modelling generated melt pools the unique thermal profiles created along a powder bed during processing. Using this approach process, optimisation can be improved by analysing this thermal temperature distribution, targeting processing conditions that induce full melting for variable powder layer thicknesses. In this work, the developed thermal model simulates the DAM processing of 316L stainless steel and is validated with experimental trials. The simulation indicates that multi-laser DAM methodology can reduce residual stress formation compared to the single point laser scanning methods used during selective laser melting.
Highlights
Additive manufacturing (AM) technologies are capable of creating geometrically efficient structures with low material wastage
The model was capable of predicting temperature evolution through the powder layer to the solid substrate, modelling the Diode area melting (DAM) limitation of inter-layer melt disruption reported in literature for processing multi-layer 316L stainless steel components
It was observed that the DAM methodology can effectively reduce temperature gradient and cooling rates, theoretically reducing residual stress build-up due to its characteristic melting mechanism composed of multiple parallel scanning vectors with low individual power and low scan speeds
Summary
Additive manufacturing (AM) technologies are capable of creating geometrically efficient structures with low material wastage. The melting source (deflected laser/ electron beam) selectively scans and melts regions of a predeposited powder bed. Cross sections of the part are fused in layers, built up successively to create the complete 3D object. This method of layered fabrication, combined with the high precision of laser melting, allows for a greatly expanded design freedom with minimal feedstock waste. Diode area melting (DAM) is a novel powder-bed-based AM process for the manufacture of metallic components with ability to process materials with melt temperatures in excess of 1400 °C [1] using a multi-spot array of low powered laser beams.
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