No abstract

The demand for additive manufacturing (AM) of Cu and its alloys shows an increased trend from the energy and heat transfer related applications. Selective laser melting (SLM) is amongst the key AM processes for metals, providing high geometrical accuracy and design flexibility. The technology is most commonly employed using high brilliance fiber lasers operating at 1 m. However, the elevated reflectivity of Cu at this wavelength, combined with its high thermal conductivity is the cause for a highly unstable process, whereby pore-free products are difficult to obtain. Accordingly, the present work explores the limitations in processing pure Cu powders with a 1 kW single mode fiber laser providing solutions and different strategies for improving part quality. In particular, the power level requirements, as well as build plate material, is assessed through an analytical model. Later on, the process parameters were studied for single and multi-pass melting strategies.The results demonstrate that a correct sequence of multi-pass strategy can improve the part density up to 99.10.2% with an industrially acceptable build rate of 12.6 cm3/h.