Using wire shaping techniques and holographic optics to optimize deposition characteristics in wire-based laser cladding

Abstract

In laser cladding, the potential benefits of wire feeding are considerable. Typical problems with the use of powder, such as gas entrapment, sub-100% material density and low deposition rate are all avoided with the use of wire. However, the use of a powder-based source material is the industry standard, with wire-based deposition generally regarded as an academic curiosity. This is because, although wire-based methods have been shown to be capable of superior quality results, the wire-based process is more difficult to control. In this work, the potential for wire shaping techniques, combined with existing holographic optical element knowledge, is investigated in order to further improve the processing characteristics. Experiments with pre-placed wire showed the ability of shaped wire to provide uniformity of wire melting compared with standard round wire, giving reduced power density requirements and superior control of clad track dilution. When feeding with flat wire, the resulting clad tracks showed a greater level of quality consistency and became less sensitive to alterations in processing conditions. In addition, a 22% increase in deposition rate was achieved. Stacking of multiple layers demonstrated the ability to create fully dense, three-dimensional structures, with directional metallurgical grain growth and uniform chemical structure.

Industrial Energy Optimisation: A Laser Cutting Case Study

“…The use of preheated wires to reduce energy consumption in laser welding achieved energy reductions of 16% [6]. Other experiments have investigated wire shaping in laser Directed Energy Deposition (DED) by Goffin et al [7], and laser beam shaping by Wellburn et al [8] and Mok et al [9]. There have also been many system-level investigations of different laser processes.…”

Mathematical modelling for energy efficiency improvement in laser welding

“…In wire-fed laser cladding, many industrial examples exist of pre-heated wire feeders, and academic work has shown the ability for this to reduce laser energy consumption by up to 16% (Wei et al, 2015). Other work experimented with altering the shape of the wire to optimise absorption, which gave a 22% productivity improvement in laser cladding (Goffin et al, 2016), (Goffin et al, 2014). The use of custom laser beam profiles for annealing thermal treatments of thin-film photovoltaics has also demonstrated the ability to initiate grain growth as a replacement for conventional annealing (Liscoet al, 2017).…”

“…Material density was 0.008 kg/cm 3 , used to calculate process productivity in terms of mass. As with previous work by Goffin et al (2016), coupons were created to thermally isolate individual weld tracks. Post-welding, samples were sectioned, polished, and etched with Kalling's #2 reagent to reveal weld microstructure for measurements.…”

Just how (in)efficient is my laser system? Identifying opportunities for theoretical and auxiliary energy optimization

“…The welding substrate was stainless steel 316L sheet, 0.8 mm thick. As with previous work by Goffin et al [17], coupons were created to thermally isolate individual weld tracks. The gaps between each coupon were designed to prevent the heat from one weld run from affecting adjacent tracks.…”