Modelling of powder catchment efficiency in micro-plasma transferred arc metal additive manufacturing process

This paper presents the development of a model of powder catchment efficiency of micro-plasma transferred arc metal additive manufacturing (µ-PTAMAM) process in terms of nozzle size, nozzle inclination angle, powder stream divergence angle, and stand-off-distance (SOD). It involved the development of models to evaluate powder concentration diameters in different zones of powder flow stream and melt pool. The developed theoretical model has been validated experimentally. Effects of SOD on surface defects in the manufactured product and deterioration of nozzle and gas lens of the deposition head have also been studied. It was observed that SOD has a negligible effect on the melt pool area implying that powder concentration area predominantly affects the powder catchment efficiency. It has been found that powder catchment efficiency is maximum when the base material is placed closer to the initial point of powder convergence which is 8–9 mm. Wastage of deposition material and surface defects in the manufactured product is reduced in this region. It also extends the life of deposition head components by reducing molten and spattered particle adhesion. The developed model will be useful to identify optimum SOD, minimizing wastage of the deposition material, maximizing powder catchment efficiency, and optimizing the design of the deposition head. This will lead to improvement in the techno-economical aspects of the µ-PTAMAM process.