Air-cooling influence on wire arc additive manufactured surfaces

WAAM (Wire-Arc-Additive-Manufacturing) is an additive manufacturing process which uses arc welding to produce metal parts. This process is prone to the detrimental phenomenon of heat accumulation, i.e. a progressive increase of the interlayer temperature. This paper investigates the effect of air jet impingement cooling in mitigating heat accumulation, considering both workpiece temperature and surface geometry. Test cases were manufactured using free convection cooling and air jet impingement. The workpiece temperature was measured by K-type thermocouples and the surface waviness by a coordinate measuring machine. The results were compared in terms of deposition efficiency, deposit height and average arithmetical deviation. The temperature results highlight that air jet impingement is effective in preventing the occurrence of heat accumulation. The surface data highlighted that air jet impingement caused an increase of the deposited wall height between 0.5 mm and 2.0 mm and a decrease of the deposition efficiency up to 10%, caused by a higher surface waviness.