Air Jet Cooling Applied to Wire Arc Additive Manufacturing: A Hybrid Numerical-Experimental Investigation

WAAM (Wire Arc Additive Manufacturing) is a metal additive manufacturing process based on gas metal arc welding which enables to create large parts with a high deposition rate. WAAM is prone to the heat accumulation issue, i.e. a progressive increase of the workpiece internal energy due to the high heat input of the welding process, which can cause defects such as part structural collapse, uneven layers geometry or non-homogenous microstructure. A promising technique to mitigate such issue is to use an air jet impinging on the deposited material to increase the convective heat transfer. This paper presents an analysis of air jet impingement performances by means of a hybrid numerical-experimental approach. Different samples of a test case are manufactured using free convection cooling, air jet impingement and different interlayer idle times. Substrate temperatures are measured and compared with the results of a finite element simulation to assess its accuracy. The performances of air jet impingement are analyzed in terms of measured substrate temperatures and of simulated interlayer temperature, evaluated at the top of each layer. The results highlight that air jet impingement has a significant impact on the process, limiting the progressive increase of interlayer temperature compared with free convection cooling.