As part of the international “Ad-Proc-Add” of the ecoplus Mechatronics Cluster, Belgian researchers from KU Leuven, Thomas More University, the Belgian Welding Institute, and Sirrishave investigated the influence of various processes within the additive-subtractive manufacturing process chain (ASM) on the quality of the end product and developed empirical models for predicting bead geometry for the conventional Gas Metal Arc Welding (GMAW) process and the Cold Metal Transfer (CMT) process.

Wire and Arc Additive Manufacturing (WAAM) is an additive manufacturing technique that uses an electric arc as a fusion source to melt filler wire and build a component layer by layer. WAAM enables efficient production of medium to large metal parts, but after deposition, it exhibits low dimensional accuracy and surface quality, which is why further subtractive post-processing is usually required.

A key aspect of the project was determining the material to be provided for machining in order to achieve the required dimensional and shape accuracy of the part. It was found that the WAAM process parameters have a significant influence on the effective wall width, the surface quality after deposition, and the minimum amount of material that needs to be removed during the post-processing step.

Another important finding related to the positioning, orientation, and optimal cutting parameters of the parts for post-processing. Experiments showed that the WAAM process parameters, especially speed, wire feed, and interpass temperature, have a significant influence on the characteristics of the deposited surface and the overall wall width that influence the milling process.

Significant progress was made through the development of multi-sensor platforms, which were used separately for the AM and post-processing steps, to investigate the influence of different processes on the properties of the final part. By monitoring current, voltage, gas flow rate, and temperature, the stability of the WAAM process could be evaluated, thereby eliminating various material defects and improving surface performance.

The insights gained were applied to various industrial case study parts. Research on GMAW-based WAAM and the ASM process chain is now part of several educational courses at KU Leuven and Thomas More. These advances demonstrate the enormous potential of WAAM technology and how it can be used to improve efficiency and quality in additive manufacturing.

Further information is available on the project website: www.ad-proc-add.eu