Life-cycle energy and carbon saving potential of Wire Arc Additive Manufacturing for the repair of mold inserts

Additive Manufacturing (AM) has been identified as a disruptive technology, that enables the transition to Industry 4.0 and allows companies to re-think and re-design both their products and manufacturing approaches. In such a context, the opportunity of using AM to extend the life of a product through repair could also allow the founding principles of the circular economy to be implemented. This paper deals with the development of a repair procedure for mold inserts, made of H13 steel, that are used to cast aluminum cylinder heads for internal combustion engines. The repair operations were experimentally performed in a hybrid additive-subtractive manufacturing center used for Wire Arc Additive Manufacturing. Once the technological and quality results that are required by the strict industrial standards had been verified, the life-cycle energy and carbon footprint of the repair approach were quantified and compared with those of the conventional substitution-based approach. Overall, at the end of the first life of the insert, the results highlighted that the WAAM- and repair-based approach could allow potential savings for both performance metrics, compared with the insert being machined from a massive workpiece as a substitute, despite requiring several manufacturing steps and incoming feedstock material characterized by a high embodied energy. Moreover, the environmental benefits of the proposed approach are amplified when multiple repair loops are considered, even for a lower lifespan for the repaired mold insert.