Comparative costs of additive manufacturing vs. machining: The case study of the production of forming dies for tube bending

Additive manufacturing processes for metallic components become economically viable when they substitute conventional processes that make use of moulds and dies to produce casting or semi-finished parts with high added value. Common examples are: i) components in aerospace or energy sectors obtained by investment casting in high-temperature alloys; ii) personalized prostheses and implants in biocompatible metals in the biomedical sector. In both cases, the annual batch size is low and often limited to a single or few pieces. However, for many other sectors decision making for process substitution from conventional to AM processes requires a correct economic analysis. The cost of AM processes depends also on the use of technological advantages. The paper explores the economic feasibility of selective laser melting (SLM) process when producing tube-forming tools. The analysed industrial case addresses the whole annual production of bending tools, traditionally made by milling from a solid block. The aim of this work is to identify the levers of the process that make additive production advantageous, even in more traditional sectors like tooling when different tool materials are used (namely a tool steel and a bronze alloy) and when hybrid manufacturing (subtractive plus additive) is carried out.