Design-for-service decision in additive manufacturing part consolidation linking service life, spare-parts demand, production, and life-cycle burdens

Additive manufacturing (AM) part consolidation is first a redesign decision and then a manufacturing decision. In spare-parts support for production systems, redesign changes degradation-limited service life; service life changes planned and corrective replacement demand; and replacement demand affects production, maintenance, inventory, energy demand, and emissions. This study develops a renewal-based decision-aid framework for AM part consolidation that links design choices with service life, replacement demand, and five system indices: production burden, maintenance burden, inventory burden, cumulative energy demand, and global warming potential. The framework is applied to a 316L bracket comparing welded conventional manufacturing, AM consolidation, and AM with topology optimisation across service classes, stress states, quality archetypes, replenishment conditions, and electricity-emission contexts. Results show that AM consolidation is not intrinsically preferable. AM creates system-level value only when service-life improvement offsets additional production, stockholding, and environmental burdens. Inventory can remain the binding constraint despite production or environmental gains, and topology optimisation can reverse AM benefits when stress concentration shortens fatigue life. The contribution is a product-to-service-demand mechanism that makes spare-part demand endogenous to redesign and identifies which production, maintenance, inventory, energy, or emissions bottleneck must change before AM adoption becomes favourable.