No abstract

Direct metal laser sintering (DMLS) is a powder bed fusion (PBF) process commonly used within the medical device and aerospace industries to fabricate high value, complex components. Powder material used in the DMLS process can be costly and it is rare for a single build to require a full batch of powder. The un-melted powder, which differs in particle size and morphology from virgin powder, is often recycled for further builds. This work presents a study of the effects that recycling a stainless steel metal powder used in the DMLS process has on finished parts. Hence in this paper, powder material characteristics, such as particle size, particle morphology and bulk chemical composition have been monitored throughout the recycling process. An analysis of parts manufactured via DMLS on an EOS M280 demonstrate the negative effect of powder recycling on part quality in terms of surface roughness, part density, hardness and dimensional accuracy. Results from this research provides an insight to the effect that recycling AM powders has on the powder characteristics and on the quality of the parts produced.

Metal additive manufacturing (AM) processes, viz laser powder bed fusion (L-PBF), are becoming an increasingly popular manufacturing tool for a range of industries. The powder material used in L-PBF is costly, and it is rare for a single batch of powder to be used in a single L-PBF build. The un-melted powder material can be sieved and recycled for further builds, significantly increasing its utilisation. Previous studies conducted by the authors have tracked the effect of both powder recycling and powder rejuvenation processes on the powder characteristics and L-PBF part properties. This paper investigates the use of multiple linear regression to build empirical models to predict the part density and surface roughness of 316L stainless steel parts manufactured using recycled and rejuvenated powder based on the powder characteristics. The developed models built on the understanding of the effect of powder characteristics on the part properties. The developed models were found to be capable of predicting the part density and surface roughness to within ±0.02% and ±0.5 Ra, respectively. The models developed enable L-PBF operators to input powder characteristics and predict the expected part density and surface roughness.

Publication informationTechnology Analysis and Strategic Management, 21 (5)

Fiona Whelan and Jim Lawlor, based in Dublin Ireland, have been working together since 2004; Jim as Manager of Rialto Youth Project, a community-based youth service in Dublin’s south inner city; and Fiona as artist-in-residence there. Together, and in collaboration with a range of other partners in youth work, community development, the arts and beyond, their collaborative practice has been committed to a complex critical exploration of power relations at a personal, community and societal levels. In this conversation, they exchange and build analyses of prior arts processes that engaged young people and adults in open-ended dialogical enquiries into power and inequality. They also critically interrogate the values and methodologies at the core of those collaborations. As contemporary youth work and community development in Ireland becomes increasingly evidence-based and outcome-driven, Fiona and Jim debate and argue for an emergent approach to practice that is collaborative, open-ended, dialogical, and imaginative.