The effect of metal EOS 316L stainless steel additive manufacturing powder recycling on part characteristics and powder reusability

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 provide an insight to the effect that recycling AM powders has on the powder characteristics and on the quality of the parts produced

Prevalence of age-related macular degeneration in the Republic of Ireland

Abstract Background Age-related macular degeneration (AMD) remains the most common cause of visual loss among subjects over 50 years of age in the developed world. The Irish Longitudinal study on Ageing (TILDA) is a population-based study of subjects aged 50 years or older, designed to investigate factors that influence ageing, and has enabled this investigation of the prevalence of AMD in the Republic of Ireland (ROI). Methods Data collected from a nationally representative sample of community-living older adults aged 50 years and over in ROI over the period November 2009 to July 2011. 5035 participants attended the TILDA health centre for assessment. Retinal photographs were obtained in 4859 of these participants. Retinal grading was performed in a masked fashion using a modified version of the International Classification and Grading System for AMD. Results Adjusting for lower response rates among older subjects, the estimated overall prevalence of any AMD was 7.2% (95% CI 6.5% to 7.9%) in the population aged 50 years or older. The estimated prevalence of early AMD was 6.6% (95% CI 5.9% to 7.3%), and the estimated prevalence of late AMD was 0.6% (95% CI 0.4% to 0.8%). Statistically significant associations with AMD included increasing age and family history of the condition. Conclusions This is the first study to provide prevalence estimates of AMD in ROI and will inform eye care professionals and policymakers involved in the delivery and planning of care for those afflicted with this condition

Development of a Standalone In-Situ Monitoring System for Defect Detection in the Direct Metal Laser Sintering Process

Direct metal laser sintering (DMLS) is a powder bed fusion (PBF) additive manufacturing process commonly used within the medical device and aerospace industries where regulations drive the requirement for stringent quality control. Using in-situ monitoring, the identification of defects, as well as the geometric and dimensional measurement of the layers throughout the build allows for greater quality control, as well as a reduction in the requirement for ex-situ measurement. A standalone monitoring system for the EOS M280 is presented in this research, allowing for the build process to be monitored layer-by-layer. The system images the build area after powder deposition and after laser exposure allowing for the identification of inefficiencies in both the powder deposition and the laser exposure. The system has proven to be capable to identify in build defects and work is ongoing to develop an automated program to identify these defects and notify the operator in real time.Mechanical Engineerin

The value of open-source clinical science in pandemic response: lessons from ISARIC

International audienc