The Effects of Virgin and Recycled PA12 Powders in SLS Processes on Occupational Exposures

Amir Abdullah Muhamad Damanhuri,Azian Hariri,Nuur Azreen Paiman,Safarudin Ghazali Herawan,Mohd Syafiq Syazwan Mustafa,Sharin Ab Ghani

doi:10.18178/ijesd.2021.12.11.1359

Amir Abdullah Muhamad Damanhuri, Azian Hariri + Show 4 more

Open Access

https://doi.org/10.18178/ijesd.2021.12.11.1359

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Abstract

Particulate matter and ultrafine particles are emitted during the pre-processing and post-processing activities of selective laser sintering (SLS) processes, which is major concern to operators exposed to the powders. This study aims to determine the occupational exposure (in terms of the total particle concentration and respirable particulate concentration) during the pre-processing and post-processing activities of SLS processes using virgin and recycled polyamide 12 (PA12) powders. Personal air sampling was performed for each activity according to the NIOSH 0500 and NIOSH 0600 methods. Based on the results, both powders were uniform spheres with a particle size of 40–60 μm. The total particulate concentration was most significant during the following pre-processing activities: 1) pouring powder into the mixing machine and 2) transferring the powder to the SLS AM machine. The total particulate concentration and respirable particulate concentration were slightly higher for the virgin powder for these activities. In conclusion, the virgin and recycled PA12 powders were both inhalable and respirable, which poses serious health hazards to the SLS AM operators. Hence, it is essential for operators to use suitable personal protective equipment (including respirators) and the working practices need to be improved by automating

Highlights

Additive manufacturing (AM) has been widely used in various industrial sectors such as aviation, biomedicine, automotive, and construction
The results indicate that respirable particulates constitute a major portion of the particulates when recycled PA12 powder is used for SLS processes, since the time-weighted average (TWA) total particulate concentration does not differ significantly from the TWA respirable particulate concentration
The scanning electron microscopy (SEM) images revealed that the PA12 powder particles were uniform spheres; the presence of voids was more apparent for the recycled powder

Summary

Introduction

Additive manufacturing (AM) has been widely used in various industrial sectors such as aviation, biomedicine, automotive, and construction. With AM, manufacturers are able to realize complex three-dimensional (3D) objects based on the models drawn using a computer aided design (CAD) software. In AM, the object, product, or prototype is created by joining materials layer by layer at a time [2], unlike subtractive manufacturing, where the material is cut (subtracted) from the block of material by grinding, rubbing, or drilling [3]. One of the advantages of AM is that it can significantly boost time savings by 50% in building prototypes. Another advantage of AM is its flexibility, where businesses can modify the prototypes and customize products to cater to different customers [4]

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