Surface methods for monitoring the densification of parts in the selective laser sintering process

Abstract

Purpose – The purpose of this paper is to characterize polyamide parts prepared by the SLS process using techniques that are dependent on surface properties and compare the results to density measurements in order to assess which technique better reflects the degree of densification achieved using different laser power levels. Design/methodology/approach – Fabrication of Nylon 12 (Duraform PA) samples and their characterization by apparent density measurements, perfilometry, Raman spectroscopy, scanning electron microscopy, specific surface area and contact angle measurements. Findings – Methods dependent on surface analysis are not suitable indicators of the degree of sample densification. Among the surface methods, the results from Raman spectroscopy are the ones with the best performance. Incipient sintering of the superficial layers and raw material powder on the surface, inherent to the parts made by the SLS process, strongly interfere with the characterization. Originality/value – Quantitative comparison of a number of surface probing methods for monitoring densification of SLS parts. Characterization of sample surfaces with and without raw material powder.