Preparation and selective laser sintering of nylon-coated metal powders for the indirect SLS process

Purpose - The purpose of this paper is to report a new method, the dissolution-precipitation process, to prepare nylon-coated metal powders for the indirect selective laser sintering (SLS) process. Design/methodology/approach - The nylon-12 coated carbon steel powders were prepared by the dissolution-precipitation process. The powder characteristics are examined by scanning electron microscope (SEM) and laser diffraction particle size analysis. The effect of the applied laser energy density on the three-point bend strength and dimensional accuracy of the SLS specimens are studied. The influence of nylon-12 content on the bend strength are also investigated. Findings - The SEM and laser diffraction particle size analysis results indicate that the steel particles are well coated by nylon-12 resin. The bend strength of the SLS specimens increases with increasing the applied energy density until it reaches a maximum value, and then further increasing energy density will cause the decrease in the bend strength. The bend strength of the SLS specimens increases with increasing the nylon-12 content over the investigated range. The dimensional errors in the X-Y-and Z-directions are all increased with the increase in energy density. Research limitations/implications - This paper only concerns the preparation and SLS of the coated powders. Further investigations are planned into post-processing, such as binder decomposition and high-temperature sintering, of the green parts made from the coated powders. Originality/value - This paper provides a useful method for preparing nylon-coated metal powders for making metal parts by the indirect SLS process.