Degree of particle melt in Nylon‐12 selective laser‐sintered parts

Purpose Selective laser‐sintered (SLS) parts are known to include un‐melted regions, where insufficient energy has been input into the powder to fully melt all particles. Previous research has shown the presence of two distinct peaks on a differential scanning calorimetry (DSC), and the purpose of this paper is to demonstrate that these peaks relate to the melted and un‐melted regions of the part. Design/methodology/approach SLS specimens were produced under different build parameters, in order to vary the amount of energy input, and DSC traces produced for each. DSC results were also compared with optical microscopy images to confirm the findings. Findings DSC analysis of SLS Nylon‐12 parts has shown the presence of two distinct melt peaks. It has been shown that these correspond to the melted and un‐melted regions of the part, and that the amount of energy input in the SLS process affects the degree of melting. It has also been identified, via correlation between DSC charts and optical microscopy images, that the un‐melted, or particle core, peak provides the most adequate indication of the proportion of melting. In order to avoid confusion with the commonly used term “degree of sintering”, which provides only a qualitative description, the new term “degree of particle melt (DPM)” has been defined in order to describe the quantitative variations in the completeness of sintering. Research limitations/implications Further work will correlate the DPM, as measured by the core peak height, with the mechanical properties of the parts produced. Practical implications Results have shown that it is possible to identify the level of melting in SLS parts via the use of a DSC chart. Owing to the small size of specimen required for DSC, and the relatively automated DSC procedure, this has the potential for use as quality control in SLS. Originality/value This is believed to be the first time that DSC has been used to indicate the DPM within SLS parts.