Study on process and parameter optimisation of selective laser sintering of thermoplastic polyurethane/carbon nanotube powder

Herein, the tensile strength of selective laser sintering thermoplastic polyurethane/carbon nanotube (TPU/CNT) composites was improved, and reasonable process parameters, addressing the delamination of TPU/CNT parts, smoke and other problems caused by materials' decomposition in the processing process, were determined. First, the TPU/CNT powder was processed by a single-factor experiment. The effects of laser power, scan spacing and layer thickness on the tensile strength were analysed, and the optimisation range of each process parameter was determined. The quadratic regression model of tensile strength was established based on Box-Behnken design scheme results, and its rationality was verified through analysis of variance. Finally, according to the target range of tensile strength, the selection conditions of each response value were determined, the process parameters were optimised and the measured data verified the predicted values. The test results show that the optimal combination of process parameters is 26 W laser power, 0.10 mm scan spacing and 0.10 mm layer thickness, and the relative error of the actual tensile strength of the optimised part compared with the predicted value is 0.096%. Compared with that before the optimisation, the tensile strength of the parts was increased by 4.42%. Besides, problems of parts' delamination and material decomposition causing smoke were solved.