Influence of surface characteristics on fatigue behaviour of laser sintered plastics

Purpose - The purpose of this paper is to provide macromechanical insight into the fatigue behaviour of laser sintered parts and to understand the influence of the laser sintered surface structure on this behaviour. Design/methodology/approach - A background on the technological maturity of manufacturing processes and the demand for structural and aesthetic properties of laser sintered plastic products is given. As the contribution of surface structure on part quality was the focus, laser sintered specimens with and without surface finishes, as well as injection moulded specimens were used. The latter simply served as a comparison and was not intended to qualify injection moulding. The study comprises the determination of short-term tensile properties, the load increase method for investigating fracture and deformation behaviours, and fatigue crack propagation analysis. Findings - According to the test results, the contribution of laser sintered surface structures to relevant mechanical properties can be neglected. Under dynamic loading conditions, laser sintered specimens achieved a longer lifetime but showed less deformation capabilities in contrast to injection moulded specimens. In general, laser sintered specimens presented considerable resistance to crack initiation and propagation. Research limitations/implications - Because of the long-term approach of the research, the number of tests conducted per lot was limited. Thus, the effects of different process settings and the reproducibility could not be fully analysed. Practical implications - The studied fatigue behaviour of laser sintered specimens has implications for the functional testing of parts or components, for the product and process design as well as for the general compatibility of laser sintering as a manufacturing technology of end-customer products. Originality/value - The value of this paper lies in the better understanding of deformation and fracture behaviours of laser sintered polymers.