Investigating the compression properties of selective laser sintered Nylon-12

The Selective Laser Sintering (SLS) process is a widely established Rapid Manufacturing technology that offers various possibilities not available from other production techniques. The application of SLS in the creation of products such as shoe outsoles has led to a requirement for compression property data and an understanding of the factors that influence it. This research investigated the effect of sintering temperature on the compression modulus and strength of SLS nylon-12 parts. Three parameters were used to vary the sintering temperature. These were laser power, part heater set point and powder bed location. An increase in laser power or part heater set point led to an increase sintering temperature. The higher temperature areas within the powder bed also led to higher sintering temperatures. Consequently, this caused an increase in compression properties. A statistical analysis showed that laser power and part heater set point had a statistically significant effect on compression properties. They both had over a 95% probability of influencing compression properties. With less than a 95% chance, the effect of bed location on compression properties was considered statistically insignificant. The variations in temperature also led to changes in crystallinity and density. An increase in temperature caused a decrease in crystallinity. In contrast density was increased as temperature increased. Except for parts built at various bed locations, there was over a 95% certainty that temperature caused differences in crystallinity and density. However, there was a less than 95% probability that crystallinity and density influenced compression properties. Hence, they had no statistically significant effect on compression modulus and strength. This work has added to the knowledge base of SLS nylon-12 within the specified boundaries of this research. Users of this technology who consider compression modulus and strength to be of importance can focus their efforts on optimising sintering temperature. This has been shown to have a greater statistical impact on compression properties compared to crystallinity and density.