Tailoring the Properties of Laser Sintered Composites for Tribological Applications

Laser Sintering enables the manufacturing of complex or bespoke, functional polymer components, yet controlling their tribological properties for subsequent applications still presents a challenge. This study explores the use of waste materials in low weight percent additions as functional additives into a nylon 12 Laser Sintered polymer. Here, the tribological performance of the nylon 12 composites is investigated under dry sliding conditions against a steel counterface, across two differing loads and two contact configurations, in accordance with ASTM G99.

Post sliding testing covered wear analysis and X-Ray Photoelectron Spectroscopy to identify wear rates and debris composition. The results demonstrate that contact condition exerts the greatest influence on tribological performance, probing fundamentally different friction and wear mechanisms. In the polymer disc configuration, unstable friction behaviour was observed, displaying repeated cycles of transfer film formation and disruption under the periodic contact. The polymer pin configuration prompted a more stable transfer film to form through continuous contact and improved debris retention on the counterface. Increasing the applied normal load reduced friction on the polymer disc but produced an opposite trend for the composite pins. This indicates that filler materials alter the load sensitivity of the tribological interface opposed to simply modifying the COF.

While surface roughness influenced the running-in behaviour, its effect diminished quickly after the first 50-70m of sliding. Under steady-state conditions, the tribological performance was governed predominantly by the transfer film evolution and third-body interactions. The composite containing waste carbon fibres exhibited the lowest COF and one of the lowest specific wear rates; while composites containing glass bead and calcium carbonate demonstrated significant reductions in friction despite negligible changes in surface morphology. These findings suggest that filler materials in low concentrations influence the tribological interface through modification of transfer film stability, providing insight into optimisation of Laser Sintered polymer components.