Mechanics of Cone-on-Cone Friction on 3D-Printed Conical Surfaces Fabricated via Polymer Jetting

Understanding and controlling friction in additively manufactured surfaces is critical for optimizing component performance. For polymer-jet 3D-printed surfaces, the coupled effects of geometry, surface topology, and loading conditions on friction behaviors remain to a large underexplored. To quantify the frictional characteristics of 3D-printed surfaces, this study employs an integrated experimental and computational approach using custom-designed rotational tests on ring-on-ring (R-R) and cone-on-cone (C-C) geometries. The C-C type uses variable conical angles to investigate their effects on surface topology and the coefficient of friction (COF). Results reveal the COF exhibits a strong dependence on conical angles, with distinct frictional behaviors across configurations. The effects of normal force and angular velocity were also characterized, revealing pronounced stick-slip fluctuations at lower normal forces, especially for the 0° configuration. Surface topology, featuring circular and parallel patterns, was further analyzed through finite element (FE) simulations to quantify its influences on frictional response. The COF fluctuations persist for parallel patterns across all amplitudes but only manifest in circular patterns at larger amplitudes. While R-R assemblies exhibit lower mean shear stress yet lack optimal uniformity, C-C assemblies with small conical angles (2° and 5°) exhibit relatively uniform shear stress distribution. These findings advance the fundamental understanding of friction in polymer-jetted surfaces and support the design of tailored surface geometries for improved tribological performance in additive manufacturing.