This study investigates the influence of mollusc-shell (MS) and squid-pen (SP) fillers on the tribological properties of high-density-polyethylene (HDPE) bio-composites (0, 5, 10, 15, and 20 wt. % of filler). Infrared analysis reveals that MS is primarily calcium carbonate, while SP is mainly chitin. MS addition significantly increased Rockwell hardness over unfilled HDPE. Friction coefficient for both fillers decreased up to a certain filler content. Specific wear rate increased with filler content for both bio-composites beyond 5 wt.%, suggesting agglomeration. Notably, 5 wt.% MS significantly reduced wear rate by 50% compared to unfilled HDPE. SEM images show that MS enhance wear morphology, creating finer scratches than unfilled HDPE and SP-HDPE. These findings show that MS improved HDPE bio-composites’ mechanical performance.
