Performance evaluation of recycled nylon polymer gears

This study investigates the performance of three different gears manufactured by injection moulding using: (i) virgin Nylon 6, (ii) a blend of 15% recycled Nylon 6 with virgin Nylon 6 (referred to as 15% RP material), and (iii) 15% RP material reinforced with 2% graphene oxide (GO). The compounding of materials was carried out using a twin-screw extruder, followed by gear fabrication through injection moulding. To evaluate the performance of the gears, tests such as wear analysis, surface roughness measurement, and temperature rise assessment of both the driving and driven gears were carried out under varying operating conditions. The experiments were performed at torque levels of 0, 4, 6, and 8 Nm, and rotational speeds of 800, 1000, and 1200 rpm. Among the three materials, the Graphene Oxide-reinforced composite exhibited superior performance, showing the lowest wear rate, reduced surface roughness, and better thermal stability across all torque and speed conditions. The improved behaviour of the GO-reinforced gear can be attributed to the uniform dispersion of GO nanosheets, which enhanced load-bearing capacity, interfacial bonding, and heat dissipation within the polymer matrix. In contrast, the pristine Nylon 6 gears displayed higher wear and surface roughness due to their limited thermal conductivity and susceptibility to surface deformation at elevated loads, while the 15% recycled Nylon 6 blend showed intermediate performance, maintaining acceptable tribological stability with moderate degradation. The incorporation of recycled content contributed positively to sustainability and circular economy goals, demonstrating that partial recycling does not critically compromise gear functionality.