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Child labour is a worldwide phenomenon but more focus is required on developing countries. The policy framework of International Labour Organization (ILO) to eliminate child labour is based on United Nations (UN) Declaration of Fundamental Principles and Rights at work (1998)

Polyamide, with its low friction coefficient, high heat resistance and good moldability, is a promising polymer to meet the rising demand for lightweight, durable gears. This paper considered injection-molded polyamide 66-polyamide 66 gear pair wear performance under unlubricated and wet lubricated condition. The experiment was conducted using in-house developed power absorption gear test rig. The torque of 1.8 Nm, rotational speed 800 rev/s and lubricant SAE 75W85 was considered during testing. During the test, gear tooth temperature under unlubricated condition and lubricant temperature under wet lubricant condition was measured and monitored. The net surface temperature on the gear surface and lubricant was observed as 370 K and 303.4 K, respectively. The transmission efficiency was increased by 5% compared to the unlubricated condition. Testing confirmed that the gear exhibited surface wear at both the face and flank region in unlubricated condition. While testing under wet lubricant condition, the wear was observed on the face of the gear. Simulation result confirmed that the deflection of test gear is significantly higher in double tooth contact region shared by the face side as compared to flank side of the driven (test) gear. That could be the possible reason for test tooth wear in the face region.

Purpose This paper aims to understand the effect of the manufacturing process on the frictional and wear performance of polyamide. Design/methodology/approach Pin specimens were manufactured through injection moulding (IM) and selective laser sintering (SLS) manufacturing processes. The friction and wear performance was evaluated using a pin-on-disc configuration under dry and oil-lubricated conditions. The friction coefficient, wear resistance and surface temperature of specimens were measured, and failure morphology analysis was carried out to understand the mechanism. Findings SLS material exhibited significantly less friction, wear and surface temperature than IM material under dry conditions. Reduced ductility due to the sintering contributes to reduced friction, wear and heat generation. Under the dry condition, IM material exhibited plastic flow and roll-shaped deformation, whereas SLS material exhibited only local degradation due to its lesser ductility. Lubrication reduced friction and temperature for both SLS and IM materials. The porous nature of the sintered surface absorbed the lubricant and released it while sliding, which is confirmed by the brown-coloured wear track. Originality/value The study provides valuable input to the designers on the sliding contact performance of commonly adopted two different manufacturing processes of polymers; IM and SLS manufacturing.

The fatigue and tribological performance of thermoplastic-based gears have been investigated extensively so far, but no such work has been done on elastomeric gears. In the current work, the feasibility of utilizing elastomeric material for gear applications was investigated. Initially, the sliding contact performance of an elastomeric material under dry and oil-lubricated conditions was examined. Subsequently, the elastomeric gears were subjected to bending and contact loads under dry and oil-lubricated conditions. The elastomeric gear exhibited only tooth root cracks owing to bending fatigue under both dry and oil-lubricated conditions. Unlike thermoplastic-based gears, elastomeric gears do not exhibit thermal deformation or wear failures. The presence of voids in the elastomeric material caused multiple microcracks under dry conditions. Oil-lubricated elastomeric gear controlled crack growth at the tooth root and changed the cracking mode from tensile to shear under the high load condition.