Sustainability and performance assessment of gear hobbing under different lubrication environments for manufacturing of 20MnCr5 spur gears

Sustainability of a gear machining process is adversely affected by large amount use of synthetic machining fluids which harm the environmental and human health. This concern has necessitated development and/or explo-ration of innovative options without compromising quality and productivity of gears. This paper describes assessment of sustainability and performance of gear hobbing for manufacturing of spur gears made of 20MnCr5 under different lubrication environments referred as hobbing without any lubrication (HWAL), hobbing with minimum quantity lubrication (HWMQL), and hobbing with flood lubrication (HWFL). Type of lubricant and its consumption, particulate emissions, their toxicity, fumes generation, energy consumption and hob wear have respectively been used as indicators for environmental, social, and economic aspects of sustainability. Gear quality in terms of microgeometry deviation parameters and flank roughness; and material removal rate have been used for performance assessment of HWMQL, HWFL, and HWAL. This study reveals that HWMQL consumes only about 4-5% of lubricant than HWFL; increases hob cutter life by 1.5 times; improves productivity by 27.2%; and consumes 27.8% less specific energy than HWFL. HWMQL also gives good air quality at the workplace with lesser nontoxic particulate emissions and lower fumes generation. Moreover, spur gears manufactured by HWMQL had minimum microgeometry deviations and better flank finish. This study establishes HWMQL environment as the most promising alternative for sustainable manufacturing of good quality spur gears with high productivity.