AHP-MARCOS, a hybrid model for selecting gears and cutting fluids

Abstract

Gears are basic elements of transmission and keep machinery and instruments in operation. Over 90% (A.K. Rakhit and ASM International, 2000) [1] of the gears used in industrial applications today are made from alloy steels. When the gear teeth engage the contact between them during operation under dynamic conditions is complex, which leads to several failure modes like micro pitting, scuffing, and wear as a result of rotation. Various attributes of gear materials which are generally considered by a manufacturer are density, tensile strength, shear modulus, yield strength, Brinell hardness and cost. Currently, numerous gear materials are available in the market having their own advantages and disadvantages, an appropriate methodology for selection of material is essential. An appropriate finishing process not only improves surface quality but also reduces errors in its geometry which minimizes the running noise and improves surface integrity of the gear to maximise its load carrying capacity. The cost attributed to finishing typically contributes 15%–25% (Gupta et al., 2017) [2] toward its total manufacturing cost. The amount of heat released at the contact surface during machining of a gear due to friction, is enormous and must be dissipated. Cutting fluids are generally applied to provide lubrication and cooling at the tool and workpiece interface. There are many cutting fluids having different properties, so there is a need for selection of an optimum cutting fluid which will also not degrade the environment. This paper looks at the aspects that can help a designer and a manufacturer in making the best choices. A hybrid multi-criteria decision-making MCDM model Analytic Hierarchy Process - Measurement Alternatives and Ranking according to Compromise Solution (AHP-MARCOS) is used for selection of gear material and cutting fluids. AHP is used to determine weights and MARCOS method is used for selecting the appropriate gear material and also the cutting fluid. The ranking performance is compared with that of the past researchers and how stability of the hybrid model is compared to a similar ranked method.