Biodegradation and hard machining performance comparison of ecofriendly cutting fluid and mineral oil using flood cooling and minimum quantity cutting fluid techniques

As manufacturing advances, there is a growing demand for harder materials in various fields, such as aerospace and defence. Hard materials are difficult to produce, and hard machining causes high cutting temperatures, which increase cutting force and affect the surface finish of the product. To lower the cutting forces and obtain better surface finishes on the workpiece, metal cutting fluids are generally preferred. However, the use of these fluids has been questioned by many researchers recently. Mineral oil-based conventional cutting fluids are essentially crude petroleum derivatives that have low biodegradability. Therefore, these fluids are associated with a high risk of environmental pollution (air, soil, water). In this study, the characteristics and biodegradable potential of bio-cutting fluid (BCF) and commercially available mineral oil (MO)-based cutting fluid are compared, in addition to their hard machining performance during the machining of hardened AISI H-13 steel. To minimise the usage of cutting fluid during hard machining, an indigenously designed and fabricated minimum quantity cutting fluid (MQCF) application system is used. In the MQCF system, pressurised air is mixed internally with the cutting fluid, forming a uniform mist at the nozzle exit. The same is delivered to the machining region. The influence of flood cooling and MQCF techniques using both BCF and MO on the cutting force, feed force, coefficient of friction, and workpiece surface roughness, which were studied during hard machining with industrial feed-speed combinations. The pressurised MQCF mist jet reduces the cutting zone contact length, because of its optimised parameters and the better lubricating characteristics of BCF. The experimental results show a significant reduction in cutting force, feed force, coefficient of friction, and surface roughness for MQCF. (C) 2017 Elsevier Ltd. All rights reserved.