Specific cutting energy of Inconel 718 under dry, chilled-air and minimal quantity nanolubricants

Abstract

Efficient and optimal consumption of energy in manufacturing industries appear as vital strategies towards minimisation of cost due to the uncertainties of energy prices apart from emphasising on the environmental sustainability of manufacturing processes. It has been reported that energy efficiency for material removal processes can be quite small compared to the total energy for the machine tool operation. Notwithstanding this, due to novel strategies alongside with a wide process window of machining operations being proposed from research work, the need to reevaluate the energy efficiency in metal machining is inevitable. Coolant strategy in machining processes is capable of reducing the energy consumption during the cutting process, due to the cooling and lubricating effects provided by the coolant system. Hence, in this work, the specific energy consumption during turning of Inconel 718 with different coolant approaches namely; dry, vortex-tube chilled air, and nanolubricants enhanced minimum quantity lubricant (MQL) were compared. A general purpose coated carbide tool was used with a constant depth of 0.25 mm. Four different feed rates in the range of 0.1 to 0.4 mm/rev with six different cutting speeds of 60 to 110 m/min were tested to evaluate the specific cutting energy. For each of the cutting speeds and coolant approaches, the specific cutting energies were determined from the gradient of power consumption against material removal rate. Apart from that, the power law relationships between the feed rate and specific cutting energy were also established for each of the coolant approaches. Experimental results suggest that the use of aluminium oxide nanolubricants enhanced with MQL system leads to a marginal reduction in specific cutting energy as to that of dry and vortex chilled air. The specific cutting energy was the highest for the vortex chilled air, although it was earlier anticipated that dry cutting should be poor in term of energy consumed upon this short-duration machining.