Some investigations in grindability improvement of Inconel 718 under ecological grinding

Abstract

This work explores the improvement in grinding characteristics of Inconel 718 (IN718) using soluble oil under minimum quantity lubrication and liquid nitrogen (LN2) environments. The coolant flow rate in minimum quantity lubrication and LN2 grinding has been regulated through indigenously developed setups. Grinding performance has been studied in terms of on-machine measured grinding forces and centre line average surface roughness (Ra). The obtained grinding characteristics have been compared with the outcomes under dry and wet grinding. Surface integrity of ground surface, wheel morphology, and chip formation characteristics has been studied using scanning electron microscope, energy dispersive X-ray spectroscopy, and atomic force microscopy. Analysis of variance has been carried out to capture the variability in the experimental data for tangential forces and Ra. The main effect of the factors and their first-order interactions have been considered, and second-order regression equations have been developed using response surface methodology. LN2 grinding has been proved to be more efficient as it yielded lowest grinding forces, least oxidation, minimal ground surface damage and better surface integrity. The occurrence of almost circular chips in dry grinding indicates severe oxidation, whereas small C-type chips formed under minimum quantity lubrication and LN2 conditions indicate effective cooling under these environments. The energy dispersive X-ray spectroscopy analysis of the ground surfaces also supports these results through the occurrence of the highest oxidation in dry grinding. From this work, it has been concluded that LN2 and minimum quantity lubrication grinding offer a clean and effective means to improve grinding performance of IN718 compared to dry and wet grinding.

Experimental and statistical investigation of the effects of MQL, dry and wet machining on machinability and sustainability in turning of AISI 4140 steel

“…From these, the most suitable cut-off length for our purposes (turning) was determined as 0.8 mm for Ra values of the machined workpieces. 34,35 While Ra measurements were carried out, measurements were taken from three different points for 5.6 mm from the surfaces of machined workpiece at 0.8 mm of cut-off length; and arithmetical mean of these measured values were calculated. In general, V B is referenced for tool wear measurement since the life of a cutting tool is assessed with real cutting time once V B value reaches at a limited value of 0.3 mm.…”

Improving the Efficiency of Grinding Process Using the Rubber-Pasted Grinding Wheel

“…Many solutions are proposed in order to reduce the amount of heat transferred to the surface of the part, such as using a appropriate cooling/lubrication regime [6,7]; special cooling methods, for example, minimum quantity lubrication (Minimum Quantity Lubricant -MQL) [8][9][10]; an open-structure grinding wheel for guiding the coolant from the inside of the spindle to the grinding zone through the gap between the abrasive grains [3]; the grinding with radial holes for guiding the coolant in the same way [3]. However, the fabrication of the open-structure grinding wheel is not applicable if the binder is ceramic and rubber, whereas these two types of binder are probably most common for producing grinding wheels, especially the ceramic.…”

Experimental evaluation and surface integrity analysis of cryogenic coolants approaches in the cylindrical plunge grinding

“…More importantly, from this 30%, between 7 and 17% of the cost is caused by coolant systems 5 . Traditional coolant systems are based on water-miscible cutting fluids, and their high spatial volume requires large storage capacity and high-powered pumps, which further increase the grinding costs 6 . In addition to this impact on the bottom line, coolant systems have a harmful effect on the environment and pose health risks to the operator.…”

“…Nonetheless, Ra roughness and forces did not present significant differences in comparison with conventional grinding processes. Four years later, Sinha et al 6 compared the use of MQL and LN 2 environment to dry grinding of Inconel 718. They found that using MQL and LN 2 reduced cutting forces and promoted better grit-workpiece interaction.…”