Evaluation of size effect and improvement in surface characteristics using sunflower oil-based MQL for sustainable micro-endmilling of Inconel 718

The increased demand for smaller features leads to miniaturization of components in many areas such as aerospace, biomedical, and electronic industry. Since the tribological performance of the machined components is highly influenced by surface characteristics, the analysis of environmental-friendly lubrication techniques such as minimum quantity lubrication (MQL) using vegetable oil is an important area of interest for the sustainable machining. MQL is a promising technique that minimizes the usage of lubricant, thus enhancing sustainability. This work aimed at studying the size effect and improvement in surface characteristics of sunflower oil-based MQL-assisted micro-endmilling of Inconel 718 with respect to dry machining. Chip analysis was also conducted to confirm the findings. Effects of feed/tooth on surface roughness, chip formation, top burr height, and top burr width for both dry and MQL conditions were studied. The size effect was found to be up to a feed/tooth value near to the cutter edge radius (3 mu m). Minimum uncut chip thickness was found to be near to 0.3 times the cutter edge radius. It was found that almost 32% average reduction in areal surface roughness, 36% average reduction in top burr width, and 37% average reduction in top burr height were observed for sunflower oil-based MQL-assisted micro-endmilling of Inconel 718 compared to dry condition. Finally, it was concluded that the application of sunflower oil-based MQL enables micro-endmilling of Inconel 718 for higher feed/tooth range with good surface quality.