**4. Conclusions**

In this review, we attempted to highlight the properties and associated drawbacks of the mineral oil-based MWFs and to perform a comprehensive literature review on the potential alternatives to mineral oil-based MWFs, such as vegetable oil-based MWFs; and we attempted to investigate other sustainable machining operations, including the high-pressure coolant, dry machining, MQL, and the nanofluid methods. The pros and cons of all of the associated alternatives were critically reviewed in terms of their applicability, adaptability, cost-effectiveness, and environmental impact so that an unbiased analysis could be performed for the use of MWFs in machining applications. As seen from the comprehensive literature review, machining is one of the main parts of every manufacturing plant and it cannot be ignored, and MWFs play a key role in the cost of machining. Cutting fluids have widely been used in conventional machining process for cooling applications, but they are a main factor of increased costs along with adverse effects on the environment and health of workers/operators. Therefore, it is necessary to minimize the utilization of mineral oil-based MWFs, and instead adopt vegetable oil-based MWFs and other sustainable methods such as the MQL, dry machining, high pressure coolant, and nanofluid methods, among other alternatives. These alternative techniques not only have been shown to reduce the cost of manufacturing by 10% to 17%, but also have a more positive impact on the environment by eliminating issues concerning cutting fluid disposal and by minimizing the contact of the workers with the MWFs, contact that may result in severe diseases. These techniques demonstrated very promising results as compared with the conventional methods where mineral oil-based MWFs were used in the machining process. By keeping this in view with the latest demands of industrial sectors and modern machining process requirements, these techniques are one of the best options to opt for, allowing for the implementation of sustainable machining processes in replacement of traditional methods.
