Machining operations are very common for the production of auto parts, i.e., connecting rods, crankshafts, etc. In machining, the use of cutting oil is very necessary, but it leads to higher machining costs and environmental problems. About 17% of the cost of any product is associated with cutting fluid, and about 80% of skin diseases are due to mist and fumes generated by cutting oils. Environmental legislation and operators’ safety demand the minimal use of cutting fluid and proper disposal of used cutting oil. The disposal cost is huge, about two times higher than the machining cost. To improve occupational health and safety and the reduction of product costs, companies are moving towards sustainable manufacturing. Therefore, this review article emphasizes the sustainable machining aspects of steel by employing techniques that require the minimal use of cutting oils, i.e., minimum quantity lubrication, and other efficient techniques like cryogenic cooling, dry cutting, solid lubricants, air/vapor/gas cooling, and cryogenic treatment. Cryogenic treatment on tools and the use of vegetable oils or biodegradable oils instead of mineral oils are used as primary techniques to enhance the overall part quality, which leads to longer tool life with no negative impacts on the environment. To further help the manufacturing community in progressing towards industry 4.0 and obtaining net-zero emissions, in this paper, we present a comprehensive review of the recent, state of the art sustainable techniques used for machining steel materials/components by which the industry can massively improve their product quality and production.

Surface finish has an essential role in superior performance of machined products which becomes crucial for sophisticated applications like invasive biomedical implants and aerospace components. Ti6Al4V is popular in these applications due to its exceptional characteristics of weight-to-strength ratio. However, Ti6Al4V is a difficult-to-cut material; therefore, non-traditional cutting techniques especially, electric discharge machining (EDM), are widely adopted for Ti6Al4V cutting. The engagement of nano-powders are used to upsurge the cutting rate and surface quality. Among the different powders, a novel nano-powder additive, i.e., graphene, has not been tested in EDM of Ti6Al4V. Therefore, the potential of nano-graphene is comprehensively investigated herein for roughness perspective in EDM of Ti-alloy. The experimental design is based on Taguchi L18 orthogonal framework which includes six EDM parameters. The experimental findings are thoroughly discussed with statistical tests and physical evidence. The surface quality achieved with an aluminum electrode was found best amongst its competitors, whereas the worst surface asperities were noticed when brass electrode was used under graphene mixed dielectric. Moreover, it is conceived that the positive tool polarity provides lower roughness for all types of electrodes. Furthermore, optimal settings have been developed that warrant a reduction of 61.4% in the machined specimen’s roughness compared to the average roughness value recorded during the experimentation.

Inconel 600 is a Ni-based superalloy having exclusive properties like high strength and stability in harsh conditions. However, its accurate machining is challenging via conventional cutting methodologies. As a result, the use of electric discharge machining is common in cutting Inconel 600 precisely. But the intrinsic issue of overcut associated with traditional EDM limits its appreciation in cutting Ni-based alloy. Moreover, conventional dielectric oil used in EDM releases hazardous fumes and gases that put the operator’s health at risk. Therefore, in this study, six different biodegradable dielectrics have been investigated for their potential in controlling the dimensional overcut, which have yet to be evaluated thoroughly. The performance of biodegradable dielectrics (canola, amla, olive, sunflower, coconut, and mustard oil) against four types of electrode materials has been evaluated using full factorial design in the EDM of Inconel 600. Experimental findings are analyzed with statistical tests and optical/scanning electron microscopic evidence. The experimental results indicated that canola dielectric yield the smallest dimensional overcut. However, combination of sunflower oil and copper electrode proved as second premier case to reduce the overcut. Compared to the conventionally used kerosene oil, the biodegradable dielectrics (canola and sunflower) display a 63% and 1.2-folds reduction in overcut.

No abstract

Electric discharge machining (EDM) has great acceptance in different application sectors to wipe out intrinsic problems, like product miniaturizing and tight tolerances, during the fabrication of micro-size products. Many researchers have worked well in the micro-cutting of various alloys through the EDM process. However, limited work has been reported on the EDM of SS 316 for micro-impression fabrication using EDM. The selection of the best dielectric, electrode material, and powder-based additives has never been targeted so far to have dimensionally accurate micro-impression at an appreciable cutting rate with no/less electrode damage in the EDM of the said alloy. Therefore, in this research, the collective influence of various dielectrics (kerosene oil, transformer oil, and canola oil), powders (alumina, graphite, and silicon carbide), and electrodes (copper, brass, and aluminum) have been comprehensively examined for the fabrication of micro-impressions in AISI 316 using EDM. Taguchi L9 orthogonal technique was applied to study the effect of four input parameters on material removal rate, overcut, and tool wear rate. Results were statistically explored using main effect plots and supplemented by scanning electron microscopy, surface profilometry, and optical microscopy. The results show that material removal and tool wear rates notably improved from the mean value by 29% and 89.4%, respectively, when the machining is carried out under silicon carbide mixed kerosene dielectric against silicon carbide the aluminum tool at a pulse time ratio of 1.5. Furthermore, for dimensional overcut, 5.3 times lesser value is observed from the average magnitude of 0.189 mm when the proposed EDM setup is employed for cutting AISI 316. An optimized setting has also been proposed by grey relational analysis and then validated through a confirmation experiment.