Search Results (8)

The efficiencies of additive manufacturing (AM) over conventional processes have enabled the rapid production of aluminum (Al) alloys with AM. Because laser beam powder bed fusion (LB-PBF) parts do not offer the surface quality and geometrical accuracy for direct use, the functional surfaces of LB-PBF parts are usually machined by subtractive machining. The machinability of LB-PBF AlSi10Mg was studied in dry, MQL (used corn oil), and cryo-LN₂ cutting environments across distinct speed–feed combinations using CVD-AlTiN-coated carbide inserts, and surface integrity and tool life were quantified in terms of surface roughness (Ra) and flank wear (Vb), respectively. The lowest Ra (0.98–1.107 μm) was obtained with cryo-LN₂, followed by MQL and dry cutting environments, because the trends observed were consistent with the surface mechanisms observed in 3D topography and bearing curves. Similarly, the tool wear results mirrored the Ra results, lowest with LN₂ (0.087–0.110 mm), due to improved thermal management, reduced adhesion and abrasion, and shorter contact length. Cryo-LN₂ provided the best surface finish and tool life among all tested environments. To enable data-driven prediction, the limited dataset was augmented using SMOTE, and machine learning (ML) models were trained to predict Ra and Vb. CatBoost was found to yield the best Ra predictions (R² = 0.9090), while Random Forest and XGBoost yielded the best Vb predictions (R² ≈ 0.878). Full article

The move toward environmentally friendly methods in the global manufacturing sector has led to the use of minimum quantity lubrication (MQL) as an eco-friendly alternative to traditional flood cooling. However, the natural limits of MQL in high-performance settings have led to the use of nanotechnology, which has resulted in the creation of nanofluids, engineered colloidal suspensions that significantly improve the thermophysical and tribological properties of base fluids. This paper gives a complete overview of the latest developments in nanofluid technology for use in machining. It starts with the basics of MQL and the rules for making, describing, and keeping nanofluids stable. The review examines the application and effectiveness of single and hybrid nanofluids in various machining processes. It goes into detail about how they improve tool life, surface integrity, and overall efficiency. It also examines the benefits of integrating nanofluid-assisted MQL (NMQL) with more advanced and hybrid systems, including cryogenic cooling (cryo-NMQL), ultrasonic atomization, electrostatic–magnetic assistance, and multi-nozzle delivery systems. The paper also gives a critical look at the main problems that these technologies face, such as the long-term stability of nanoparticle suspensions, their environmental and economic viability as measured by life cycle assessment (LCA), and the important issues of safety, toxicology, and disposal. This review gives a full picture of the current state and future potential of nanofluid-assisted sustainable manufacturing by pointing out important research gaps, like the need for real-time LCA data, cost-effective scalability, and the use of artificial intelligence (AI) to improve processes, and by outlining future research directions. Full article

Nickel-based superalloy Hastelloy C276 is widely used in high-performance industries due to its strength, corrosion resistance, and thermal stability. However, these same properties pose substantial challenges in machining, resulting in high tool wear, surface defects, and dimensional inaccuracies. This study investigates methods to enhance machining performance and surface quality by evaluating the tribological behavior of TiSiN/TiAlN-coated carbide inserts under six cooling and lubrication conditions: dry, MQL with coconut oil, Cryo-LN₂, Cryo-LCO₂, MQL–Cryo-LN₂, and MQL–Cryo-LCO₂. Open-slot finishing was performed at constant cutting parameters, and key indicators such as cutting zone temperature, tool wear, surface roughness, chip morphology, and microhardness were analyzed. The hybrid MQL–Cryo-LN₂ approach significantly outperformed other methods, reducing cutting zone temperature, tool wear, and surface roughness by 116.4%, 94.34%, and 76.11%, respectively, compared to dry machining. SEM and EDS analyses confirmed abrasive, oxidative, and adhesive wear as the dominant mechanisms. The MQL–Cryo-LN₂ strategy also lowered microhardness, in contrast to a 39.7% increase observed under dry conditions. These findings highlight the superior performance of hybrid MQL–Cryo-LN₂ in improving machinability, offering a promising solution for precision-driven applications. Full article

Hard turning is a precision machining process used to cut materials with hardnesses exceeding 45 HRC using single-point tools. It offers an efficient alternative to traditional grinding for finishing operations in manufacturing. This paper explores the machinability of hardened AISI 4340 steel for a hard turning process utilizing dry and cryogenic (Cryo) plus minimum quantity lubrication (MQL) (Cryo+MQL) techniques, focusing on critical machinability aspects such as cutting force, surface roughness, and tool life. The orthogonal dry turning was performed with a cutting speed (V) ranging from 300–400 m/min, a feed rate (f) between 0.05 and 1 mm/rev, and a depth of cut (doc) from 0.1 to 0.3 mm. A statistical analysis of the obtained results revealed that the feed rate was the most influential parameter, contributing 50.69% to the main cutting force and 80.03% to surface roughness. For tool life, cutting speed was identified as the dominant factor, with a contribution rate of 39.73%. Multi-objective optimization using Grey relational analysis (GRA) identified the optimal machining parameters for the hard turning of AISI 4340 alloy steel as V = 300 m/min, f = 0.05 mm/rev, and doc = 0.1 mm. The Cryo+MQL technique was subsequently applied to these parameters, yielding significant improvements, with a 48% reduction in surface roughness and a 184.5% increase in tool life, attributed to enhanced lubrication and cooling efficiency. However, a slight 4.6% increase in cutting force was observed, likely due to surface hardening induced by the low-temperature LN₂ cooling. Furthermore, reduced adhesion and tool fracture on the principal cutting edge under Cryo+MQL conditions justify the superior surface quality and extended tool life achieved. This research highlights the industrial relevance of hybrid lubrication in addressing challenges associated with hard turning processes. Full article

Although chip morphology changes according to the machining method and related cutting parameters, chip formation affects the quality of the machined surface. In this context, it is very important to understand the relationship between chip morphology and surface quality, especially in materials that are difficult to machine. In the presented study, the changes in chip morphology, surface morphology, and surface quality criteria (Ra and Rz) that occurred during the milling of precipitation-hardened steel in different cutting environments were analyzed. Milling experiments were carried out in dry, MQL (minimum quantity lubrication), nano-MQL (graphene), nano-MQL (hBN), Cryo, and Cryo-MQL environments using TiAlN-coated inserts and three different cutting speeds and feed rates. While the highest values in terms of Ra and Rz were measured in dry machining, the minimum values were obtained in a nano-MQL (hBN) cutting environment. Due to the lubrication and low friction provided by the MQL cutting environment, chips were formed in thinner segmented forms. This formation reduced the chip curve radius and thus provided a more stable surface morphology. On the other hand, Cryo-ambient gas could not effectively leak into the cutting zone due to the intermittent cutting process, but it increased the brittleness of the chips with the cooling effect and provided a similar surface morphology. The values of minimum Ra and Rz were obtained as 0.304 mm and 1.825 mm, respectively, at a 60 m/min cutting speed and 0.04 mm/rev feed. Consequently, the use of nano-MQL cutting medium is seriously recommended in terms of surface quality in milling operations of difficult-to-machine materials. Full article

This research analyses the viability of using cryogenic cooling combined with MQL (minimum quantity lubrication) lubrication, under CryoMQL technology, as a cutting fluid in the industrial environment to justify the increase in the environmental footprint generated by its use compared to MQL in stand-alone mode. For this analysis, a set of milling tests were carried out on carbon steel AISI 1045, which is one of the most commonly used materials in the business day-to-day. In this set of tests, the evolution of cutting edge wear and energy consumption of both technologies were recorded to check their tool life through technological and environmental analysis. Thus, we sought to discern whether the energy savings derived from the machining process make up for the greater environmental footprint initially generated by the use of CryoMQL technology itself. The results obtained show how the use of CryoMQL not only increased tool life, but also allowed an increase in productivity by increasing cutting speeds by 18%; in other words, thanks to this technology, a more technologically advanced and environmentally friendly process is obtained. By increasing tool life by 30%, a reduction in energy consumption is achieved together with cost savings, which implies that ECO2 machining has economic and ecological benefits. Full article

Tribological properties are directly related to cutting efficiency. To achieve high machinability performances, sustainable coolants (minimum quantity lubricant (MQL), cryogenic etc.) have been used instead of conventional cutting fluids in recent years. This study used MQL and cryogenic-cooling techniques while milling Al-based hybrid composites. The effects of different cutting environments on flank wear, surface roughness, cutting temperature, and energy consumption were analyzed according to the Taguchi method. According to the findings, the best cutting environment for surface roughness, flank wear, and cutting temperature is the cryo-LN₂-assisted cooling technique. In terms of energy consumption, MQL was found to be more efficient than cryo-LN₂ and dry environments. According to SEM/EDS analysis, BUE formation was observed at the tool edges during milling in dry conditions. It was determined that cutting tool surfaces are smoother in MQL and cryo-LN₂ environments. The effect ratios of control factors on response parameters were determined according to Taguchi analysis. As a result, it was concluded that MQL and cryo-LN₂ strategies could be evaluated within the scope of sustainable conditions. Full article

In recent years, hard turning has been found to be a well-known substitute for traditional grinding for acquiring the finish quality of hardened steel without sacrificing productivity. There are many issues that should be carefully understood and dealt with to attain efficacious performance in hard turning. This article discusses modern manufacturing challenges with a focus on analyzing the current state of the art of the hard turning process in terms of ensuring more environmentally friendly manufacturing through the use of greener cooling methods such as dry, wet/flood cooling, the minimum quantity of lubricant (MQL), high-pressure jet cooling, solid lubricant, nanofluids, ionic liquids (ILs), cryogenic cooling, and hybrid cooling. Nanofluids combined with the MQL system were found to be the superior cooling technique in comparison to dry, wet/flood, and MQL. Cryo-machining also provided superior performance by limiting the cutting temperature during hard turning. The performance of hybrid cooling (MQL + cryogenic) seems to have been superior to MQL and cryogenic coolant alone because it combined the benefits of lubrication and cooling from MQL and cryogenic systems, respectively. The addition of ILs to base fluids or nanofluids improves the thermal properties of the mixed fluid, resulting in better surface quality, lower tool wear, and longer tool life. Furthermore, the purpose of this study is to summarize the various LCA software used for analyzing the sustainability of the hard turning process. Overall, this paper can serve as a resource for researchers and manufacturers working in the field of sustainable machining. Full article