Review on Cutting Fluids: Formulation, Chemistry and Deformulation.

This comprehensive review offers a chemical analysis of cutting fluids, delving into both their formulation and deformulation processes. The study covers a wide spectrum of cutting fluid formulations, ranging from simple compositions predominantly comprising oils, whether mineral or vegetable, to emulsions. The latter involves the integration of surfactants, encompassing both nonionic and anionic types, along with a diverse array of additives. Concerning oils, the current trend leans towards the use of vegetable oils instead of mineral oils for environmental reasons. As vegetable oils are more prone to oxidation, chemical alterations, the addition of antioxidant may be necessary. The chemical aspects of the different compounds are scrutinized, in order to understand the role of each component and its impact on the fluid's lubricating, cooling, anti-wear, and anti-corrosion properties. Furthermore, the review explores the deformulation methodologies employed to dissect cutting fluids. This process involves a two-step approach: separating the aqueous and organic phases of the emulsions by physical or chemical treatments, and subsequently conducting a detailed analysis of each to identify the compounds. Several analytical techniques, including spectrometric or chromatographic, can be employed simultaneously to reveal the chemical structures of samples. This review aims to contribute to the improvement of waste treatment stemming from cutting fluids. By gathering extensive information about the formulation, deformulation, and chemistry of the ingredients, there is a potential to enhance the waste management and disposal effectively.

Standalone Sensors System for Real-Time Monitoring of Cutting Emulsion Properties with Adaptive Integration in Machine Tool Operation.

This paper presents a novel cutting fluid monitoring sensor system and a description of an algorithm framework to monitor the state of the cutting emulsion in the machine tool sump. One of the most frequently used coolants in metal machining is cutting emulsion. Contamination and gradual degradation of the fluid is a common occurrence, and unless certain maintenance steps are undertaken, the fluid needs to be completely replaced, which is both un-economical and non-ecological. Increasing the effective service life of the cutting emulsion is therefore desired, which can be achieved by monitoring the parameters of the fluid and taking corrective measures to ensure the correct levels of selected parameters. For this purpose, a multi-sensor monitoring probe was developed and a prototype device was subsequently created by additive manufacturing. The sensor-carrying probe was then placed in the machine tool sump and tested in operation. The probe automatically takes measurements of the selected cutting emulsion properties (temperature, concentration, pH, level height) in set intervals and logs them in the system. During the trial run of the probe, sensor accuracy was tracked and compared to reference measurements, achieving sufficiently low deviations for the purpose of continuous operation.

Cellulose nanocrystals as sustainable additives in water-based cutting fluids.

Cutting fluid is indispensable in the machining industry as a fluid for lubrication and cooling in the metalworking process due to their ability to significantly improve various properties of cutting fluid. Castor oil, as a common base oil and additive in cutting fluid, can be grafted onto the surface of cellulose nanocrystals (CNC) to further enhance the lubricating properties of cutting fluid. It has been shown that cellulose nanocrystals and castor oil modified cellulose nanocrystals (CO-CNC) as additives in cutting fluid have good dispersion stability and can effectively improve the lubricating properties. When the amount of CNC or CO-CNC was added in the working fluid at about 0.5 wt%, the friction coefficient was significantly reduced. According to the results from this study, cellulose nanocrystal is a promising candidate as the nontoxic and renewable additive for the improvement of diverse performances for the water-based cutting fluid.

End-stage renal disease and metalworking fluid exposure.

OBJECTIVE: Despite increasing prevalence of end-stage renal disease (ESRD), little attention has been directed to how occupational exposures may contribute to risk. Our objective was to investigate the relationship between metalworking fluids (MWF) and ESRD in a cohort of 36 703 male autoworkers. METHODS: We accounted for competing risk of death, using the subdistribution hazard approach to estimate subhazard ratios (sHRs) and 95% CIs in models with cubic splines for cumulative exposure to MWF (straight, soluble or synthetic). RESULTS: Based on 501 ESRD cases and 13 434 deaths, we did not observe an association between MWF and ESRD overall. We observed modest associations between MWF and ESRD classification of glomerulonephritis and diabetic nephropathy. For glomerulonephritis, the 60th percentile of straight MWF was associated with an 18% increased subhazard (sHR=1.18, 95% CI: 0.99 to 1.41). For diabetic nephropathy, the subhazard increased 28% at the 60th percentile of soluble MWF (sHR=1.28, 95% CI: 1.00 to 1.64). Differences by race suggest that black males may have higher disease rates following MWF exposure. CONCLUSIONS: Exposure to straight and soluble MWF may be related to ESRD classification, though this relationship should be further examined.

Effect of Different Cooling Strategies on Surface Quality and Power Consumption in Finishing End Milling of Stainless Steel 316.

In this paper, an experimental investigation into the machinability of AISI 316 alloy during finishing end milling operation under different cooling conditions and with varying process parameters is presented. Three environmental-friendly cooling strategies were utilized, namely, dry, minimal quantity lubrication (MQL) and MQL with nanoparticles (Al2O3), and the variable process parameters were cutting speed and feed rate. Power consumption and surface quality were utilized as the machining responses to characterize the process performance. Surface quality was examined by evaluating the final surface roughness and surface integrity of the machined surface. The results revealed a reduction in power consumption when MQL and MQL + Al2O3 strategies were applied compared to the dry case by averages of 4.7% and 8.6%, respectively. Besides, a considerable reduction in the surface roughness was noticed with average values of 40% and 44% for MQL and MQL + Al2O3 strategies, respectively, when compared to the dry condition. At the same time, the reduction in generated surface roughness obtained by using MQL + Al2O3 condition was marginal (5.9%) compared with using MQL condition. Moreover, the results showed that the improvement obtained in the surface quality when using MQL and MQL + Al2O3 coolants increased at higher cutting speed and feed rate, and thus, higher productivity can be achieved without deteriorating final surface quality, compared to dry conditions. From scanning electron microscope (SEM) analysis, debris, furrows, plastic deformation irregular friction marks, and bores were found in the surface texture when machining under dry conditions. A slight smoother surface with a nano-polishing effect was found in the case of MQL + Al2O3 compared to the MQL and dry cooling strategies. This proves the effectiveness of lubricant with nanoparticles in reducing the friction and thermal damages on the machined surface as the friction marks were still observed when machining with MQL comparable with the case of MQL + Al2O3.

Performance Evaluation of Vegetable Oil-Based Nano-Cutting Fluids in Environmentally Friendly Machining of Inconel-800 Alloy.

Recently, the application of nano-cutting fluids has gained much attention in the machining of nickel-based super alloys due their good lubricating/cooling properties including thermal conductivity, viscosity, and tribological characteristics. In this study, a set of turning experiments on new nickel-based alloy i.e., Inconel-800 alloy, was performed to explore the characteristics of different nano-cutting fluids (aluminum oxide (Al2O3), molybdenum disulfide (MoS2), and graphite) under minimum quantity lubrication (MQL) conditions. The performance of each nano-cutting fluid was deliberated in terms of machining characteristics such as surface roughness, cutting forces, and tool wear. Further, the data generated through experiments were statistically examined through Box Cox transformation, normal probability plots, and analysis of variance (ANOVA) tests. Then, an in-depth analysis of each process parameter was conducted through line plots and the results were compared with the existing literature. In the end, the composite desirability approach (CDA) was successfully implemented to determine the ideal machining parameters under different nano-cutting cooling conditions. The results demonstrate that the MoS2 and graphite-based nanofluids give promising results at high cutting speed values, but the overall performance of graphite-based nanofluids is better in terms of good lubrication and cooling properties. It is worth mentioning that the presence of small quantities of graphite in vegetable oil significantly improves the machining characteristics of Inconel-800 alloy as compared with the two other nanofluids.

Lung cancer mortality and exposure to synthetic metalworking fluid and biocides: controlling for the healthy worker survivor effect.

OBJECTIVES: Synthetic metalworking fluids (MWFs), widely used to cool and lubricate industrial machining and grinding operations, have been linked with increased risk of several cancers. Estimates of their relation with lung cancer, however, are inconsistent. Controlling for the healthy worker survivor effect, we examined the relations between lung cancer mortality and exposure to synthetic MWF, as well as to biocides added to water-based fluids to control microbial growth, in a cohort of autoworkers. Biocides served as a marker for endotoxin, which has reported antitumour effects, and were hypothesised to be the reason prior studies found reduced lung cancer risk associated with exposure to synthetic fluids. METHODS: Using the parametric g-formula, we estimated risk ratios (RRs) comparing cumulative lung cancer mortality under no intervention with what would have occurred under hypothetical interventions reducing exposure to zero (ie, a ban) separately for two exposures: synthetic fluids and biocides. We also specified an intervention on synthetic MWF and biocides simultaneously to estimate joint effects. RESULTS: Under a synthetic MWF ban, we observed decreased lung cancer mortality risk at age 86, RR=0.96 (0.91-1.01), but when we also intervened to ban biocides, the RR increased to 1.03 (0.95-1.11). A biocide-only ban increased lung cancer mortality (RR=1.07 (1.00-1.16)), with slightly larger RR in younger ages. CONCLUSIONS: Findings suggest a modest positive association for synthetic MWF with lung cancer mortality, contrary to the negative associations reported in earlier studies. Biocide exposure, however, was inversely associated with risk of lung cancer mortality.

Feasibility of spent metalworking fluids as co-substrate for anaerobic co-digestion.

In this paper, anaerobic co-digestion of spent metalworking fluids (SMWF) and pig manure (PM) was evaluated. Three SMWF:PM ratios were tested in order to find the highest process efficiency. The best results (COD removal efficiencies of 74%) were achieved co-digesting a mixture with a SMWF:PM ratio of 1:99, w/w(1) (corresponding to 3.75mL SMWF/Lreactor week), which indicates that SMWF did not affect negatively PM degradation. Furthermore, two different weekly SMWF pulse-frequencies were performed (one reactor received 1 pulse of 3.75mL/Lreactor and the other 3 pulses of 1.25mL/Lreactor) and no differences in COD removal efficiency were observed. Microbiology analysis confirmed that Pseudomonas was the predominant genus when treating anaerobically SMWF and the presence of a higher fraction of Archaea was indicative of good digester performance. This study confirms the feasibility of anaerobic co-digestion as an appropriate technology for treating and valorising SMWF.