Abstract:Following a comprehensive review on titanium machining and methods of cutting fluid application, this paper presents a new Controlled cutting fluid impinging supply system (Cut-list) developed to deliver an accurate amount of cutting fluid into the machining zone via well-positioned coherent nozzles based on the calculation of the heat generated. The performance of the new system was evaluated against a conventional flood cutting fluid supply system during step shoulder milling of Ti-6Al-4V using vegetable oil-based cutting fluid. The comparison was performed at different cutting speeds and feed rates. Comparison measures/indicators were cutting force, workpiece temperature, tool flank wear, burr formation and average surface roughness (Ra). The new system provided significant reductions in cutting fluid consumption of up to 42%. Additionally, reductions in cutting force, tool flank wear and burr height of 16.41%, 46.77%, and 31.70% were recorded, respectively. Smaller Ra values were also found with the use of the new system.

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Microstructure and chip formation were evaluated during the step shoulder down-milling of Ti-6Al-4V using a water-miscible vegetable oil-based cutting fluid. Experiments were conducted using the Cut-list fluid supply system previous developed by the authors and a conventional cutting fluid supply system. A thin plastically deformed layer below the machined surface was observed during the metallurgical investigation of the surfaces produced using both systems. Despite noticeable reductions in cutting fluid consumption achieved by Cut-list, no significant disparity was found in microstructural damage. The microstructure of the machined surfaces was strongly affected by cutting speed and fluid flow rate with a discontinuous serrated chip being the principal type. However, increases in cutting fluid flow rate associated with increased cutting speed significantly changed chip morphology where average distance between chip segments increased with cutting speed. Cut-list produced smaller saw-tooth height and larger segmented width, while the transition from aperiodic to periodic serrated chip formation was governed by cutting speed and feed rate. Chip segmentation frequency and shear angle were also sensitive to cutting speed.

This paper presents the development of a new controlled cutting fluid impinging supply system (Cut-list) to deliver an accurate quantity of cutting fluid into machining zones through precisely oriented coherent round nozzles. The performance of the new system was evaluated against a conventional system during the step shoulder milling of Ti-6Al-4V using a water-miscible vegetable oil-based cutting fluid, which was phase 1 in this comprehensive study. The use of Cut-list resulted in a significant reduction up to 42% in cutting fluid consumption as well as reductions in cutting force, tool flank wear, average surface roughness (R a ) and burr height (Gariani et al. in Appl Sci 7(6):560, 2017). This paper details phase 2 of the study which was aimed to investigate the effects of working conditions, nozzle positions/angles and impinging distances on key process measures including cutting forces, workpiece temperature, tool wear, burr formation and average surface roughness of the machined surface. Feed rate showed a significant effect on mean values of cutting force, burr formation and surface roughness, whereas average workpiece temperature and flank wear values are very sensitive to cutting speed. Nozzle position at a 15°angle in the feed direction and 45°/60°against feed direction assisted in minimising workpiece temperature. An impinging distance of 55/75 mm is also necessary to control burr formation, workpiece temperature and average surface roughness. It can be concluded that Cut-list gave promising results compared to conventional flood cooling systems in terms of the evaluated machining outputs. Therefore, the new system can be considered as a feasible, efficient and ecologically beneficial solution, giving less fluid consumption in machining processes.

The paper details experimental and optimisation results for the effect of cutting fluid concentration and operating parameters on the average surface roughness (Ra) and tool flank wear (VB) when flooded turning of Ti-6Al-4V using water-miscible vegetable oil-based cutting fluid. Cutting fluid concentration, cutting speed, feed rate and cutting tool were the control variables. Response Surface Methodology (RSM) was employed to develop an experimental design and optimise Ra and VB using linear models. The study revealed that cutting fluid concentration has a little influence on Ra and VB performance while Ra was strongly affected by feed rate and cutting tool type. The developed empirical model also suggested that the best parameters setting to minimise Ra and VB are 5%, 58 m/min, 0.1 mm/rev for cutting fluid concentration, cutting speed and feed rate, respectively, using H13A tool. At this setting, the predicted surface roughness and tool wear were 0.48 and 30 µm, respectively. In the same vein, tool life and micro-hardness tests were performed at the suggested optimum cutting condition with different cutting speeds. A notable decrease in tool life (82.3%) was obtained when a higher cutting speed was used.

This paper details experimental results when turning Ti-6Al-4V using water-miscible vegetable oil-based cutting fluid. The effects of coolant concentration and working conditions on tool flank wear and tool life were evaluated. L27 fractional factorial Taguchi array was employed. Tool wear (VBB) ranged between 28.8 and 110 µm. The study concluded that a combination of VOs based cutting fluid concentration (10%), low cutting speed (58 m/min), feed rate (0.1mm/rev) and depth of cut (0.75mm) is necessary to minimise VBB. Additionally, it is noted that tool wear was significantly affected by cutting speeds. ANOVA results showed that the cutting fluid concentration is statistically insignificant on tool flank wear. A notable increase in tool life (TL) was recorded when a lower cutting speed was used.

The paper details experimental and optimisation results for the effect of cutting fluid concentration and operating parameters on the average surface roughness (Ra) and tool flank wear (VB) when flooded turning of Ti-6Al-4V using water-miscible vegetable oil-based cutting fluid. Cutting fluid concentration, cutting speed, feed rate, and cutting tool were the control variables. Response surface methodology (RSM) was employed to develop an experimental design and optimise Ra and VB using linear models. The study revealed that cutting fluid concentration has a little influence on Ra and VB performance, while Ra was strongly affected by feed rate and cutting tool type. The developed empirical model also suggested that the best parameters setting to minimise Ra and VB are 5%, 58 m/min and 0.1 mm/rev for cutting fluid concentration, cutting speed, and feed rate, respectively, using H13A tool. At this setting, the predicted surface roughness and tool wear were 0.48 and 30 μm, respectively. In the same vein, tool life and micro-hardness tests were performed at the suggested optimum cutting condition with different cutting speeds. A notable decrease in tool life (82.3%) was obtained when a higher cutting speed was used.