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Variation of 3 force components when machining the ASTM F-1537 CoCr alloy with cutting speed for dry and cryogenic cooling, with modified and non-modified inserts. a Cutting force, b feed force and c passive force. d Close-up view of the internal cryogenically cooled tool mounted on the dynamometer
Source publication
This paper presents a novel indirect cryogenic cooling system, employing liquid nitrogen (LN2) as a coolant for machining the difficult-to-cut ASTM F-1537 cobalt-chromium (CoCr) alloy. The prototype differs from the already existing indirect cooling systems by using a modified cutting insert that allows a larger volume of cryogenic fluid to flow un...
Citations
... 25 articles [1], [2], [5]- [7], [12], [22], [23], [28]- [46] out of the 54 selected arti-cles cover different designs of CLICCT, 5 articles [6], [29], [36], [38], [43] cover only the FE and CDF simulations of CLICCT and 18 articles describe experimental turning with CLICCT prototypes [1], [2], [5], [7], [12], [28], [30], [32]- [34], [35], [37], [39], [41], [42], [44]- [46] (see Fig. 2). In 6 articles [6], [30], [35], [37], [41], [44] the CLICCT design was defined as "novel" and in 1 article [42] as "innovative". ...
... 25 articles [1], [2], [5]- [7], [12], [22], [23], [28]- [46] out of the 54 selected arti-cles cover different designs of CLICCT, 5 articles [6], [29], [36], [38], [43] cover only the FE and CDF simulations of CLICCT and 18 articles describe experimental turning with CLICCT prototypes [1], [2], [5], [7], [12], [28], [30], [32]- [34], [35], [37], [39], [41], [42], [44]- [46] (see Fig. 2). In 6 articles [6], [30], [35], [37], [41], [44] the CLICCT design was defined as "novel" and in 1 article [42] as "innovative". ...
Near–dry machining and dry machining lead to increased temperature of the cutting tools. To reduce tool wear and extend the tool lifetime, and, eventually, to keep the accuracy of manufactured parts within acceptable limits as long as possible, a sustainable cooling technique is required. The technology of internal cooling of the cutting tool appears to be the most promising, because it allows eliminating the presence of the coolant on the manufacturing part and delivers the heat–transferring fluid to the very cutting area of the tool. This paper provides a literature review on the closed–loop internally cooled cutting tools (CLICCT) for turning. The current level of knowledge and experimental machining with prototypes has proven that CLICCT can utilize the benefits of dry cooling, having a longer tool life.
... Previous studies have reported limitations in chip removal rates for uncoated carbide inserts, particularly at low cutting speeds (v c ) ranging from 20 to 60 m.min −1 when machining cobalt alloys [19][20][21][22]. Alternatively, researchers have explored higher cutting speeds, ranging from 60 to 400 m.min −1 , utilizing cutting tool types such as coated carbide, ceramic, or cBN tools [23][24][25][26][27][28][29]. However, high cutting speeds often reduce tool life, directly impacting cutting capacity and working time [24,29]. ...
The cobalt chromium molybdenum (Co-Cr-Mo) alloy is widely used in biomedical applications such as implants and prostheses. However, due to its inherent properties, machining this alloy is challenging. This study aims to analyze the effects of cutting parameters on tool wear and surface roughness during turning. A complete factorial experimental design was conducted with two factors, levels, and replicas, in which the cutting speed varied from 60 to 90 m.min⁻¹ and the feed rate from 0.08 to 0.13 mm.rev⁻¹. Tool wear was quantified using scanning electron microscopy (SEM) and confocal microscopy, while surface roughness was assessed using confocal microscopy. The results revealed the presence of crater and flank wear, with crater wear being predominant. The decrease in tool coating was found to have the most significant impact on the development of crater wear when adjusting feed rates. Additionally, changes in cutting parameters were shown to have a noteworthy effect on both the cutting tool’s wear and the workpiece surface’s roughness. Extreme cutting parameters resulted in significant differences in peak and valley heights on the turned workpiece surface, impacting the average roughness. Energy dispersion spectroscopy (EDXA) analysis identified the chemical elements on the worn tool and workpiece surfaces, revealing that the primary mechanism causing tool wear is workpiece material adhesion to the insert rake surface. Additionally, embedded carbides on the machined surface suggested abrasive action during cutting.
... The lowest roughness was obtained with the highest cutting speed. Bogajo et al., (2020), measured roughness and cutting forces using cryogenics. The cooling system was designed based on thermal analysis of the heat flow in the machining process. ...
Among the existing machining processes, turning and milling are characterized as the most used and consequently are considered the most important. Machining moves a market estimated at around 10% of gross national production. Many industrial components and parts are subjected to severe operating conditions, in corrosive environments, high temperatures what causes wear. With the development of industries, there is a need for steel alloys with different properties, to meet different purposes. Cobalt alloys, as well as others, arose from the need to develop metals that would meet the growing demand in applications with high temperatures and high working stress in gas turbine components. Due to their high mechanical and thermal resistance, these alloys are difficult to machining, a situation that requires in-depth studies to reduce process costs and improve the surface quality of machined parts. Machined surfaces may have different textures depending on the process. Turning and milling generate grooved profiles due to tool/part interaction. In many cases, roughness is used as an output parameter to control the process. Another important factor is the wear of cutting tools, which must be selected according to the material properties of the workpiece, machine tool and other parameters that influence its wear. Controlling the useful life of the tool is a decisive factor when you want to avoid loss of productivity, with fewer stops for changes, consequently, you have a more effective and economical production. The present study presents a brief review of the literature regarding turning and milling of cobalt alloys, regarding the optimization of machining parameters, tools used and the use of lubri-cooling techniques, with the objective of reducing the roughness of the parts, the tool wear, improve surface integrity and contribute to the sustainability of manufacturing processes when machining difficult-to-cut materials. In this review, a comparative analysis of the results is presented, indicating the gaps in research such as classification and processing of alloys, formation of carbides with non-uniform distribution, which impairs the performance of the tools. Some suggestions for future work indicate the absence of studies on the use of diamond and CBN tools, clarify the interaction medium lubricant-coolant-coating of the tools-alloy chemical composition and cutting parameters, in addition to dynamic analyzes in the cutting of hardened materials.
... In order to exploit the high specific heat capacity of water as heat absorbent in cutting magnesium alloy, internal cooling is a favorable approach as it avoids contact between water and magnesium. Bogajo et al. proposed an indirect cooling system whereby the cooling fluid flowed under the cutting zone [36]. The result of the study revealed a 12% improvement in surface roughness and a 12% reduction in cutting forces. ...
Magnesium alloys have broad applications, including medical implants and the aerospace sector owing to their great density and high strength-to-weight ratio. Dry cutting is a frequent technique for machining this material. However, it always leads to an excessive rise in temperature due to the absence of cooling at the cutting zone, which affects the machined surface integrity and chip morphology. In this study, chip morphology and surface integrity of the AZ31 magnesium alloy were investigated in the turning process using an internal cooling method called submerged convective cooling (SCC) to overcome the absence of cooling in dry cutting. This method can exploit the advantage of the high specific heat capacity of water as a cooling fluid without any reaction between water and magnesium to create a cooling element in the cutting zone. The chip morphologies and surface integrity were analyzed experimentally with varying cutting speeds under SCC and dry cutting. The experimental results revealed that SCC and dry cutting produced saw-tooth or serrated chip formation. The chips produced in dry cutting were continuous, while SCC was short and discontinuous as a result of a severe crack on the back surface of the chip. It was discovered that the grain refinement layer on the machined samples was thinner under SCC turning. SCC machining increased the microhardness of the AZ31 magnesium alloy by 60.5% from 55 HV to 88.3 HV, while dry turning exhibited a 49% increase in microhardness. The result revealed that surface roughness improved by 10.8%, 9.4% and 4.7% for cutting speeds (V) of 120, 180, and 240 m/min, respectively, under the SCC internal cooling. Based on the result obtained, SCC cutting outperformed dry cutting in terms of chip breakability, grain refinement, microhardness, and surface roughness.
... In cryogenic cooling, two clear different tool wear regions were observed that match with the force trends. On the one hand, below 300 m/min, homogenous tool wear was reported, and consequently, the cutting speed produces no significant variation in forces, as also observed by [19]. On the other hand, above 300 m/min, a drastic increase of tool wear was observed for the LN2 cooling conditions that produced the sudden increase of the forces. ...
Employing cutting fluids in machining processes, especially for difficult-to-cut materials, improves machinability through prolonged tool life, improves surface integrity and chip evacuation. However, like oil and water-based cutting fluids are hazardous to the environment and workers' health, alternative solutions are required. Liquid Nitrogen (LN2) is a cryogenic fluid that can be an option due to its low boiling point (-197ºC) and the fact it exists in the atmosphere at room conditions. Nevertheless, the feasibility of cryogenic cooling techniques in machining is not fully understood; this is why the Finite Element Method (FEM) could give an insight into the phenomena happening on the tool-chip/workpiece interface. This research aims to compare fundamental and industrial outputs when turning hardened steel 100Cr6 using Cubic Boron Nitride (CBN) inserts with wiper geometry in dry conditions and with cryogenic cooling. For this purpose, turning experimental tests were performed in both cooling conditions varying the cutting speed (150-550 m/min). Machining forces were measured during the tests, and then tool wear, microstructural damage, and residual stresses of the workpiece were characterised. A nose turning (3D) FEM model was also developed to understand the influence of cooling strategy on the outputs measured experimentally.
Cryogenic machining involves spraying cryogenic coolants to reduce the cutting tool temperature. In this study, cryogenic machining was applied to a titanium alloy with minimum quantity lubrication (MQL), and the tribological and machining performance were evaluated. As side-down milling was performed, the effects of cryogenic cooling and MQL were experimentally and numerically investigated with long machining distances (40, 000 mm), and the cutting force, tool wear, and tool temperature were analyzed. Compared to the wet condition, under the cryoMQL condition, which represents the simultaneous application of cryogenic cooling and MQL, the cutting force and flank wear length decreased by up to 17.7% and 46.4%, respectively. The cryogenically cooled and lubricated cutting tool enhanced the tribological performance, slowing tool wear. The reduced surface friction of the tool and tool wear decreased the frictional force and changed the trend of the cutting force according to the machining distance. The cryoMQL milling was simulated using DEFORM software. In the numerical study, a decrease in the tool temperature, which affects the reduction in cutting force and tool wear, was observed under cryoMQL conditions. The maximum tool temperature was reduced by 46.5% compared with that under wet conditions.
Cobalt chromium (CoCr) alloys find extensive use in medical applications due to their unique mechanical properties, such as high strength and low thermal conductivity. However, machining these alloys poses challenges as they are classified as hard-to-cut materials, leading to issues like short tool life, poor surface quality, and low productivity. Rapid tool wear is a significant problem when machining hard alloys, with cutting parameters, drill bit geometry, and types of cutting fluids being the main factors influencing tool wear. In this study, a series of experiments was conducted to investigate the influence of different cutting speeds and tool geometry on tool wear during micro drilling of CoCrMo. A flood cooling system was employed throughout the study, with a constant machining feed rate of 0.1 mm/rev. Three cutting tools with different point angles (118°, 130°, and 140°) and a diameter of 0.2 mm were utilized. The cutting speeds of 50 m/min, 65 m/min, and 80 m/min were varied. A total of 11 runs were performed, with each run consisting of drilling 30 holes. Forces, torques, and tool wear were measured after every subsequent 10 holes drilled. The results indicate that the combination of a 140° point angle and an 80 m/min cutting speed yielded the best performance, exhibiting the lowest force, torque, and tool wear values..
Superalloys are high-performance advanced materials specifically suitable for industrial applications at high as well as sub-zero temperatures. They are widely used in manufacturing components exposed to harsh working environments for prolonged durations undergoing non-uniform strains. Most superalloys possess a face-centred cubic microstructure, enabling them to exhibit significant creep resistance, corrosion resistance and thermo-mechanical fatigue even at elevated temperatures. However, these properties result in increased heat generation, increased tool wear and poor surface integrity, rendering them difficult-to-machine materials. Initially, dry machining was adopted as a tool for sustainable machining, but a few inherent characteristics, like high heat generation and large cutting forces limit its scope in superalloys machining. Subsequently, flood cooling was introduced to eliminate these problems. However, this strategy had an adverse effect on the environment and worker's health. Thus, the need for an alternate cooling technique complying with sustainable principles becomes essential. This review article focuses on the prerequisites for sustainable machining in general and superalloys machinability in particular. A thorough literature survey has been carried out focusing on the superalloys and their sustainable machining. From the present survey, it can be concluded that sustainable techniques such as minimum quantity lubrication, nanoparticles-based cooling, cryogenic cooling and hybrid cooling; are considered to be the alternate choices for machining superalloys which not only improve the machinability of superalloys but are also economical and eco-friendly. In the end, it can be concluded that such sustainable machining techniques have an ever-growing and ever-lasting scope, specifically in machining high-strength materials like superalloys.
Graphical abstract
Toward green manufacturing, the use of eco-friendly fluids such as cryogenic coolants is necessary for machining processes, instead of the use of conventional cutting fluids. The cryogenic spray method is most popular and, it can have high efficient for cooling cutting temperature and improving tool-life during machining operations. However, few studies have reported the benefits in terms of environment, cost for the cryogenic assisted hard turning processes. This study examines the economic and environmental impact of cryogenic cooling conditions on hard-turning machining. Liquid nitrogen was used as the cryogenic coolant. We examined the spray efficiency via computational fluid dynamics and experimental validation. The optimal nozzle for cryogenic spraying was found to have an internal angle of 45°. The nozzle of internal angle 45o has the highest distance and narrow width of spray shape in the results of computational fluid dynamics analysis and the experimental observation. Flank wear lengths were monitored under dry, wet, and cryogenic cooling conditions during the machining of AISI 52100 steel (62 HRC). The cryogenic assisted process improved ceramic cutting tool-life by 3–6 times compared to dry and wet conditions. The economic effects were also evaluated based on the tool-life data obtained. The improved tool life of the ceramic cutting tool by the cryogenic process reduced the total machine operation time; it thus reduced the electricity, carbon dioxide emissions of machine operations. The implementation of cryogenic cooling can be suitable for the green manufacturing process with the improvement of the environmental impact.
