High Pressure Coolant Research Articles

High Stock Removal Hard Turning of Hardened 52100 Steel with High-Pressure Coolant Applied

Hard turning experiments were conducted on hardened 52100 steel utilizing high-pressure (10.3 MPa) coolant. CBN inserts were used. The cutting conditions were investigated to obtain high stock removal with a feasible tool life on the large part hard turning process. A small thermocouple was mounted in a ground slot underneath the CBN insert tip, close to the cutting edge, to effectively measure the insert’s temperature during cutting. The cooling effect of the high-pressure coolant was evaluated by monitoring CBN insert crater wear and the time for the edge to become prematurely fractured. The temperature measurements show that the high-pressure coolant cools the insert more efficiently and has better lubrication capability leading to longer cut time without edge fracture. The study revealed that conventional low-pressure (0.4 MPa) coolant could not economically achieve high stock removal hard tuning due to high cutting temperature leading to premature fracture of the cutting edge. When using the high-pressure coolant and the optimized parameters, the tool life was enhanced by nearly 100%. The machined surface microstructure did not degrade even with the generation of very high shearing and friction heat energy in the cutting zone. Based on validation cut results and production part cycle assessment, the application of high-pressure coolant enables feasibility of high stock removal in hard turning with the ability to improve the productivity of large part rough stage turning by about 46%.

Effect of cutting parameters and high-pressure coolant on forces, surface roughness and tool life in turning AISI 1045 steel

Abstract The machining industries constantly look for novel techniques to decrease the forces generated in metal cutting, enhance the tool life and improve the surface quality. High-pressure coolant delivery is one such technique that is believed to enhance the overall machining process with its superior cooling capabilities. Hence, an investigation was made to compare the behavior of a turning tool in machining AISI 1045 steel material under conventional coolant (CC) and high-pressure coolant (HPC) conditions. The influence of applying coolant at high pressure on forces and surface finish was measured at various cutting speeds and feeds, and tool life analysis was performed at a constant cutting parameter. The study reveals that a 12–23% reduction in cutting force, a 17–27% reduction in feed force, and a 14–33% reduction in surface roughness values can be obtained when a high-pressure coolant is used. Besides, around 40% improvement in tool life was also seen. The capability of the coolant in the effective removal of heat from the tool-chip interface zone, decrease in frictional forces between the tool and work material, and superior chip breaking capabilities at high-pressure conditions are attributed to the performance improvement.

Batch Scheduling Algorithm with Approximation of Job Completion Times and Case Studies

Many small and medium-sized manufacturing companies process various product types to respond different customer orders in a single production line. To improve their productivity, they often apply batch processing while considering various product types, constraints on batch sizes and setups, and due date of each order. This study introduces a batch scheduling heuristic for a production line with multiple product types and different due dates of each order. As the process times vary due to the different batch sizes and product types, a recursive equation is developed based on a flow line model to obtain the upper bound on the completion times with less computational complexity than full computation. The batch scheduling algorithm combines and schedules the orders with same product types into a batch to improve productivity, but within the constraints to match the due dates of the orders. The algorithm incorporates simple and intuitive principles for the purpose of being applied to small and medium companies. To test the algorithm, two case studies are introduced; a high pressure coolant (HPC) manufacturing line and a press process at a plate-type heat exchanger manufacturer. From the case studies, the developed algorithm provides significant improvements in setup frequency and thus convenience of workers and productivity, without violating due dates of each order.

High Speed Machining of Inconel 718 with High Pressure Coolant Focusing on Material Structures of CBN Tools

Recently, cubic boron nitride (CBN) cutting tools and high pressure coolant (HPC) have garnered significant attention for high performance machining of difficult-to-cut materials, such as nickel-based super alloy, Inconel 718. In this study, the cutting performance of a low-CBN-content (L-CBN) cutting tool, which is known as a suitable CBN material structure for the high-speed machining of Inconel 718, is investigated under the HPC conditions. The experimetntal results show that, although crater wear is significantly suppressed as the coolant pressure increases, the combination of high cutting speed and high pressure coolant causes severe thermal cracking on the tool rake face of the L-CBN cutting tool. Hence, we evaluate the cutting performance of high-CBN-content (H-CBN) cutting tool which has smaller coefficcient of thermal expansion, compared with the L-CBN cutting tool. A series of cutting experiments shows that changing the material structure of the CBN tool effectively suppressed thermal cracking and that the H-CBN tool is a highly promising option for the high performance machining of Inconel 718.

A machinability evaluation based on the thermal and mechanical properties of two engine valve steels

Iron-based superalloys are difficult to machine because of their thermal and mechanical properties provided by alloying elements as nickel, chromium, titanium, and aluminum. However, parts made with this kind of material has to be machined during their production processes. In this work, two different automotive engine valve steel grades, VAT 30® and VAT 36®, were compared in terms of machinability, considering cutting power consumption, roughness of the machined surface, and tool life, besides the identification of the main tool wear mechanisms that have led to the end of tool life. The main goal of this work is to understand the difference in these machining outputs based on the thermal and mechanical properties of these two materials. In order to reach this goal, turning tests were held using two different cooling conditions, conventional and high-pressure coolant. Also, two PVD-coated carbide inserts were applied, one with negative rake angle and another neutral. Finally, cutting speed was tested in two levels, providing a full 24 factorial planning. Results show that VAT 30® has shown higher machinability in terms of tool life in almost every condition, although this steel presents higher hardness, mechanical strength, and strain hardening coefficient, besides lower thermal conductivity. However, it also presents lower ductility and abrasiveness, features that retarded abrasion and attrition as tool wear mechanisms, in such a way that tool life could have been lengthened.

On the machinability of the Ni-30 high-temperature iron-based superalloy

Superalloys are high-performance materials which combine high tensile, creep and fatigue strength, besides good ductility, toughness and resistance to corrosion, properties that are also responsible for their low machinability. The VAT 30® alloy contains an austenitic stainless steel base with additions of chromium, nickel, titanium and aluminum, and it is mainly applied on the manufacture of valves of combustion engines, due to its advantageous characteristics. This alloy exhibits both high ductility and abrasiveness, features that may promote both attrition and abrasion wear mechanisms on the tool used to cut it. This work contains some investigations about the effect of cooling condition, tool rake angle and cutting speed on the machinability of Ni-30 alloy in terms of cutting power consumption, surface roughness and tool life, besides the tool wear mechanisms. Conventional and high-pressure coolant injected toward the tool rake face was compared, as well as negative rake angle and neutral tooling, besides two different cutting speeds. Results show that high-pressure coolant may reduce cutting power consumption and even increase the volume of material removed during tool life up to 45% in some cases, but this same influence has not been verified regarding the workpiece arithmetical mean roughness value. Negative and neutral rake angle tools did not present very different results in terms of power and roughness, but negative tools provided considerably higher volume of material removed per tool life (up to 75% in one condition). Cutting speed showed strong effect on the cutting power, as expected, but no reasonable effect on workpiece surface roughness; regarding tool life, the cutting speed increase typically reduced the volume of material removed per tool life with conventional cooling, but when high-pressure coolant was used, this effect was attenuated. Abrasion and attrition were the main tool wear mechanisms in any tested condition.

Experimental investigations on surface integrity and chip morphology in hard tuning of AISI D3 steel under sustainable nanofluid-based minimum quantity lubrication

Efficient cooling and lubrication techniques are required to obtain sustainable machining of difficult-to-cut materials, which are the pillars of aerospace, automotive, medical and nuclear industries. Excessive cutting fluid is required and consumed in machining difficult-to-machine materials with high-pressure coolant supplies. Nanofluid-assisted minimum quantity lubrication (NFMQL) is adorned with improved machining performance and environmental sustainability. The present work addresses the surface integrity and chip morphology in finish hard turning of AISI D3 steel under NFMQL condition. The surface integrity aspects include microhardness, residual stress, white layer formation, machined surface morphology, and surface roughness. This experimental investigation aims to explore the feasibility of low-cost multilayer (TiCN/Al2O3/TiN) coated carbide tool in hard machining applications and to assess the propitious role of minimum quantity lubrication using graphene nanoparticles with enriched radiator coolant-based nano-cutting fluid for machinability improvement in hardened steel. Combined approach of central composite design—analysis of variance, desirability function analysis, and response surface methodology, has been subsequently employed for experimental investigation, predictive modelling, and optimization of surface roughness. With a motivational philosophy of “Go Green-Think Green-Act Green”, the work also deals with economic analysis and sustainability assessment under environmental-friendly NFMQL condition. It is expected that the found optimized parameters can contribute to machining end-outcomes such as an improved surface finish and reduced machining cost. The results showed that machining with NFMQL provided an effective cooling–lubrication strategy, safer and cleaner production, environmental friendliness and assisted in improving sustainability. In conclusion, the proposed NFMQL turning strategy is a robust method validated by statistical analysis for large industrial applications, especially in mould and die making sectors.

Investigation on Machined Surface Quality During Cutting of GH4169 Under High-Pressure Cooling

The aerospace component material GH4169 has low thermal conductivity and poor machinability, resulting in difficulty to guarantee good surface quality after conventional cutting. High-pressure cooling assisted machining technology can effectively improve the problem. In order to study the effect of high-pressure cooling assisted processing technology on the machined surface quality of GH4169, in this paper, Deform-3D was first used to construct a thermo-mechanical coupling finite element model for turning GH4169 under high-pressure cooling conditions, to analyze the turning temperature and surface residual stress. Then, analysis was carried out on the residual stress, work hardening behavior, and metamorphic layer of the GH4169 machined surface, in combination with the turning experiment. The results show that, under the conditions of little feeding and highspeed cutting, the GH4169 turning surface generates residual tensile stress along with both the feeding and turning directions. Moreover, the residual tensile stress gradually turns into the residual compressive stress along the depth direction. The application of high-pressure coolant can reduce the residual tensile stress of the machined surface. As the cooling pressure increases, the residual tensile stress of the machined surface decreases. The coupling effect between thermal deformation and plastic deformation when turning GH4169 can cause the work hardening of the surface, and the hardening degree decreases with the increase of cooling pressure. The high-pressure cooling assisted machining technology can effectively reduce surface plastic deformation, and promote the lessening of grain refinement degree of the material surface, thereby reducing the thickness of the metamorphic layer.

Influence of cutting fluid flow on tool wear in high-pressure coolant turning using a novel internally cooled insert

The knowledge of this research is established on the newly proposed internally cooled tool having the cooling channel make inside the insert. In the high pressure coolant turning, the differential pressure caused by the hydraulic pressure at the flank wedge and atmosphere pressure at each end of cooling channel is able to advance the cutting heat dissipation by enhanced flow. This paper focus on the relation between tool wear and cutting fluid flows produced by cooling channels having different angular positions. Computational fluid dynamics analysis based on the three-dimension turbulent model was used to simulate the flow streamline to clarify the cooling ability, followed by the experimental verification in the high pressure jet assistance turning of Inconel 718. As a result, applying cooling channel was proved can prolong tool life by about 40% most and received an advanced surface quality even the critical pressure was reached. The cooling channel made near to the cutting notch and major flank significantly suppressed the notch wear and flank wear, respectively.

Reduction of Power Consumption by Chip Breakability Control in Ti6Al4V Titanium Alloy Turning.

The paper concerns the problem of energy savings in turning of titanium alloy Ti6Al4V. Since this alloy belongs to difficult to cut materials, there is a problem with chip forming and breaking. The turning process is often supported by implementing a high-pressure cooling (HPC) system. Based on the observations and the adopted chip classification method, the authors proved that it is not necessary to use this method in roughing operations, however it helps with the chips breaking process in finishing operations. A general algorithm for machining optimization due to the chip geometry is presented and described. In the presented case, it was shown that the acceptable chip geometry could be obtained with a reduced power consumption by approximately Pc = 0.5 kW. The authors concluded that it was not necessary to apply cutting data and a coolant system to achieve perfect chip geometry. An acceptable form was often sufficient, while requiring less energy. An additional factor resulting from the operation of systems supporting the cutting process, such as an HPC device, should be taken into account in the formula concerning the energy consumption (EC) of a computerized numerical control (CNC) machine tool.

Simultaneous optimization of output parameters in HPC drilling using multi response optimization technique with desirability function approach

PurposeThis paper aims to examine an investigation of high-pressure coolant (HPC) drilling process with regard to experimental models of output parameters, effect of input parameters on output parameters and simultaneous optimization of the output parameters.Design/methodology/approachExperimental plan was designed using response surface method and experiments were conducted on HPC drilling set up. Measurements for output parameters were carried out and mathematical models were obtained. Multi response optimization using a composite desirability function approach was used to obtain optimum values of input parameters for simultaneous optimization of output parameters.FindingsOptimal value of input parameters for optimization of HPC drilling process were obtained as; coolant pressure: 21 bar, spindle speed: 3,970 rpm, feed rate: 0.084 mm/rev and peck depth: 5.50 mm. The composite desirability obtained is 0.9412, which indicates that the performance of HPC drilling process was significantly optimized. Developed mathematical models of the output parameters accurately represent the entire design space under investigation.Originality/valueThis is the first study that involves variation of higher coolant pressure and investigation of HPC drilling process using response surface methodology and multi response optimization technique with desirability function.

Experimental Study on Tool Wear in Cutting Superalloy under High-Pressure Cooling

Superalloy is widely used in the aerospace industry and is a typical difficult-to-cut material. PCBN tool has good cutting efficiency in processing superalloy, but it has a larger cutting force, higher cutting temperature and severe tool wear in the cutting process. High-pressure cooling has great advantages in processing high strength steels such as superalloy, which can effectively reduce cutting temperature and improve tool-chip breaking performance, thereby reducing tool wear. Therefore, it is of theoretical significance and practical value to study tool wear mechanism of PCBN tool cutting superalloy under high-pressure cooling. Firstly, the wear form of the flank is analyzed to provide theoretical support for tool wear research; Secondly, the experimental study of tool wear under high-pressure cooling is carried out. The tool wear under different cutting time, cutting speed and cooling pressure is analyzed respectively, and the influence rule of different cutting conditions on tool wear is obtained; Finally, a tool wear prediction model under high-pressure cooling is established to provide theoretical basis and technical methods for efficient processing of superalloy and optimization of cutting parameters under high-pressure cooling.

Experimental Research on Turning of Superalloy GH4169 under High Pressure Cooling Condition

Superalloy GH4169 possesses excellent high temperature strength, thermal stability, and thermal fatigue, and is widely used in aerospace and other fields. However, it is a typical difficult-to-cut material owing to its poor thermal conductivity, high plastic toughness, severe workpiece hardening, and difficult chip breaking. In this study, high pressure cooling was used for GH4169 cutting test. The effects of high pressure cooling on the cutting force, chip morphology, and tool wear were analyzed, which can provide technical support to achieve high efficiency turning of GH4169.

Coolant boiling and cavitation wear – a new tool wear mechanism on WC tools in machining Alloy 718 with high-pressure coolant

In recent years, research interest in liquid coolant media applied to the tool–workpiece interface (the tertiary shear zone) has grown considerably. In particular, attention has increased for work where the media has been applied under high-pressure. This is most likely triggered by the positive results reported on similar applications, but with coolant media directed towards the rake face of the cutting tool (the secondary shear zone). The most typical applications have not surprisingly been related to the machining of Heat Resistant Super Alloys (HRSA) or other “difficult to machine” alloys where the main intention has been to extend tool life and improve surface finish through reduced shear zone temperatures.Concurrently, these achievements have revealed a knowledge gap and unlocked a new research area in understanding the effects and influences of coolant media applied on super-heated surfaces under high-pressure conditions. The aim of this study is to investigate the “coolant boiling and cavitation” phenomena that emerges during the application of coolant under high-pressure to the flank face of an uncoated WC tool while turning Alloy 718. The experimental campaign was conducted in three aspects: varying flank (coolant media) pressure; varying spiral cutting length (SCL); and varying cutting speed.The results revealed that the location and size of the coolant-boiling region correlated with flank wear, coolant pressure and vapour pressure of the coolant at the investigated pressure levels. Further, the results showed that coolant applied with a lower pressure than the vapour pressure of the coolant itself caused the “Leidenfrost” effect. This then acts as a coolant media barrier and effectively reduces the heat transport from the cutting zone.Further, erosion pits were observed on small areas of the cutting tool, resembling the typical signs of cavitation (usually found in much different applications such as pumps and propellers). The discovered wear mechanism denoted as “Cavitation Wear” was used as base for the discussion aimed to deepen the understanding of the conditions close to the sliding interface between the tool and the workpiece. Even though “Cavitation Wear” has been widely reported in hydraulic systems like pumps and water turbines, it is a new phenomenon to be seen on cutting tools while using high-pressure flank cooling.

High-Speed Rotary Ultrasonic Elliptical Milling of Ti-6Al-4V Using High-Pressure Coolant

High-speed rotary ultrasonic elliptical milling (HRUEM), as a novel ultrasonic vibration cutting method, has been introduced in milling the alloy Ti-6Al-4V. The application of ultrasonic vibration in high-speed milling can help open the cutting contact area intermittently. New cutting effects will happen with full use of the separation effect brought by ultrasonic vibration and the cooling effect brought by a high-pressure coolant (HPC). On the basis of that, this paper firstly introduces HPC into HRUEM of Ti-6Al-4V in the open literature and analyzes the tool-workpiece separation cooling mechanism in HRUEM, including kinematic analysis of tool tip trajectories, tool-workpiece separation principles and high-pressure coolant effects. We have conducted a comprehensive experimental study and the results show when HPC is increased to 200 bar, compared to conventional milling (CM), the tool life in HUREM can be extended by 6.6 times at 80 m/min, 4.2 times at 120 m/min and 2.4 times at 160 m/min. The maximum material removal volume (MRV) for a given new end mill in HRUEM is increased by 657% approximately. When the cutting speed is 80 m/min, the cutting temperature of the workpiece in HRUEM is reduced by 24.1% compared to that of CM. By applying the combination of HPC and tool-workpiece periodic separation, we can significantly enhance the cooling and lubrication efficiency in HRUEM and also inhibit the tool wear mode of adhesive wear typically occurred in CM.

Effect of Process Parameters on Surface Roughness in HPC Drilling of AISI 1055 Steel

Data regarding the influence of high-pressure coolant on the performance of drilling process using design of experiment has been limitedly available. This paper presents the effect of higher coolant pressures along with spindle speed, feed rate and peck depth on the surface roughness of hole using Taguchi technique. Experimental set up was developed consisting of specially manufactured high-pressure coolant system and high-pressure adapter assembly attached to vertical machining center. Developed experimental set up has optimized utilization of non-through coolant vertical machining center in a small-scale industry. Experiments were conducted on AISI 1055 steel with TiAIN coated drill on the vertical machining center. Taguchi technique was used for design of experiment and analysis of results. Results revealed that the surface roughness improve till coolant pressure reaches to an optimum value of 13.5 bar and there after it decreases. Coolant pressure and spindle speed was the significant process parameters for the hole surface roughness. Surface roughness at the top of hole was considerably lower than the bottom of hole, under the action of all process parameters. Supply of coolant at high pressure has resulted in lower surface roughness even with large peck depth; which indicate that, manufacturing cost can be reduced with the use of high-pressure coolant in drilling.

FEM Simulation and Experiment of High-Pressure Cooling Effect on Cutting Force and Machined Surface Quality During Turning Inconel 718

High-pressure jet coolant assistance was used in the cutting process of Inconel 718. The effects of coolant pressure on cutting force and machined surface quality were researched. As well as the experimental design, Two-dimensional cutting models for Inconel 718 were established using AdvantEdge FEM software. Simulations and experiments were carried out based on the Taguchi method. The simulation predictions and experimental test results were compared. The influence of variables on cutting force and machined surface roughness was determined by variance analysis. The effect of cooling pressure on roughness of machined surfaces was studied by simulation and experiment tests.

Chip Breakability in Turning of 7075 Aluminium Alloy with a High-Pressure Coolant Supply

Because of its extremely high strength to weight ratio, 7075 aluminum alloy is used for highly stressed structural parts including aircraft fittings, gears and shafts and various other commercial aircraft, aerospace and transportation equipment. In the case of cutting aluminum alloys, the chip breakability is the most important feature to ensure reliable operation in automated machining. In this study, in turning of 7075 aluminum alloy with a high-pressure coolant supply, the chip configurations, and the mass and thickness of chips were experimentally investigated. The following results were obtained:(1) In the case of a cutting speed of 5.0 m/s, a feed rate from 0.05 mm/rev to 0.50 mm/rev and a depth of cut from 0.1 mm to 3.0 mm, chips were not broken at a feed rate of 0.15 mm/rev or less with the conventional coolant supply. With a high-pressure coolant supply, the combination area of feed rate and depth of cut in which chips were broken was wider than that with the conventional coolant supply. With the high-pressure coolant supply at a coolant pressure of 7 MPa, there was a combination area of feed rate and depth of cut in which chips were not broken. However, chips were broken in all areas at a coolant pressure of 20 MPa.(2) In the case of both the high-pressure coolant supply, which has a coolant pressure of 7, 14 or 20 MPa, and the conventional coolant supply, the thickness of chip increased with the increase of the depth of cut. And, the thickness of chip did not change depending on the cutting method, namely the high-pressure coolant supply cutting method and the conventional coolant supply cutting method.

Predictive modeling of turning operations under different cooling/lubricating conditions for sustainable manufacturing with machine learning techniques

Sustainable manufacturing is one of the most important and most challenging issues in present industrial scenario. With the intention of diminish negative effects associated with cutting fluids, the machining industries are continuously developing technologies and systems for cooling/lubricating of the cutting zone while maintaining machining efficiency. In the present study, three regression based machine learning techniques, namely, polynomial regression (PR), support vector regression (SVR) and Gaussian process regression (GPR) were developed to predict machining force, cutting power and cutting pressure in the turning of AISI 1045. In the development of predictive models, machining parameters of cutting speed, depth of cut and feed rate were considered as control factors. Since cooling/lubricating techniques significantly affects the machining performance, prediction model development of quality characteristics was performed under minimum quantity lubrication (MQL) and high-pressure coolant (HPC) cutting conditions. The prediction accuracy of developed models was evaluated by statistical error analyzing methods. Results of regressions based machine learning techniques were also compared with probably one of the most frequently used machine learning method, namely artificial neural networks (ANN). Finally, a metaheuristic approach based on a neural network algorithm was utilized to perform an efficient multi-objective optimization of process parameters for both cutting environment.

Advanced heavy water reactor control with the aid of adaptive second-order sliding mode controller

PurposeAdvanced heavy water reactor (AHWR) is a pressure tube type of heavy water reactor. It eliminates high-pressure heavy water coolant resulting in a reduction of heavy water leakage losses and eliminating heavy water recovery system. It recovers the heat generated in the moderator for feed water heating. However, it requires a satisfactory technological response to develop an effective controller that attains the challenges of the very high-level safety system. Hence, they require application-specific improvement for better controlling performance.Design/methodology/approachThe purpose of this study intends to propose a system for controlling state vectors v1 and v2and in AHWR using Grey Wolf second-order sliding mode control (GW-SoSMC) technique. The main aim of the paper is to minimize the errors between the predicted and desired azimuthal angles of the system. With this proposed method, it is possible to mitigate both the chattering phenomenon and controlling performance of AHWR system. It implements a SoSMC controller based on GWO algorithm for the purpose of controlling the state vectors in the AHWR system. It aims to accomplish a controller for improving the performance of the AHWR system.FindingsThrough the performance analysis, the efficiency of the proposed GW-SoSMC technique was verified by comparing it with various conventional algorithms, such as GW-SMC, FF-SoSMC, ABC-SoSMC, GS-SoSMC and GA-SoSMC. From the analysis, it was obtained that the implemented GW-SoSMC technique was 65.3 per cent superior to GW-SMC, 65.32 per cent superior to both FF-SoSMC and 65 per cent superior to ABC-SoSMC, 65.8 per cent superior to the GS-SoSMC and 58 per cent superior to the GA-SoSMC methods. Thus, the effectiveness of the proposed method in controlling the state vectors in AHWR was obtained.Originality/valueThis paper presents a technique for controlling the state vectors in the AHWR system using GWO algorithm. This is the first work that uses GWO-based optimization for controlling state vectors in the AHWR system.