Tool-work Thermocouple Research Articles

Полуэмпирическое моделирование температуры резания и шероховатости поверхности при точении конструкционных материалов твердосплавным инструментом с покрытием TiAlN

Introduction. In manufacturing, obtaining a specified surface roughness of the machined components is of great importance to fulfill functional requirements. However, this is significantly affected by the heat generated during processing, potentially causing variations in dimensional accuracy. The surface roughness significantly affects the fatigue performance of the component, while the cutting tool's lifespan is dictated by the generation of cutting temperatures. The purpose of the study is to create semi-empirical models for predicting surface roughness and temperature of different work materials. Improved cutting performance is achieved by precisely determining the cutting temperature in the zone being machined. However, calculating the cutting temperature for each specific case is fraught with difficulties in terms of labor resources and financial investments. This paper presents a comprehensive empirical formula designed to predict both theoretical temperature and surface roughness. The methodology. The surface roughness and temperature values were evaluated for EN 8, Al 380, SS 316 and SAE 8620 materials using TiAlN coated carbide tool. The TiAlN coating was formed using Physical Vapor Deposition (PVD) Technique. The response surface methodology was used to prepare predictive models. Cutting speed (140 to 340 m/min), feed (0.08 to 0.24 mm/rev) and depth of cut (0.6 to 1.0 mm) was used as input parameters for measuring the performance of all material in terms of surface roughness and cutting temperature. The tool-work thermocouple principle was used to measure the temperature at the chip-tool interface. A Novel Calibration Setup was developed to establish a connection between the electromotive force (EMF) generated during machining and the cutting temperature. Results and Discussion. It is observed that the power required for machining was largely transformed into heat. The highest cutting temperature is recorded when machining of SS 316 followed by SAE 8620, EN 8. However, low temperature is reported during machining of Al 380 and it is mainly governed by the thermal conductivity of the material. The lowest surface roughness is observed in SAE 8620, EN 8 material followed by SS 316 and Al 380. Semi-empirical method and regression model equations show a good agreement with each other. Statistical analysis of nonlinear estimation reveals that the cutting speed, feed, and density of the material have a greater effect on surface roughness, whereas the depth of cut has a greater effect on temperature generation. The study will be very useful for predicting industrial productivity when machining of EN 8, Al 380, SS 316 and SAE 8620 materials with TiAlN-coated carbide tool.

Turning characteristics of titanium alloy Ti-6Al-4V with high-pressure cutting fluid

This study investigates the effect of high-pressure cutting fluid on the turning characteristics of Ti-6Al-4V alloy. A noncoated carbide tool was used to measure the cutting temperature using a tool-work thermocouple technique, and the cutting characteristics were evaluated with respect to the cutting temperature, chip breakability, and tool wear. Furthermore, the viability of TiAlN/AlCr2O3-coated tool was examined. The coolant jet when placed towards the cutting zone on the rake face is effective in reducing the cutting temperature because of the reduction in the chip-tool contact length. Based on this result, tools with a textured rake face were examined.

Analysis of cutting temperature during turning of SS 304 using uncoated and PVD coated carbide inserts

Cutting temperature is one of the most important parameters controlling the tool wear and consequently the life duration and other parameters of the machined surface. Hence, it would be essential to do tool temperature measurements during machining tests. To understand the physical phenomena of temperature generated during cutting processes, especially in the machining of difficult-to-cut materials, the characterization of the temperature field is essential. In the present paper, an attempt is made to determine the tool-chip interface temperature using an experimental approach during the turning of SS 304 material. It is considered to be difficult to cut material due to its properties like low thermal conductivity, and work hardening. The application of tool-work thermocouple method is used for the experimental approach whereas the empirical model is prepared and validated based on experimental results. Cutting tests were carried out on SS 304 work material by using uncoated (K-313 grade) and TiAlN PVD coated (KC 5525) cemented carbide insert at the cutting speed of 140–260 m/min and feed of 0.08–0.20 mm/rev, keeping the depth of cut constant as 1 mm. Experimental observations indicate that temperatures generated during machining are strongly dependent on the cutting speed. The high temperature was observed during turning using TiAlN Coated tools. However, due to the better thermal stability of the coating, the coated tool performs 10–12 % more than the uncoated tool.

Теория размерностей и моделирование температуры на границе раздела стружка–инструмент при точении SS304 на основе искусственных нейронных сетей

Introduction. During machining, the resulting temperature has a wider and more critical impact on machining performance. During machining, the power consumption is mainly converted into heat near the cutting edge of the tool. Almost all the work performed during plastic deformation turns into heat. Researchers have put a lot of effort into measuring the cutting temperature during machining, as it significantly affects tool life and overall machining performance. The purpose of the work: to investigate the temperature of the chip-tool interface, taking into account the influence of cutting parameters and the type of tool coating during SS304 turning. The chip-tool interface temperature is measured by changing the cutting speed and feed with a constant cutting depth for uncoated and PVD single-layer TiAlN and multi-layer TiN/TiAlN coated carbide tools. In addition, an attempt is made to develop a model for predicting the temperature of the chip-tool interface using dimensional analysis and ANN simulating to better understand the process. The methods of investigation. Experiments are carried out with varying the cutting speed (140-260 m/min), feed (0.08-0.2 mm/rev) and a constant cutting depth of 1 mm. The chip-tool interface temperature is measured using the tool-work thermocouple principle. The Calibration Setup is designed to establish the relationship between the produced electromotive force (EMF) and the cutting temperature during machining. Statistical dimensional analysis and artificial neural network models have been developed to predict the temperature of the chip-tool interface. Tangential cutting force and chip attributes such as chip width and thickness are also measured depending on the cutting conditions, which is a prerequisite for dimensional analysis simulation. Results and Discussion. A tool made of TiAlN carbide with PVD coating had a lower temperature at the chip-tool interface than a tool with TiN/TiAlN coating. It has been observed that the chip-tool interface temperature increases prominently with the cutting speed, followed by the chip cross-sectional area and the specific cutting pressure. However, a lower cutting force was observed when using a carbide tool with a multi-layer TiN/TiAlN coating, which can be attributed to a lower coefficient of friction created by the front surface of this tool for flowing chips. On the other hand, the greatest cutting force was observed in uncoated carbide tools. It was noticed that the developed models allow predicting the temperature of the chip-tool interface with an absolute error of 5%. However, the lowest average absolute error of 0.78% was observed with the ANN model and, therefore, can be reliably used to predict the chip-tool interface temperature during SS304 turning.

Measurement, modelling and optimization of the average temperature at the tool work interface for turning of AISI 1040 steel using ANN-GA methodology

Due to the mechanical properties and machinability of AISI 1040 steel, it has a broad range of industrial applicability. The present work investigates the dependence of the average temperature generated at the tool work interface on machining parameters such as cutting speed, feed rate and depth of cut. The machining parameters were varied at three equally spaced levels. Experiments were carried out following combinations in Taguchi’s L27 orthogonal array. A simple and cost-effective tool work thermocouple was devised and calibrated to obtain the tool work interface temperature. A 3-5-1 feed forward artificial neural network (ANN) model trained using the Levenberg-Marquardt (LM) back propagation algorithm resulted in efficient modelling of the complex relationship between the average cutting temperature and machining parameters (R-value of 0.99). The trained network was optimized using genetic algorithm (GA) to predict optimal turning parameters. This methodology has been termed as ANN-GA method. A significant reduction in the average cutting temperature could be realized due to optimization using ANN-GA method. Analysis of variance revealed highest contribution from the cutting speed and its square term in controlling the cutting temperature at tool work interface.

Cutting temperature measurement in turning of thermoplastic composites using a tool-work thermocouple

Turning of carbon fibre reinforced thermoplastic pipes is used for production of fluid ducts for the aerospace and oil industries. Although thermoplastics are chemically stable, the matrix could be affected by the heat introduced by the machining process. This paper presents how to measure cutting temperature using C/PEEK and C/PA12 material as examples. A suitable method based on a thermocouple circuit and electric conductivity of the carbon fibres is presented, including system calibration. Measurement uncertainties were established for this new method of calibration and measurement for both tested materials. The cutting temperature measurements were analysed by ANOVA and significant factors and its dependence on temperature were identified for further machining process optimization and determination of the predictive model equation. This mathematical cutting temperature model was estimated based on the measurements, and empirical coefficients were identified for selected statistically significant parameters for both composite materials. Because the measured temperatures were above the melting point, the machined surface, chips and structural changes of polymeric matrices were measured in order to prove heat affection.

A comparative study on the machining characteristics on turning AISI 52100 alloy steel in dry and microlubrication condition

ABSTRACT This paper elucidates the outcome of machining factors specifically cutting velocity, feed rate and depth of cut on the machining characteristics such as surface roughness and tool-work interface temperature while turning cylindrical AISI 52100 steel alloy components in dry and microlubrication machining conditions. The experiments are designed based on the Taguchi’s L25(53) orthogonal array and conducted on an All Geared Lathe, simultaneously the tool-work interface temperature was observed using a K-type tool-work thermocouple and subsequently, a mathematical model was developed for the tool-work interface temperature values through regression analysis. The surface roughness of the turned steel alloy components is deliberated by means of a precise surface roughness apparatus. A prediction model in lieu of average surface roughness is created by means of nonlinear regression examination with the aid of MINITAB software. The most favourable machining settings are recognised by Taguchi’s method and verified with a confirmation trial. The results revealed that machining under microlubrication condition exhibited lesser temperature at the tool-work interface and the quality of the machined components also exhibits lesser roughness when compared with components of dry machining condition.

Turning operation of AISI 4340 steel in flooded, near-dry and dry conditions: a comparative study on tool-work interface temperature

Abstract The objective of this study is to analyse the effect of tool-work interface temperature observed during the turning of AISI 4340 cylindrical steel components in three machining conditions, namely flooded, near-dry and dry conditions with three separate CNMG-PEF 800 diamond finish Titanium Nitride (TiN) coated carbide cutting tool. The machining parameters considered in this study are cutting velocity, feed rate and depth of cut. The experiments were planned based on full factorial design (33) and executed in an All Geared Conventional Lathe. The tool-work interface temperature was observed using a K-type tool-work thermocouple, while the machining of steel, and subsequently, a mathematical model was developed for the tool-work interface temperature values through regression analysis. The significance of the selected machining parameters and their levels on tool-work interface temperature was found using analysis of variance (ANOVA) and F-test. The results revealed that machining under near-dry condition exhibited lesser temperature at the tool-work interface, which is the sign of producing better quality products in equivalence with the machining under flooded condition.

Using the temperature method for the prediction of tool life in sustainable production

The tool workpiece-type thermocouple is practical, inexpensive and provides an indication of temperature trends in the tool-chip-workpiece interface. These temperatures also correlate with tool wear. Using this sensor system, a novel method for predicting functional lifetime in tool parts has been developed. In this paper, an extended Taylor's functional relationship was determined based on measurements of the tool work temperature. This method allows prediction of tool life based on a tool-work thermocouple temperature with a few traditional tool-wear experiments. To confirm the reliability of the proposed temperature-based method of tool-life prediction, the traditional tool-life testing methods are applied using standard experimental procedures for exploring tool-to-surface responses.

Precise Evaluation of Cutting Temperature in Milling Process by Tool-Work Thermocouple Method

Precise Evaluation of Cutting Temperature in Milling Process by Tool-Work Thermocouple Method

Cooling performance of micro-texture at the tool flank face under high pressure jet coolant assistance

Micro-texture at the tool face is a state-of-the-art technique to improve cutting performance. In this paper, five types of micro-texture were fabricated at the flank face to improve the cooling performance under the condition of high pressure jet coolant assistance. By using micro-textures consisted of pin fins, plate fins and pits fabricated 0.3mm away from the cutting edge, heat transfer from the tool face to coolant was enhanced. The conditions of tool wear, adhesion and chip formation were compared between the micro-textured and non-patterned tools in the longitudinal turning of the nickel-based superalloy Inconel 718. As a result, micro-textured tools always exhibited the reduced flank and crater wear compared with the non-patterned tool, and the rate of tool wear was influenced by the array and height of fin. The energy dispersive spectroscopy analysis of worn flank faces and the electromotive forces obtained from the tool-work thermocouple supported better cooling performances of micro-textured tools. In addition, coolant deposition at flank face evidenced that heat transfer could be promoted by micro-texture near the border of the contact area between the flank wear land and machined surface. Finally, the changes of flow patterns with pit depth are analyzed for pit type tools by computational fluid dynamics. This investigation clearly showed the function of micro-textures for increasing the turbulent kinetic energy and cooling the textured tool face.

High-pressure coolant on flank and rake surfaces of tool in turning of Ti-6Al-4V: investigations on forces, temperature, and chips

An experimental investigation has been performed in turning of Ti-6Al-4V by using coated carbide tool employed under dry condition and pressurized coolant at the flank and rake surfaces concurrently. To impinge coolant in this manner, customized nozzle was designed and fabricated. As part of the study, the cutting force, feed force, cutting temperature, and chip characteristics were explored as quality indices at varied speed and feed. To do so, the cutting forces and temperature were measured by using a robust 3D dynamometer and tool-work thermocouple, respectively. Apart from experimental investigation, the role of each factor was quantified by the statistical analysis of variance; consequently, it was revealed that the high-pressure coolant exerted a significant impact on all the responses. Results showed that the effective cooling and lubrication were achieved by the coolant jets; this reduced the cutting forces and temperature. In addition, the shortened chip-tool contact length and jet activated wedge effect contributed to the improved machining performance. Nevertheless, the chip breakability was not favorable which can be attributed to the low pressure of the supplied coolant.

Response surface and neural network based predictive models of cutting temperature in hard turning

The present study aimed to develop the predictive models of average tool-workpiece interface temperature in hard turning of AISI 1060 steels by coated carbide insert. The Response Surface Methodology (RSM) and Artificial Neural Network (ANN) were employed to predict the temperature in respect of cutting speed, feed rate and material hardness. The number and orientation of the experimental trials, conducted in both dry and high pressure coolant (HPC) environments, were planned using full factorial design. The temperature was measured by using the tool-work thermocouple. In RSM model, two quadratic equations of temperature were derived from experimental data. The analysis of variance (ANOVA) and mean absolute percentage error (MAPE) were performed to suffice the adequacy of the models. In ANN model, 80% data were used to train and 20% data were employed for testing. Like RSM, herein, the error analysis was also conducted. The accuracy of the RSM and ANN model was found to be ⩾99%. The ANN models exhibit an error of ∼5% MAE for testing data. The regression coefficient was found to be greater than 99.9% for both dry and HPC. Both these models are acceptable, although the ANN model demonstrated a higher accuracy. These models, if employed, are expected to provide a better control of cutting temperature in turning of hardened steel.

Cutting Temperature and Tool Wear Assessment of Turning Process with Minimal Quantity Lubrication

This paper presents an experimental investigation on cutting performance in turning of mild steel with application of minimal quantity lubrication (MQL) by using vegetable oils: canola oil, sunflower oil and palm oil. In order to study the effects of MQL on turning process, cutting temperature and flank wear were measured during the turning operations. Cutting temperature was measured using tool work thermocouple while flank wear was observed through SPG video microscope. The measured cutting temperatures and flank wear were also compared to that of dry cutting and water mist cutting. Results showed that among the vegetable oils, palm oil demonstrated highest cooling efficiency, at which reduction of 50 percent in cutting temperature compared to dry cutting. However, it was found out that MQL with canola oil yields the longest tool life. Reasons for such findings are also discussed in the paper.

The effect of application of cutting fluid with solid lubricant in suspension during cutting of Ti-6Al-4V alloy

The process of machining of hard materials such as titanium and its alloys, has an important role in the development of new machining techniques, such as cutting tools and coatings, with the aim to increase the machinability of these materials. Due to the poor thermal properties of the titanium, the cutting tool suffers accelerated wear which affects the tool life. This paper describes a study of the use of solid lubricant during the machining of Ti-6Al-4V in a turning operation. TiAlN (PVD) coated cemented carbide tool (class S15) was used. Dry tests, tests with lubricant and tests with lubricant with 20% by weight of solid lubricants: graphite mesh 325 (average particle size of 40μm), graphite mesh 625 (20μm) and molybdenum disulphide (MoS2, 6μm) were made. The output parameters are: tool life, surface roughness, cutting force and interfacial temperature (tool-work thermocouple). Tool flank wear, a major problem in machining of titanium alloys, was significantly reduced due to the action of the solid lubricants. Experimental results showed the superiority of molybdenum disulphide in relation to graphite in the turning process: reducing the tool wear, prolonging the tool life and improving the surface roughness. The solid lubricant may be a viable alternative to dry and wet turning. Thus, it may be inferred that proper application of solid lubricants in machining of Ti-6Al-4V alloy results in reduction in tool wear, which can lead to enhancement of productivity.

On Cutting Temperature Measurement During Titanium Machining With an Atomization-Based Cutting Fluid Spray System

The poor thermal conductivity and low elongation-to-break ratio of titanium lead to the development of extreme temperatures (in excess of 550 °C) localized in the tool–chip interface during machining of its alloys. At such temperature level, titanium becomes highly reactive with most tool materials resulting in accelerated tool wear. The atomization-based cutting fluid (ACF) spray system has recently been demonstrated to improve tool life in titanium machining due to good cutting fluid penetration causing the temperature to be reduced in the cutting zone. In this study, the cutting temperatures are measured both by inserting thermocouples at various locations of the tool–chip interface and the tool–work thermocouple technique. Cutting temperatures for dry machining and machining with flood cooling are also characterized for comparison with the ACF spray system temperature data. Findings reveal that the ACF spray system more effectively reduces cutting temperatures over flood cooling and dry conditions. The tool–chip friction coefficient indicates that the fluid film created by the ACF spray system also actively penetrates the tool–chip interface to enhance lubrication during titanium machining.

Effect of Pressure and Nozzle Angle of Minimal Quantity Lubrication on Cutting Temperature and Tool Wear in Turning

This paper presents an experimental investigation on effects of pressure and nozzle angle of minimal quantity lubrication (MQL) on cutting temperature and flank wear in turning. In manufacturing industries, there are always demands for the optimum cutting conditions for the most economical manufacturing cost. Hence, reduction in tool wear is essential for less expenditure with the knowledge of optimum cutting conditions of MQL. MQL, also known as near dry machining, has been acknowledged as an effective cooling technique in machining by applying vegetable oils in replacing the conventional flooding method due to environmental issues. By varying the operating pressures and nozzle angle with respect to the cutting zone, cutting temperature and flank wear are measured using a calibrated tool work thermocouple and SPG video microscope. Comparison was made between dry cutting, water mist cooling and MQL method with palm oil. Results showed that MQL with palm oil exhibits best cooling efficiency at 5 bar pressure and nozzle angle of 20o with reduction of 35% in tool wear and 23% in cutting temperature at higher cutting speeds.

Development of a tool–work thermocouple calibration system with physical compensation to study the influence of tool-holder material on cutting temperature in machining

The main objective of this work is the experimental investigation of the influence of tool-holder material on tool–chip interface temperature and on the surface temperatures of the cutting tool and tool-holder. The study was conducted in dry machining of grey iron with uncoated cemented carbide inserts, using identical cutting parameters. Five tool-holders were made with materials having different thermal conductivity: copper, brass, aluminium, stainless steel and titanium alloy. The tool-holders are identical and have the same constructive aspects obtained from the commercial tool-holder for machining grey iron. The temperature at the tool–chip interface was measured using the tool–work thermocouple method and the surface temperatures on the insert and tool-holders, by conventional T type thermocouples. The system was modified in order to develop an experimental procedure for the physical compensation of the secondary junctions and parasite thermoelectric e.m.f. signals. Also, modifications were carried out in a conventional tail-stock to obtain the e.m.f. signal between the rotating workpiece and the stationary insert, without significantly altering the stiffness of the system. The tail-stock with mercury bearing inside was insulated electrically. The internal connections became reference junctions at room temperature; otherwise, they would act as secondary junctions. The calibration of the tool–work thermocouple was developed in the experimental apparatus using the same modifications as implemented in the system. Besides the results obtained with the investigation of the effects of the tool-holder materials on the surface temperatures of the insert and the tool-holder and the tool–chip interface temperature, this research presents also contributions to the calibration and performance of the tool–work thermocouple method with physical compensation.

TEMPERATURE MEASUREMENT OF A CUTTING TOOL IN TURNING PROCESS BY USING TOOL WORK THERMOCOUPLE

Temperature at the cutting point of the tool is a crucial parameter in the control of the machining process. Due to advancement in the machining processes, a special attention has been given on the life of a tool. To achieve this, the best way is to apply the coating to the tool. In this study, coated and uncoated tungsten carbide tools were used and temperature occurred during machining were measured. Among the number of temperature measuring methods, the tool-work thermocouple technique is used as it is easy to install and inexpensive as compared to other methods. The procedure for the working of Tool-work thermocouple and method of calibration is described in this paper.

A40 切削温度計測による最適切削条件の決定について : 工具摩耗と切削温度との相関(OS13 環境適応型加工(2))

In cutting process, cutting condition has a strong effect on tool life and machining speed. It is required that high production system which balances tool life and production efficiency in factories. In this study, we focused on heat energy generated by cutting as the cause of tool wear. In order to equalize a cutting energy, cutting tests which at a certain material removal rate and wear mode of tool was estimated. In addition, two dimensional cutting was performed to calculate cutting energies. Furthermore, cutting temperature in each condition was measured by tool-work thermocouple measurement. At the these results, we clarified the correlation between the tool wear and cutting temperature and consider the effective search method for an optimum cutting condition.