Cutting Temperature Measurement Research Articles

Oxidation behaviour of NiSi–NiCr thin film thermocouples and antioxidation effect of SiNxOy film

NiSi–NiCr thin film thermocouples (TFTCs) have significant application value as contact temperature sensors in cutting temperature measurements owing to their fast response and negligible volume. However, due to the relatively high chemical activity of Ni-based alloys, high-temperature oxidation strongly affects the operational reliability of NiSi–NiCr TFTCs. In this respect, depositing an anti-oxidation coating onto the surface of NiSi–NiCr TFTCs is considered an effective way to protect them in high-temperature environments. In this study, NiSi and NiCr films were deposited on cemented carbides and annealed at 200 °C–600 °C in air. Scanning electron microscope, X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, and four-probe resistivity tests were used to characterize the microstructure and resistivity of NiSi and NiCr film. Then SiNxOy films were deposited onto the NiSi and NiCr films and compared with uncoated samples after annealing at 600 °C. The effect of SiNxOy films on the thermal stability and thermoelectric output of NiSi–NiCr TFTCs was investigated. The results show that the NiSi film was partially oxidized at 200 °C and entirely oxidized when the temperature exceeded 400 °C. The completely oxidized NiSi films had evident defects and cracks, and the resistivity increased by a factor of over 1000. The NiCr film could not be completely oxidized at 600 °C, which is attributed to the formation of Cr2O3 as an external oxide barrier layer. Below 600 °C, SiNxOy films could effectively protect NiSi and NiCr films from oxidation. Thus, the addition of SiNxOy film increases the maximum temperature at which NiSi–NiCr TFTCs can be used.

Multi-material laser powder bed fusion of embedded thermocouples in WC-Co cutting tools

During machining processes, due to deformation of the material and friction of the chip along the tool surface, a significant amount of heat is generated, particularly in the cutting zone, thus leading to a wear increase and consequent tool life reduction. Therefore, the ability to assess the cutting temperature in real time is extremely important to better understand heat generation, thus contributing to the development of more effective strategies for reducing machining costs and increasing tool life and productivity.This work proposes the fabrication of embedded additively manufactured K-type and N-type thermocouples in sintered WC-Co substrates by multi-material laser powder bed fusion for cutting temperature measurement in real time. Results showed that this approach is able to produce dense and continuous K-type and N-type embedded thermocouples with no evidence of severe defects, being found in the calibration tests a linear relationship with temperature, with a Seebeck coefficient at 20 °C of 40.8 μV/°C for K-type thermocouples and 16.5 μV/°C for N-type thermocouples. Turning tests revealed that the developed multi-material laser powder bed fusion approach is effective for manufacturing WC-Co cutting tools with 3D printed embedded thermocouples with the ability to measure precisely and accurately cutting temperature in real time during machining processes.

Integrated design and fabricate of high sensitivity built-in thin-film thermocouple temperature measurement tool

Abstract Cutting temperature is playing a key role in evaluating the cutting process, which significantly affects the tool wear and the quality of the workpiece. Aiming at the problems of low precision, low aging, and poor stability of cutting temperature measurement on the front tool face, an integrated design and production scheme of a high sensitivity built-in wireless temperature measurement tool was proposed. The temperature distribution position on the front tool face was analyzed with 3D finite element simulation software, and the thermal contact position of the main and secondary film thermocouples was determined. SiO2 insulated films and NiCr/NiSi film thermocouples were prepared on the front tool surface by femtosecond laser micromachining, electrolyte-plasma polishing, plasma enhanced chemical vapor deposition and magnetron sputtering, and a static calibration experiment system for sensitivity and accuracy of the temperature measuring tool for the film thermocouple was established, and Seebeck coefficient of the film thermocouple was obtained. According to the actual cutting conditions, the wireless temperature measuring system of the thin film thermocouple tool was built and the field cutting test was carried out to obtain the influence law of different cutting parameters on the cutting temperature, and further verify the feasibility of the thin film temperature measuring sensor. The research results show that: Seebeck coefficients of the two kinds of thermocouples prepared by the NiCr/NiSi thin film thermocouple temperature measuring tool are 34.97 μV/°C and 34.96 μV/°C, and the slope of the temperature data fitting curve is 1.00398 and 0.997475, respectively. The linear correlation coefficient R2 is close to 1, which is close to the standard K-type thermocouple, which shows good sensitivity and accuracy. At the same time, the temperature measurement results are close to the commercial standard K thermocouple, and the error is less than 5%, indicating that the developed film thermocouple has a high measurement accuracy and can meet the needs of temperature measurement. Actual cutting test is carried out with developed wireless temperature measuring device of thin film thermocouple, which shows this device can meet the requirements of tool temperature measurement, and the feasibility of thin film temperature measuring sensor is further verified. The research provide technical reference for industrial intelligent manufacturing in order to realize the wireless measurement of cutting area temperature of tool front.

Review of Cutting Temperature Measurement Methods.

During the cutting process, large quantities of emitted heat are concentrated on a small surface area of the interface between the workpiece and the cutting edge. The resultant very high temperature significantly affects the tool life. Knowledge of maximum temperatures to be expected on the cutting edges is important, as it allows the cutting conditions to be adjusted in such a manner that the critical value of thermal resistance is not exceeded for the cutting material. In effect, the maximum effectiveness of the working process is maintained. This article offers a systematic presentation of methods used in cutting temperature measurements. It discusses their advantages and disadvantages, as well as the usefulness of the individual methods in different types of machining processes. It also points to the possibility of methodological errors which significantly reduce measurement accuracy. The above issues are believed to justify a discussion of different cutting temperature measurement methods. The conclusions here presented may be of particular importance to researchers interested in the field, especially in high-efficiency machining, new cutting materials and cutting-edge protective coatings, as well as various methods for cutting fluid applications. They may allow a more informed selection of measurement methods most suitable for particular situations.

Novel approach of cutting temperature measurement in sustainable milling of Ti-6Al-4V alloy

Ti-6Al-4V alloy has widespread uses in a variety of engineering applications such as in the manufacturing of aerospace, automotive, and prosthetics body-parts owing to its unique characteristics. However, the machining of Ti-6Al-4V generates high cutting temperature due to poor thermal conductivity. This high cutting temperature triggers chemical reactivity of the alloy with the tool material and accelerates the edge wear. Therefore, the cryogenic coolants are used to improve the cutting performance, but their poor lubrication allows for high cutting forces. Hybrid lubri-coolants could be an alternative to reduce the temperature efficiently. The simulation of hybrid lubri-coolants by Finite Element Modeling (FEM) is an interesting to explore the high-performance cutting of hard titanium alloy. The current study compares the cutting temperatures using DEFORM® FEM simulations software and to foresee the cutting temperatures in milling Ti-6Al-4V at various levels of cutting speeds Vc (100–300 m/min), and feed per tooth fz 0.08–0.12 mm/z and under effect of hybrid lubri-coolants (ethanol, ester oil, and hybrid ethanol-ester oil). Initially, the 2D milling models were developed and predicted results were compared to milling experiments. The comparison of experimental and simulation cutting temperatures revealed a maximum of 6.5 % error. Thus, it can be concluded that 2D modeling is an effective tool to predict the milling temperatures within a reasonable error.

Real-Time Cutting Temperature Measurement in Turning of AISI 1045 Steel through an Embedded Thermocouple—A Comparative Study with Infrared Thermography

During machining processes, a high temperature is generated in the cutting zone due to deformation of the material and friction of the chip along the surface of the tool. This high temperature has a detrimental effect on the cutting tool, and for this reason, it is of the utmost importance to assess the cutting temperature in real time during these processes. Despite all the advances and investigation in this field, accurately measuring the cutting temperature remains a great challenge. In this sense, this work intends to contribute to solving this problem by experimentally evaluating the potential of the developed approach for embedding thermocouples into the rake face of cutting tools for measuring cutting temperature in real time during dry turning of AISI 1045 steel for different cutting parameters and comparing the obtained results with infrared thermography measurements at the exact same point. A well-defined, smooth micro-groove with good surface quality was produced by laser surface modification. Then a laser-welded K-type thermocouple was fixated in the micro-groove with a MgO ceramic adhesive, ensuring protection from wear and chips, which allowed the creation of WC-Co cutting inserts with the ability to measure cutting tool temperature with a maximum error of 0.96%. Results showed that, despite yielding the same trend, the tool temperature measured by the IR thermographic camera was always lower than the temperature measured by the K-type embedded thermocouple. The proposed embedded thermocouple method proved to be a reliable, precise, accurate, and cost-effective approach for real-time temperature measurement capable of providing useful information for cutting parameter optimization, thus allowing increased productivity and tool life.

Cutting temperature measurement using a novel near-infrared two-color pyrometer under dry and wet cutting of Ti‐6Al‐4V alloy

Due to the poor thermal properties of titanium alloys, heat generated and accumulated in the cutting area significantly affects tool life and workpiece quality. Although some methods have been proposed to measure the cutting temperature during machining titanium alloys, there still exist disadvantages including low spatial-temporal resolution, low measuring accuracy, restricted usage environment, etc. In this paper, a novel near-infrared two-color pyrometer system is developed and applied to measure the cutting zone temperature under dry and wet cutting of Ti‐6Al‐4V alloy. The developed pyrometer can eliminate the emissivity effect and shows a good linear relationship between the output signal ratio and the calibrated temperature. Meanwhile, the developed pyrometer exhibits good dynamic response and high measuring accuracy when measuring tool edge temperature and chip temperature in dry cutting conditions. In addition, a reliable sealing for cutter assembly is developed to overcome the influence of cutting fluid on the optic-fiber probe and the developed pyrometer can measure the tool edge temperature quickly and accurately in wet cutting conditions. In summary, the novel near-infrared two-color pyrometer system is validated to be quick responsiveness, high measuring accuracy, and good working stability when monitoring the cutting zone temperature under dry and wet cutting of Ti‐6Al‐4V alloy.

Temperature measurement performance of thin-film thermocouple cutting tool in turning titanium alloy

The measurement of cutting temperature is one of the most important research topics in the field of cutting. Traditional technology for cutting temperature measurement has limitations because it cannot accurately measure the real transient temperature change in the cutting area. In this study, a thin-film thermocouple sensor with high temperature measurement accuracy and rapid response was positioned near the cutting tool tip to prepare a thin-film thermocouple temperature-measurement tool. Its Seebeck coefficient was 48.13 μV/°C, and the highest temperature difference measured between cold and heat regions was 600 °C. The cutting temperature of a TC4 titanium alloy was measured using an infrared thermal imager and the proposed thin-film thermocouple temperature measurement tool in an orthogonal turning test. The test results were analysed to verify the reliability, accuracy, and repeatability of cutting temperature measurements. The cutting length could extend beyond 1500 m.

In-Process Cutting Temperature Monitoring Method Based on Impedance Model of Dielectric Coating Layer at Tool-Chip Interface

This paper introduces a novel approach to in-process monitoring of the cutting temperature at the tool-chip interface (TCI). Currently, there are no tools available in the commercial market for measuring and monitoring cutting processes at the TCI region. Therefore, most of the studies about evaluating cutting temperature rely on simulation results without knowing the true temperature at the actual TCI region. In addition, recent cutting temperature measurement techniques have measurement errors occurring resulting from difficulty in estimations at the TCI region. However, the proposed method enables the measuring of cutting temperature by directly probing the localized TCI using a cutting tool coated with dielectric material. The study was conducted by utilizing the impedance characteristics of the dielectric outer layer of the cutting tool. A chemical vapor deposition (CVD) diamond coated insert that is commercially available was considered for the study to avoid wear effect. Impedance response of the dielectric layer under varying temperature conditions is assessed by Nyquist diagram using an impedance analyzer. The result of the Nyquist diagram showed temperature-dependent impedance characteristics that showed good agreement with the results from the thermal experiment which was a comparison between impedance response and elevated temperature. The impedance at the TCI for monitoring cutting temperature is measured under a turning process on a lathe using a constant current source. The impedance responses showed a significant decrease in impedance under various machining conditions which indicates a rise in cutting temperature. Moreover, different machining conditions showed different temperature profiles. The impedance responses were further characterized for depth of contact, which found that a drop in impedance corresponded to an increase in depth of contact. Therefore, the study showed that in-process monitoring of the cutting temperature is possible using an impedance model of the dielectric coating layer at the local TCI. Furthermore, with its versatility, this method is expected to measure the vibration, chatters, cutting force, and so on, as the results showed that impedance is not only sensitive to temperature but also to contact area. The application and expectation of this study is to provide real-time machining data to help end users in manufacturing industry to improve product quality, productivity, and prolonged lifespan of cutting tools.

Cutting temperature measurement in turning using fiber-optic multi-spectral radiation thermometry and its application in tool wear status recognition

The cutting temperature is essential for phenomena understanding and quality improvement in metal cutting while its in-situ online measurement is still a challenge. This paper presents a near-infrared fiber-optic multi-spectral method for in-situ online cutting temperature measurement. Using thermal radiation spectrum for temperature measurement, the method optimizes the lower limit of temperature measurement to 150 °C while improving accuracy. The calibration shows that in the range of above 250 °C, the average relative error of temperature measurement is stable below 0.5%. The titanium alloy cutting experiments are carried out. In-situ online measurement of tool temperatures in dry/wet cuttings are realized using the self-developed system. The influence of cutting parameters on cutting temperature is studied, and the real-time response of the temperature measurement system to the cutting state is verified. As for industrial application, the capability of the system in heavy-duty turning is proved by railway wheelsets turning experiments. Tool wear experiments are conducted, and a positive correlation between the cutting temperature and tool wear is revealed. Tool wear status recognition is realized based on cutting temperature by sparse autoencoder and k-means clustering, and a recognition accuracy of 97.3% is achieved. These results indicate promising prospects in cutting mechanism research, machining status monitoring and industrial applications, empowering the advancement of intelligent manufacturing and industry 4.0.

Cutting temperature measurement and prediction in machining processes: comprehensive review and future perspectives

Cutting temperature measurement and prediction in machining processes: comprehensive review and future perspectives

Finite element investigation of cutting performance of Cr/W-DLC/DLC composite coated cutting tool

DLC has been applied as coating material in the machining of difficult-to-cut materials, and shows a good cutting performance. In this study, Cr/W-DLC/DLC-coated tools were compared with other three kinds of coated tools (TiC-, TiAlN-, Al2O3-) to investigate the cutting performance in the machining of Al–Si alloy. The influence of Cr/W-DLC/DLC-coated tools on the cutting performance under different cutting speeds was studied. Cutting force, cutting temperature, heat partition coefficient, cutting deformation rate, plastic deformation of machined surface, the interface temperature, and stress were investigated numerically with the aid of finite element method (FEM). Actual cutting experiments were carried out to verify the FEM models by means of the cutting force and cutting temperature measurement. The investigation results show that Cr/W-DLC/DLC-coated tool had the best cutting performance among these four kinds of coated tools. With the increasing of cutting speeds, cutting force and cutting temperature showed an increase trend, while the plastic deformation depth of machined surface and heat partition into cutting tool all showed a decrease trend during the machining with Cr/W-DLC/DLC-coated tool. This investigation can provide the theory basis or technical guidance for the cutting practice with Cr/W-DLC/DLC-coated tools.

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.

Online estimation of the heat flux during turning using long short-term memory based encoder-decoder

Heat flux during machining has received extensive attention due to its importance for understanding the cutting mechanism and promising prospects on intelligent manufacturing. Research on heat flux estimation by inverse heat conduction methods faces many challenges, including measurement error amplification, stability of the methods, and limitations for applications. In this paper, we introduce a long short-term memory (LSTM) based encoder-decoder (ED) scheme in online estimation of the heat flux imposed at the tool-chip region during turning. The math-physical model and finite element model are established to generate training datasets. Numerical tests using simulated heat flux and temperature data representing different machining conditions are carried out to evaluate the method performance. Compared with other artificial intelligence methods such as multilayer perceptron, convolutional neural networks and LSTM, the LSTM-ED model performs better at all tested noise levels (1≤σ≤20K) with acceptable time cost for online process. Effects of the location and number of sensors on the accuracy of heat flux estimations are also investigated. Experimental validations based on cutting temperature measurements by five thermocouples located in the insert are conducted. Both numerical and experimental tests indicate the potential of the LSTM-ED method for online heat flux monitoring in scientific research and industrial production.

Cutting tools embedded with thin film thermocouples vertically to the rake face for temperature measurement

Smart tools instrumented with thin film thermocouples for online cutting temperature measurement are promising in intelligent manufacturing. However, the surface-mounted planar devices are easily damaged through delamination and abrasion due to the high temperature, great stresses and harsh friction. This paper reports a novel approach to embed the thin film thermocouples in vertical direction to the tool rake face for protection. Attention is also paid to improve the quality of the vertically deposited thin films on the lateral walls of the micro-grooves. Experimental tests have been done to obtain the sensitivity and response of the sensors in the tool. The embedded sensors function well in monitoring the cutting temperature in cutting tests of a titanium alloy.

Development of a cutting edge temperature measurement of end mill tool by using infrared radiation technique

This paper describes the development of cutting temperature measurement of end mill tool by using infrared radiation technique approach. Compared to conventional thermocouple technique, infrared radiation technique is an advance method of measuring temperature which featured high accuracy, high response rate, wide range of temperature scale detection and almost compatible with all materials used in the manufacturing industry. We measures the emission of infrared radiation from the source, which is cutting edge of tool by using photocells that contains InAs and InSb photovoltaic detectors. Photocells converts the infrared radiation to a voltage signal and then recorded by oscilloscope followed with a calibration with its corresponding temperature. This paper discussed about the calibration method, cutting experiment setup, the limit of infrared radiation level detected by photocells, signal correction of output signal, and relations of peak signal formation with rotation of end mill tool. The developed pyrometer is also capable to profile the cutting tool’s rotation based on the movements of infrared radiation’s emission at cutting tool’s edge. The conclusion was that the measurement of cutting temperature of high speed machining by using infrared radiation technique is possible. The developed pyrometer are capable to detect temperature changes at a span of 0.01 ms.

Cutting temperature measurement using an improved two-color infrared thermometer in turning Inconel 718 with whisker-reinforced ceramic tools

Great heat will generate in turning Inconel 718 with whisker-reinforced ceramic tools. The generated great heat damages the machined surface quality. More attentions have been paid to the methodologies for accurately measuring cutting temperature in the cutting zone. However, the current methodologies of measuring cutting temperature have the disadvantages of destroying temperature field, uncertain emissivity and low measuring accuracy. In this paper, an improved two-color infrared thermometer is developed and used to measure the maximum cutting temperature in the cutting zone. The contactless measurement and the eliminated emissivity effect can improve the authenticity of the measured maximum cutting temperature. The fast response time 10 ms and the high measuring accuracy of the improved two-color infrared thermometer can meet the requirements of measuring maximum cutting temperature. The measured maximum cutting temperature increases exponentially with the cutting speed. The improved two-color infrared thermometer can be adopted to more complicated situations by moving the reliable fixed tripod and convenient focusing. The improved two-color infrared thermometer is proved to be a convenient, effective and economic methodology for accurately measuring the maximum cutting temperature in the cutting zone.

Built-in thin film thermocouples in surface textures of cemented carbide tools for cutting temperature measurement

Cemented carbide tools embedded with thin film thermocouples are presented in this paper, to monitor the tool temperature distribution in machining of titanium alloys. In order to protect the thin film sensors from the flowing chips, the fabrication processes which include preparation of micro-grooves on the rake face of commercial tungsten carbide cutting inserts and installation of the thin film sensors in the grooves are proposed. Six K-type thin film thermocouples are implanted in the grooves at a depth of about 100 μm with a 100 μm × 50 μm hot junction area. The tests show that the sensors are reliably insulated with the alloy substrate and have good linearity and uniformity in the measurement. The performance of the fabricated inserts are evaluated in a titanium alloy (Ti6Al4V) turning process with the cutting temperature close to the tool-chip interface obtained online for both continuous and interrupted cutting experiments. The fabricated sensors show good sensitivity and improved durability during the cutting processes.

Prediction model of high-speed oblique cutting temperature based on LS-SVM

High-speed oblique cutting temperature is an important factor in ensuring workpiece quality. In order to gain the temperature real time in the cutting process, a prediction method based on least squares support vector machine (LS-SVM) was proposed. To verify the feasibility of the method, firstly, the high-speed cutting temperature model was established based on LS-SVM, and the major operation parameters (cutting speed, feed rate, axial depth of cut, and radial width of cut) were chosen as the model input based on oblique cutting process analysis; secondly, the cutting experimental scheme was designed applying the Box–Behnken experimental design method for gaining more cutting temperature data and less experimental times. Then, a high-speed cutting temperature measurement system was established based on a MCV850 vertical machining center for testing the reliability of model prediction. Finally, the model prediction results based on LS-SVM and neural networks were compared. And the results show the prediction error of the model gained is less than 1 %, and taking two-group random parameters as test data with different with Box–Behnken experimental parameters designed before, the percentages of prediction data deviation measurement were 0.83 and 0.51 %, respectively. The results demonstrate the feasibility of applying the cutting temperature prediction model in predicting the main required processing parameters.

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.