Tool-workpiece Interface Temperature Research Articles

In-situ measurement and control of the tool-workpiece interface temperature during friction stir processing of 304/304L stainless steel

Friction stir processing of 304/304L stainless steel is an area of interest for repair of spent nuclear fuel canisters. To enable repair without canister deflection or fracture, it is necessary to define the limitations for the depth of the processing zone which will be critically dependent on the thermal history of the material. This work provides the first direct measurement of the interface temperature for friction stir processing of steel. The measured temperature is in the range of 850–1050 °C which is 20–30 % higher than previously reported values. Notably, the peak temperature occurs at the pin tip which is attributed to a higher sticking fraction and subsequently higher strain rate near the tool axis of rotation. Furthermore, a clear correlation between the temperature, grain size, and hardness is established within a single weld nugget and across different processing conditions. In the future, this data may lead to improved process modelling through direct validation and allow for property optimization through direct microstructure control.

Effect of tool–workpiece interface temperature control on the weld quality of a bobbin-tool friction-stir-welded aluminum alloy

Effect of tool–workpiece interface temperature control on the weld quality of a bobbin-tool friction-stir-welded aluminum alloy

Process parameter optimization for cutting tool-workpiece interface temperature during end milling of Aluminium alloy 6061 using Taguchi's experimental design

Process parameter optimization for cutting tool-workpiece interface temperature during end milling of Aluminium alloy 6061 using Taguchi's experimental design

Ultrasonic assisted turning of AISI 52100 steel using nanoparticle-MQL method

High cutting force and high cutting tool-chip interface temperature occur during machining of high strength materials like AISI 52100 by using conventional turning method and this makes to the difficult machining operation. Besides, in conventional turning (CT) of these materials, which has high abrasion resistance and hardness properties, an additional process such as grinding is required to achieve the desired surface quality. Ultrasonic assisted turning (UAT) method has been widely used in the machining industry in recent years, as it exhibits better surface quality, lower cutting forces, and cutting temperature than the CT method. This paper focused on experimentally and statistically determining the effects of different cutting parameters and cooling conditions (dry and minimum quantity lubrication-MQL) on surface roughness, workpiece surface texture, tangential direction cutting force, and cutting tool-workpiece interface temperature in the machining of AISI 52100 material by using UAT and CT methods. The experimental results revealed that significant improvements determined in the cutting forces and the surface roughness occurred in UAT compared to CT in all the cooling conditions. However, the increasing cutting speeds caused to observe higher interface temperature values in dry turning by the UAT method. Variance Analysis (ANOVA) was carried out to determine the significance grade of independent variables on dependent variables. According to ANOVA results, while the cutting speed is the most important factor on the surface roughness and the cutting zone temperature, and the cooling method is the most important factor on the cutting force. The effects of turning methods on corresponding surface topography, including surface defects, were evaluated. It is determined that in the surface topography analysis, feed marks are the main texture of the workpiece in the CT method while micro-level indentations and protrusions occurred on the workpiece surface in the UAT method.

System Identification Based Controller Design for Friction Stir Welding Process During Joining of Aluminium Metal Matrix Composites

Friction Stir Welding (FSW) process was initially implemented by modifying the milling machines. With the advancements in robotics and automation, movement along three primary axes are made controllable using computer integration. FSW being a temperature-dependent process, the temperature at the weld zone affects the weld quality since the microstructure is totally altered by the temperature variations. If welding is done at constant process parameters by ignoring the process disturbances, it would also result in undesirable material properties. From research studies, it is understood that tool pin position and spindle speed are significant process parameters contributing to heat generation during the joining process. In this study, an attempt is made to control the spindle speed of the rotating tool by measuring tool-workpiece interface temperature and vibrational disturbances during joining of Aluminium Metal Matrix Composite (Al-MMC) plates. The system model is estimated from the experimental data using the concept of system identification. Followed by, a Smith Predictor control scheme is developed and validated in a closed loop FSW system to examine the tensile strength.

A combined numerical and experimental approach for determining the contact temperature in an industrial ironing operation

Tribological conditions in forming operations depend on several parameters such as tool-workpiece interface pressure, surface expansion, sliding length, sliding speed, tool and workpiece materials and the roughness of the parts. Among indirect parameters, the most influential one is the tool-workpiece interface temperature, which directly influences the lubricant performance. Prior to testing new tribo-systems to determine their limits of lubrication, it is therefore important to find the interface temperature. However, measurement of the interface temperature in metal forming is difficult. The present work investigates the determination of the interface temperature in an industrial ironing operation, where severe process parameters lead to lubricant film breakdown and galling after several strokes. The methodology combines finite element simulations and experimental measurements. The overall procedure is based on a steady-state thermal analysis to determine the temperature distribution within the tool and a transient thermo-mechanical analysis of the ironing process when steady-state conditions are achieved. Results show that the proposed methodology applied to a single stroke can effectively and accurately predict the interface temperature in the test tool, thus avoiding the otherwise required thermo-mechanical FEM analyses of hundreds of strokes to reach steady-state. Furthermore, the influence of parameters, such as the predicted steady-state tool temperature, the friction coefficient and the heat transfer coefficient on the contact temperature, is analysed. It is concluded that the frictional heating is the primary cause for the peak temperature. By calibration of the friction coefficient and the heat transfer coefficient to ensure matching of the numerical results and the experimental measurements, a maximum tool-workpiece interface temperature of 158 °C was determined during the forward stroke and 150 °C during the backward stroke.

Parametric optimization in turning of AA2014/Al2O3 nano composite for machinability assessment using sensors

Aluminium metal matrix nano-composites (AMMNC) reinforced with various weight percentages of micro and nano Al2O3 particles have outstanding mechanical properties for variety of industrial, aerospace and automotive applications. However, the machinability of AMMNC is still a problem. The presence of abrasive particulates behaves like cutting edge for the tool during machining, resulting in unexpected tool wear, high tool workpiece interface temperature, enormous amount of cutting forces and vibration. In this study, experimental investigations were carried out to assess the machinability in turning of AMMNC under dry condition. A mathematical model was developed to predict the responses, namely surface finish, tool wear, work-tool interface temperature and cutting forces using linear regression analysis. Taguchi based optimization technique has been used to optimize the turning parameters for obtaining the best surface roughness of the components with reduced tool wear, temperature and cutting force. Multiple sensors were used to measure the responses to identify the optimum machining parameters. The frequency domain analysis is carried out to predict the dominant frequency band. Chip morphology analysis is also carried out to assess the machinability. Thus, this work helps to know about the effect of combined micro and nano-particles in the properties of AMMNC and its machinability.

Effect of Machining Parameters on Surface integrity during Dry Turning of AISI 410 martensitic stainless steel

The primary method of material removal from a cylindrical workpiece is conceivable by using turning process.This paper presents a comprehensive analysis of surface integrity in dry machining of AISI 410 martensitic stainless steel which is widely used material for automotive and aerospace applications. In the present work, the effects of turning process parameters such as cutting velocity, feed and depth of cut in dry turning of martensiticstainless steel has been investigated. Taguchi orthogonal array has been implemented to investigate the effect of process parameters on surface roughness and tool-workpiece interface temperature. A detailed study about the chip morphology and machined surface has been carried out using scanning electron microscope. It was noticed that golden color thick long ribbon type chip was produced at dry condition and side flow has been observed in chip.

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.

Calibration of dynamic tool–workpiece interface temperature measurement during friction stir welding

The objective of this work is to accurately measure the transient temperatures at the tool–workpiece interface during friction stir welding (FSW) using thermocouples that are embedded in the tool. Temperature sensors embedded in the friction stir (FS) tool provide a non-consumable localized temperature measurement capability that is crucial for process research, development, and control. A modification of the ASTM E-1461 standard for measuring thermal diffusivity with pulses of heat flux is proposed for calibrating the transient response of temperature sensors located near the surface of the FS tool. These tests enable the calculation of each sensor’s time constant, which are used in one-dimensional analytical models of the dynamic response to calculate the true interface temperature. Time constants between 21 and 43ms are measured for 0.25-mm-diameter, sheathed thermocouples located at the FS tool surface.

Temperature measurement and control of bobbin tool friction stir welding

Bobbin tool friction stir welding (BTFSW) is a relatively new, solid-state welding technology, but its control is not the same as the conventional friction stir welding (FSW) due to the unique welding tool structure. In this paper, closed-loop control system was developed and the Smith predictive proportional-integral-derivative (PID) control method was presented to assist the welding system in producing an appropriate interface temperature response. As it is difficult to accurately detect the temperature in full range of the welding zone, the tool-workpiece interface temperature is detected by thermocouple and wireless transmission technology. Initial experiments were conducted to derive a qualitative understanding of bobbin tool friction stir welding processes. Ziegler-Nichols setting method was adopted to determine parameters of the PID controller. While examining the capabilities of Smith predictive PID control in BTFSW, this paper focuses on the control effect of hysteretic characteristics of welding temperature during butt welding. A compensation strategy was setting gaps along the welding path, and the gap could affect the distribution of temperature. Through our experiments, we demonstrate that temperature control strategy is feasible, and the tensile properties of the weld are uniform along the welding direction.

Physics-based interpretation of tool-workpiece interface temperature signals for detection of defect formation during friction stir welding

The objective of the work is the reduction and eventual avoidance of post welding inspections that are currently needed to ensure defect-free welds. An analytical thermal model of the FSW process along with an analytical disturbance model is developed. This disturbance model relates defect formation to variations in the measured temperature and is based on experimental process identification. A dynamic disturbance observer computes an estimate of the disturbance signal, which is further processed in order to provide information about the presence of defects along the weld. Experiments for one kind of disturbance verify that the observer shows good tracking behavior.

Measurement of Tool-Workpiece Interface Temperature Distribution in Friction Stir Welding

The objective of this work is to develop an improved temperature measurement system for friction stir welding (FSW). FSW is a solid-state joining process enabling welds with excellent metallurgical and mechanical properties, as well as significant energy consumption and cost savings compared to traditional fusion welding processes. The measurement of temperatures during FSW is needed for process monitoring, heat transfer model verification and process control, but current methods have limitations due to their restricted spatial and temporal resolution. Previous work showed that temperatures at the tool shoulder-workpiece interface can be measured and utilized for closed-loop control of temperature. Adding an additional thermocouple at the tool pin-workpiece interface and performing a calibration of the measurement to gain better insight into the temperature distribution in the weld zone improved the method. Both thermocouples were placed in through holes right at the interface of tool so that the sheaths are in direct contact with the workpiece material. This measurement strategy reveals dynamic temperature variations at the shoulder and the pin within a single rotation of the tool in real-time. It was found that the highest temperatures are at the shoulder interface between the advancing side and the trailing edge of the tool, closer to the advancing side. The temperature distribution was mostly affected by travel speed and the temperature difference within one tool rotation was found to be between 10 °C and 50 °C, depending on the process parameters. The dynamic temperature measurements obtained with the current system are of unmatched resolution, fast, and reliable and are likely to be of interest for both fundamental studies and process control of FSW.

Effects of tool–workpiece interface temperature on weld quality and quality improvements through temperature control in friction stir welding

A real-time wireless temperature measurement system has been developed and successfully implemented for closed-loop control of tool shoulder–workpiece interface temperature. The system employs two thermocouples in through holes and measures the shoulder and pin interface temperatures with an angular resolution as small as 10°. Both temperatures correlate with weld quality (mechanical testing and weld cross sections), e.g., all welds in 4.76-mm-thick 6061-T6 with an average shoulder interface temperature below 520 °C and an average pin interface temperature below 460 °C fail in the weld zone instead of the heat-affected zone, have unacceptable tensile strengths and in some cases voids. Similarly, welds with shoulder temperatures above the solidus temperature result in a degradation of the weld quality. It was found that a shoulder interface temperature of 533 °C results in the highest weld quality; hence, this temperature should be used as the setpoint temperature in the control system with a constant travel speed of 400 mm/min. The temperature measurement strategy was shown to be able to indicate welds with insufficient shoulder–workpiece contact, thus potentially identifying and preventing welds with detrimental weld quality due to lack of penetration. It was shown that backing plates of different thermal diffusivity change the heat flow out of the weld zone, hence weld temperature, and caused a measurable impact on the weld strength. By changing other process parameters, e.g., through a temperature control system, weld quality can be maintained in the presence of such changing thermal boundary conditions.

Temperature Investigation of High Speed Milling High Manganese Steel

This paper analyzes the influence of cutting parameter to temperature in high speed milling high manganese steel process. By measuring tool-workpiece interface temperature and analyzing temperature distribution in the workpiece, the experimental results show that maximum temperature on tool surface increases with the increase of spindle speed, while the temperature of the total workpiece increases little in the cutting process. Temperature variation law of tool-workpiece interface and total workpiece are matched with the traditional processing mechanism well.

Experimental research on the dynamic characteristics of the cutting temperature in the process of high-speed milling

The cutting temperature is a key factor which directly affects cutting tool wear, workpiece surface integrity and machining precision in the high speed machining (HSM) process. The purpose of this paper is to present an inverse heat-transfer model considering three-dimensional transient heat conduction to calculate the heat flux and the temperature distribution on the tool–workpiece interface in the high speed milling process. The model was set up by a finite element method based on Beck’s inverse heat-conduction theory and was verified by numerical simulations and a series of experiments which aimed to obtain the surface temperature data of a thin-walled workpiece with the aid of an infrared thermometer and the tool–workpiece interface temperature by an embedded artificial thermocouple. The dynamic characteristics of the cutting temperature in high-speed milling aluminum alloy were studied systematically. The numerical simulation results revealed that there was a close agreement between the calculated temperature value and the measured temperature value of the cutting interface in high-speed milling of aluminum alloy. The inverse heat-conduction method can be used to estimate the heat flux flowing into the workpiece and the temperature distribution on the tool–workpiece interface. Using the infrared thermometer as a remote sensor can solve the problem of measuring the temperature in high-speed milling and also it can be used as an approach to reveal the cutting mechanism of high-speed milling. There exists a critical cutting speed in the high-speed milling aluminum alloy. The value of this critical speed will be different for the different cutting conditions. Constant feed per tooth must be kept in high-speed milling to efficiently suppress excessive heat generation while obtaining a high material removal rate, especially for machining difficult to-cut materials with a thin-wall construction. The average tool–workpiece interface temperature is influenced by the thickness of the workpiece. The related temperature distributions will be very beneficial to the optimal construction design for the thin-wall parts used in the aeronautics and astronautics as well as die and mold industries.

工具‐加工物接触面温度の測定

Temperature of interface between a cutting tool and a workpiece is measured using two-color pyrometer with a fused fiber coupler. A conical tool is used as the cutting tool which is made of translucent alumina sintered under HIP, and 0.55% carbon steel is used as a workpiece. The infrared rays radiated from the interface and transmitted through the conical tool are accepted by a fused fiber coupler and led to two infrared detectors of different spectral sensitivity. Temperature is obtained by calculating the ratio of the output voltage from these two detectors. The results obtained are as follows. The temperature increases very rapidly and reaches 1000°C at about 40 μs after the beginning of cutting. The rate of increase of temperature is very great : about 108 °C/s at the cutting speed of 1 500 m/min. The temperature increases with the increase of cutting speed, but at a speed faster than 1000 m/min its influence is small. The temperature shows a tendency to saturate about 1300-1400°C as the cutting speed increases.

A study of grinding damage in magnesium oxide single crystals

The sub-surface and surface damage produced by alumina and diamond grinding wheels has been studied as a function of material removal rate. Sub-surface damage is characterised in all cases by a discrete, dense layer of dislocations adjacent to the machined surface. The depth of the layer increases with material removal rate. The nature of the surface damage depends on the mechanism of material removal. As long as the cutting points are unloaded and the residue can escape the material is removed in a brittle manner. This is always the case for the diamond wheel and occurs for low rates of material removal with the alumina wheel. When the cutting surface is loaded with residue, the tool-workpiece interface temperature becomes so high that the material is removed by plastic flow. The finished surface is burnished. Unfortunately as the burnished surface cools down thermal quenching produces a network of surface cracks.