Workpiece Temperature Research Articles

Multi response optimization of nozzle process parameters in MQL assisted face milling of AISI 52,100 alloy steel using TGRA

Abstract The demand for near dry machining increases due to the adverse effect of cutting fluid on health and the environment. MQL technique offers itself as a suitable alternative for cooling and lubrication at the cutting zone during machining. In MQL mixture of a very low quantity of lubricant and compressed air is sprayed at the cutting area. Economic factor also makes it desirable as it reduces the cutting fluid cost. In this paper, the effect of MQL parameters on surface roughness and temperature during face milling of AISI 52,100 alloy steel is studied. The MQL nozzle parameters, the nozzle elevation angle, and the spray distance were selected as a process variable. A full factorial design was used to conduct the experimentations on a vertical machining center; the analysis was done by using the Analysis of variance (ANOVA) approach. A higher value of grey relational grade gives the best combination of MQL parameters for both output responses (surface roughness and temperature). The result shows that the nozzle elevation angle at 450 and a spray distance of 40 mm was the optimum process variable for both the excellent surface finish of the work piece and low temperature at the cutting zone.

Experimental investigation and dimensional analysis of friction drilled hole on 6082 aluminium pipe using hardened M2 centre drill

The main aim of this research is to investigate the form drilling parameters using Buckingham Pi-Theorem and identifying the most effective parameters for effective heat generation. It is important to identify the most effective parameters which give a cylindrical shaped bushing without significant radial fracture or petal formation. To produce better results, the parameters of friction drilling are optimized by dimensional analysis. Effect of work piece temperature, spindle speed, and feed rate in experimentally measured along with torque. The designed and developed high speed steel M2 tool is used for friction drilling of Al 6082 work piece. The present research develops theoretical analysis of the various friction drilling parameters by conducting the experiments on friction drilling process over aluminium tubing material of AL 6082. The presented work also attempts the application of Buckingham pi-theorem to find what parameters are influencing the friction drilling process and using dimensionless parameters.

Application of preliminary low-temperature heating for cold forming of complex parts on cold former

The results of experimental studies of flow curves of 32CrB4, 20G2R and 1.4034 (analogue of 40Kh13 steel) steels at different heating temperature of workpieces are presented. Rational intervals of preliminary lowtemperature heating of workpieces made of studied steels are obtained. It allows to decrease forces during cold forging, loads on the working tool and to increase of tool life time up to 2 times.

A review on conventional and thermal assisted machining of titanium based alloy

Advanced engineered and difficult-to-cut materials are in stringent demand for industries, due to their inherent properties and applications in aircraft structural and engine parts. The machinability attributes, for example, higher cutting power, more cutting temperature, reduced surface integrity and lesser tool life related to having numerous difficulties to the researchers, and these challenges arise when machining process is being done on the new and tough materials. Hence conventional machining approaches of super alloys limit those applications due to processing difficulties in attaining high reliability and surface integrity, associated with high machining cost. In recent-past, many research efforts focused on improving the machinability viz-Thermal assisted Machining (TAM). This process uses external heat sources that raise the workpiece temperature and make softer the work material nearby leading of the cutting tool. Increased temperature by the side of shear zone decreases the workpiece yield strength and work hardening, causing in plastic deformation of materials that could help for ease of machining, also affects the material removal rate (MRR). TAM is associated with higher material removal rate, higher surface finish, and also better control of time on machining. It helps in reducing cutting forces thereby increasing the surface finish. Titanium alloys generally used in bio-implants requires high precision in dimensions, TAM is the best machining practice for Titanium and its alloys. The present work survey, and shorten the potential utilization of Titanium based alloys and control parameters, current advancement, advantages and difficulties. Many parameters affect the machining characteristics (surface integrity, material removal rate, tool life, residual stresses etc), and tool geometry and corresponding research method, tool wear, cutting speed, etc., Tool materials, different heat methods are the primary ones worth to investigate.

Математическое моделирование распределения энергии при вводе в материал изделия луча в процессе электронно-лучевой сварки

Modeling of electron beam welding processes is one of the most important parts of applied research, because full-scale experimental investigations are either expensive or highly labor intensive. The problem of modeling the temperature fields at the electron beam entering stage during welding is considered. The aim of the study is to simplify the adjustment of the electron beam welding process technological parameters and to elaborate and develop more efficient control algorithms through replacing full-scale experiments by model ones. The mathematical body of the proposed solutions is constructed using the theories of thermal and welding processes, based on which the energy distribution mathematical models are developed. For practically implementing the computations, an algorithmic support is presented that allows the mathematical models to be applied in modern modeling systems, such as Matlab, Comsol Multiphysics, and Ansys. Apart from supplementing the set of existing mathematical models of the electron beam welding process, the obtained models for calculating the temperature in the beam entering area widen their application for calculating and optimizing the welding process, taking into account the workpiece temperature in the electron beam entering area. By using the proposed solutions, several numerical experiments were carried out for a workpiece made of VT-14 titanium alloy and two pieces of different thickness made of AMg-6 aluminum alloy. The obtained temperature fields and the rms values of process parameters are almost identical with the results of previously conducted full-scale studies.

Повышение режущей способности шлифовального круга при обработке заготовок из пластичных сталей наложением ультразвуковых колебаний на заготовку

The study aimed to identify the relations between the sticking intensity and ultrasonic vibrations (UV) used for processing and evaluate the wheels’ performance when grinding ductile materials blank parts. The authors carried out the numerical simulation of local temperatures and the 3H3M3F steel workpiece temperature when grinding by ultrasonic activation. The study determined that the application of ultrasonic vibrations with the amplitude of 3 µm causes the decrease in local temperatures by 13…40 %, and in blank part temperature – up to 20 %. The calculation identified that the activation of ultrasonic vibrations with the amplitude of 3 µm causes the decrease in the glazing coefficient by 33 % for cutting grain and by 7 % for deforming grain. When increasing the longitudinal feed rate or the grinding depth, the glazing coefficient increases to a lesser degree when using the ultrasonic vibration than in the case without ultrasonic activation. The authors carried out the numerical simulation of local temperatures when scratching the 3H3M3F steel specimens by single abrasive grains with ultrasonic activation. The sticking deformation and the stresses resulted from this deformation and affecting the junction points of sticking with grains with and without ultrasonic vibrations application are calculated. The experimental research included the micro-cutting of specimens with single abrasive grains. The experiments identified that the abrasive grains wear out and glaze to a lesser degree when micro-cutting a workpiece with ultrasonic vibrations activation. The lowering of the intensity of sticking of the workpiece material particles to the abrasive grains due to the adhesion causes the decrease in the glazing coefficient when using ultrasonic activation. The study considered the possibility to enhance the efficiency of flat grinding through the use of the energy of ultrasonic vibrations applied to a blank part in the direction with the grinding wheel axis. A workpiece fixed in the device between the vibration transducer and the support is one of the components of a vibration system. The authors performed the experiment when grinding 3H3M3F and 12H18N10T steel workpieces with the wheel face. When grinding with ultrasonic vibrations, the grinding coefficient increases up to 70 %, and the redress life increases twice or thrice.

Surface integrity in laser-assisted machining of Ti6Al4V

In laser-assisted machining (LAM), the laser source is focused on the workpiece as a thermal source and locally increases the workpiece temperature and makes the material soft ahead of the cutting tool so using this method, the machining forces are reduced, which causes improving the surface quality and cutting tool life. Machinability of advanced hard materials is significantly low and conventional methods do not work effectively. Therefore, utilizing an advanced method is inevitable. The product life and performance of complex parts of the leading industry depends on surface integrity. In this work, the surface integrity features including microhardness, grain size and surface roughness (Ra) and also the maximum cutting temperature were investigated experimentally in LAM of Ti-6Al-4V. According to the results, cutting speed has inverse effect on the effectiveness of LAM process because with increasing speed (15 to 63 m/min), temperature decreases (524 °C to 359 °C) and surface roughness increases (0.57 to 0.71 μm). Enhancing depth of cut and feed has direct effect on the process temperature, grain size, microhardness and surface roughness.

Effect of rake angle and tool geometry during machining process of AISI 4340 steel in finite element approach

Due to high impact resistance and abrasive resistance, AISI 4340 has been widely used in aircraft landing gear and high power transmission gears. During high speed machining process friction plays more important role in increasing temperature between tool and work piece. Owing to higher temperature in work piece and cutting tool increases wear rate and reduces the tool life. This paper investigates the effect of rake angle in normal cutting tool with various tool geometry and micro groove cutting tool during machining AISI 4340 steel with tungsten carbide cutting tool in simulation environment. Tool wear rate of micro groove cutting tool is minimum compared with other cutting tool with dissimilar tool geometry. Also micro groove tool minimize the cutting tool interface temperature.

Characterization of material strain and thermal softening effects in the cutting process

Accurate descriptions of workpiece behaviors are indispensable for achieving reliable simulations of the cutting process. However, the material plastic constitutive models obtained through conventional material tests do not apply in the ranges of strain and strain rate encountered in the realistic machining processes. To address this issue, in this study, we attempt to develop a methodology to understand and identify the plastic deformation behaviors based on high-speed filming and induction preheating during the cutting tests. Different levels of strain, strain rate, and temperature are realized by varying the rake angle, cutting velocity, and initial workpiece temperature, respectively. The plastic deformation and temperature rise in the primary shear zone are characterized by the fine-scale digital image correlation technique and heat convection–conduction equation, respectively, thus rendering the machining test into a high-dynamic-material testing method. The material exhibits strain softening in the primary shear zone and a reduced thermal softening effect under rapid heating conditions. These initial findings can deepen the understanding of material behaviors during the cutting process and can be further developed for implementation in numerical machining models.

Effect of grinding fluid supply on workpiece temperature in continuous generating grinding

Continuous generating grinding (CGG) has been widely used as a highly efficient and precise finishing process for gears. However, due to the significant heat generation, it is necessary to supply a large amount of grinding fluid. Usually more power is consumed by the supplying system than is consumed by the processing machine itself. In industry, unnecessarily large amount of grinding fluid tends to be supplied in CGG since the influence of the supply rate on grinding temperature has not been clarified based on the basic mechanism of grinding fluid action. We have developed an on-site temperature measuring system to directly measure the grinding temperature in CGG. With this system, we were able to capture the instantaneous temperature rise. The effect of the grinding fluid supply on the temperature of the region of removal was investigated by the developed system with different rates of grinding fluid supply as 80 L/min, 140 L/min and 200 L/min. The results showed that increase of grinding fluid supply does not affect the peak temperature. The results indicated that the lubrication effect of grinding fluid was not influenced by the different supply rates in the range of 80 – 200 L/min. In addition, the peak temperature was highly affected by the depth of removal of each abrasive grit. The peak temperature varied since protrusion of each grit on grinding wheel has large variations. In addition to the peak temperature, the integrated temperature was also investigated. The results indicated that the larger amount of grinding fluid was revealed to remove the heat more efficiently in the cooling phase which follows the material removal phase. Eventually we investigated the behavior of the base temperature, which showed that the base temperature is increased when the supply rate was reduced. The overall results indicated that the lubrication effect of grinding fluid was not affected by the supply rate. However, the cooling effect of grinding fluid was affected by the supply rate. The results provided the basic knowledge of the effect of the supply rate of grinding fluid on grinding temperature in CGG, which would contribute to realization of damage-free processes with less amount of supply.

Analytical model of workpiece surface temperature prediction in 4-axis milling process

Milling temperature directly affects surface integrity and fatigue life, which is one of the important physical parameters in the process of machining. At present, the prediction of cutting temperature is mainly focusing on orthogonal cutting and turning; there is little research on the prediction of milling temperature of workpiece. The main idea is to discretize the cutting time and heat source, which is learning from the idea of milling force modeling. The moving heat source method is used to predict the workpiece temperature rise in milling process. The geometric kinematics of five-axis machining motion is analyzed. The temperature rise contribution can be calculated in the shear zone based on orthogonal cutting model through coordinate transformation. The proposed model is verified by experiments and 4-axis milling of cylinder surface temperature field is analyzed by simulation. This method can be extended to the temperature prediction of other processing methods, such as five-axis machining and turn-milling compound machining.

Influence of the Cutting Strategy on the Temperature and Surface Flatness of the Workpiece in Face Milling.

This article analyzes the temperature data obtained for an aluminum alloy face milled using four different cutting strategies. The workpiece temperature was measured at six points with K-type thermocouples. The heat transfer taking place in the cutting zone was also simulated numerically using the finite element method (FEM) and the finite difference method (FDM). The calculation results concerning the distribution of temperature on the workpiece surface were compared with the experimental data. The numerically simulated distribution of temperature on the workpiece surface after face milling was considered in relation to the surface flatness. The findings suggest that the flatness deviations at the workpiece ends were dependent on the depth of cut. Another reason was the cutting strategy selected for the specific thermophysical properties of the workpiece material. Measurement of the workpiece temperature is extremely important because of the thermoelastic behavior and thermal expansion of the material. The isotropic properties of the aluminum alloy make it expand in all directions during milling.

Stabilization of the axisymmetric parts dimensions and shapes

This article reviews the method of increasing the stability of geometrics of non-rigid parts of the “shaft” type. The authors give the grounds for the necessity of treatment by the complex vibro-impact method. The authors also present the unit functional diagram, complete with the automatic control system for the implementation of the proposed method. The unit consists of a self-centering steady rest with a non-flow electrohydraulic drive; a vibro-impact drive with a waveguide converter, a workpiece temperature control device. The control system provides the workpiece axis stabilization and temperature control in the process of axial complex vibro-impacts. The article proves the expediency of using the complex vibro-impact method.

Finite Element Modeling of Hybrid Friction Diffusion Welding of Tube–Tubesheet Joints

AbstractA three-dimensional thermo-mechanical finite element model (FEM) was developed and solved to study the feasibility of hybrid friction diffusion bonding (HFDB) technique for welding tube–tubesheet joints using Abaqus/explicit enviroment. Considering the process thermo-mechanical nature, temperature-dependent material properties and Johnson–Cook model were adopted. Two tube configurations were considered in the numerical study; zero projection (flush) and 3 mm projection (extended). For validation purposes, HFDB of tube–tubesheet was experimentally performed on a 19 mm (¾ in.) ASTM 179 cold-drawn carbon steel tube into ASTM A516-70 tubesheet, considering a flush tube configuration. The tool–workpiece temperature was measured using infrared camera, and produced joints were sectioned and examined under optical microscope. A good agreement was found between numericaly estimated temperatures and material deformation with experimentaly measured ones. According to the estimated results, spring back of tube was found to negatively affect the joint integrity. Also, contact stresses during processing phase were found less in the projected tube (extended) as compared to the flush one.

A comparison of different heat flux density distribution models to predict the temperature in the drilling process

This work aims to improve heat flux distribution models to predict the temperature during drilling. The workpiece temperature is simulated by applying heat flux load only on the hole wall surface. Finite element method is used to simulate the temperature over process time. An iterative identification algorithm using particle swarm optimization (PSO) enables to identify the heat flux distribution parameters through the best fit of the experimental and calculated temperatures. Two heat flux density distributions presented in the literature, namely linear and polynomial, are investigated. A concentrated heat flux distribution is calculated based on measured torque and serves for a comparison purpose. Additionally, the polynomial approach is expanded by adding a concentrated heat flux in order to compensate the lack of hole bottom surface. The best results in terms of residual temperature are obtained for the hybrid heat flow distribution.

A study on the heat affected zone and machining characteristics of difficult-to-cut materials in laser and induction assisted machining

Difficult-to-cut materials are increasingly used to produce products in high-tech automobile, aerospace and other industries. The difficult-to-cut material is excellent in mechanical properties so that conventional machining is difficult. Thermally assisted machining (TAM) is an effective method of machining these difficult-to-cut materials. In TAM, a heat source proceeds the machining tool, which locally preheats and softens the workpiece. Laser assisted machining (LAM) is a typical TAM machining method. While the laser heat source is an excellent preheating method because it directly irradiates the material, it is expensive and the workpiece temperature drops rapidly. Therefore, in recent years, TAM studies using various heat sources other than lasers, such as induction assisted machining (IAM) and plasma assisted machining (PAM) have been carried out. The induction heat source preheats the material using high-frequency current. The laser heat source and induction heat source differ in their preheating method, which has an effect on the heat affected zone and the machining area. In this study, changes in the heat affected zone related to the feed rate of laser and induction heat sources was confirmed. The heat affected zone, preheating temperature and depth of cut of Inconel 718 and Ti-6Al-4 V were investigated through thermal analysis and preheating experiments. In addition, LAM and IAM were performed to compare the machining characteristics such as cutting force and surface roughness according to the feed rate and to verify the effect of improving the machining characteristic.

Correlation of Barreling Effect with Boundary Friction Coefficient during Upsetting of Various Materials Workpieces under Processing Conditions

The necessity of taking into account the barreling effect at the design of die cavities, and open die and closed die forging processes on the basis of pre-forming of billets by upsetting is shown. The division of ideas about the indices of “bulk” and “linear” barreling (barrel shape), which is determined by the ratio of the bulk and linear dimensions of the workpiece after upsetting by flat dies, was made. The functional relation (correlation) between these indices and the friction coefficient on the boundary surface between flat dies and the upsetted workpiece has been determined. The qualitative and quantitative effect of workpiece dimensions (diameter-to-height ratio), strain range, temperature (conditions of cold and hot processing) and type of forming material (structural carbon steel, some of Cu-grades and Al-grades) on the barreling effect and friction coefficient during upsetting was found. The developed method makes it possible to predict a change in the friction coefficient during the upsetting of various material workpiece under given conditions of forming and to monitor their effect to the final shape.

Investigation of the microstructure evolution and properties of A1050 aluminum alloy during radial-shear rolling using FEM analysis

In this study, the analysis of influence temperature-velocity parameters of radial-shear rolling (RSR) on structure and properties of A1050 (Al99.5%) aluminum alloy using the finite element modeling was carried out. During RSR process, the nonuniform change in temperature-velocity parameters occurs in the volume of workpiece. The deformation temperature is one of the main influencing parameters. The gradient of temperature change over section is almost independent of the initial heating temperature of workpiece, and it increases with growth of rotary velocity. In the surface layer, the temperature and strain rate can vary over a wide range due to the deformation temperature and friction on the contact surface. With that, the change in temperature of the rod central zone occurs monotonically and, mainly, due to the energy of plastic deformation. The increasing in strain rate leads to the intense heating of surface layers of workpiece in deformation zone and the decreasing in temperature oscillations between deformation cycles. After RSR the rods with gradient structure and ultrafine surface layer with a microhardness of up to 43 HV were obtained. Depending on the selected temperature-velocity parameters, it is possible to obtain a different combination of mechanical properties (UTS~94…120 MPa; YS~88…110 MPa; δ~1…43.5%). The strength of obtained RSR rods in all regimes is significantly higher than the strength of industrial rods in a hot-pressed condition that shows the application prospect of RSR process as efficient method of controlled plastic deformation of aluminum alloys and obtaining long rods.

Conduction-Based Thermally Assisted Micromilling Process for Cutting Difficult-to-Machine Materials

The increasing demand for complex and wear-resistant forming tools made of difficult-to-machine materials requires efficient manufacturing processes. In terms of high-strength materials; highly suitable processes such as micromilling are limited in their potential due to the increased tool loads and the resulting tool wear. This promotes hybrid manufacturing processes that offer approaches to increase the performance. In this paper; conduction-based thermally assisted micromilling using a prototype device to homogeneously heat the entire workpiece is investigated. By varying the workpiece temperature by 20 °C < TW < 500 °C; a highly durable high-speed steel (HSS) AISI M3:2 (63 HRC) and a hot-work steel (HWS) AISI H11 (53 HRC) were machined using PVD-TiAlN coated micro-end milling tools (d = 1 mm). The influence of the workpiece temperature on central process conditions; such as tool wear and achievable surface quality; are determined. As expected; the temporary thermal softening of the materials leads to a reduction in the cutting forces and; thus; in the resulting tool wear for specific configurations of the thermal assistance. While only minor effects are detected regarding the surface topography; a significant reduction in the burr height is achieved.

Modeling and optimization of flank wear and surface roughness of Monel-400 during hot turning using artificial intelligence techniques

This work aims to model and investigate the effect of cutting speed, feed rate, depth of cut and the workpiece temperature on surface roughness and flank wear (responses) of Monel-400 during turning operation. It also aims to optimize the machining parameters of the above operation. A power-law model is developed for this purpose and is corroborated by comparing the results with the artificial neural network (ANN) model. Based on the coefficient of determination (R2), mean square error (MSE), and mean absolute percentage error (MAPE) the results of the power-law model are found to be in close agreement with that of ANN. Also, the proposed power law and ANN models for surface roughness and flank wear are in close agreement with the experiment results. For the power-law model R2, MSE, and MAPE were found to be 99.83%, 9.9×10-4, and 3.32×10-2, and that of ANN were found to be 99.91%, 5.4×10-4, and 5.96×10-2, respectively for surface roughness and flank wear. An error of 0.0642% (minimum) and 8.7346% (maximum) for surface roughness and 0.0261% (minimum) and 4.6073% (maximum) for flank wear were recorded between the observed and experimental results, respectively. In order to optimize the objective functions obtained from power-law models of the surface roughness and flank wear, GA (genetic algorithm) was used to determine the optimal values of the operating parameters and objective functions thereof. The optimal value of 2.1973 µm and 0.256 mm were found for surface roughness and flank wear, respectively.