Maximum Tool Temperature Research Articles

Modeling of variable friction and heat partition ratio at the chip-tool interface during orthogonal cutting of Ti-6Al-4V

The extreme contact conditions and temperature at the tool-chip interface in machining make it difficult to access the region and evaluate their tribological properties. To overcome this issue, in the author's earlier work, a new ‘pin-on-workpiece’ tribometer was developed that replicates machining tribological conditions and evaluates the velocity-dependent adhesive coefficient of friction (CoF) and heat partition ratio (HPR). In this work, a 2-D finite element model for orthogonal cutting is developed using ABAQUSTM that takes into account the effect of variable CoF and HPR and assesses their effect on cutting forces and temperature. It is observed that as feed rate increases, the location of maximum temperature along chip-tool interface shifts from 1 mm away from the tool-tip, to closer to the tool-tip. Using the variable CoF, the maximum tool temperature reduces to 490 ∘C from 750 ∘C using the constant friction condition. Also, using the variable CoF, the error in cutting force model is reduced to 13 % from 22 % for the constant friction model.

Prediction of specific cutting forces and maximum tool temperatures in orthogonal machining by Support Vector and Gaussian Process Regression Methods

In this paper, machine learning (ML) models, namely Support Vector Regression (SVR) and Gaussian Process Regression (GPR), are presented for the prediction of specific cutting forces and maximum tool temperatures during orthogonal machining processes. The training/test data for building the ML models is generated from finite element (FE) simulations. The simulations are performed using the commercial FE package Abaqus/Explicit and validated using experimental results. The FE generated data consists of cutting speed, uncut chip thickness, and rake angle as the input parameters. The response variables are the cutting force and maximum tool temperature. The data is split into training and test sets using 80-20 split. The optimal SVR and GPR models are selected using grid search on the training data. The predictions on the test data sets show that both the models perform well with high accuracy in predicting cutting force and maximum tool temperature. Between the two models, the mean square errors (MSE) for SVR are less than those for GPR.

Developing Safe Lathing Parameters for PBX 9501

AbstractThis paper presents the work performed on dry‐lathing PBX 9501 to gather and analyze cutting force as well as temperature data during the machining process. The data is compared to present USA federal‐regulation‐constrained machining limits of high explosives. The effects of machining parameters depth of cut, surface meters per minute, and feed per revolution on cutting force and cutting interface were evaluated. Cutting tools of tip radius 0.013 cm and 0.127 cm were tested to determine the effect of the tool shape on the machining process. Empirically, a pronounced dependence of the maximum tool temperature on the depth of cut and surface meters per minute was found, while the dependence on the feed per revolution was found much weaker. It is elucidated that rapid, shallow cuts optimize machining time for a billet of PBX 9501 while minimizing temperature increase and cutting force.

Investigations on tool temperature with heat conduction and heat convection in high-speed slot milling of Ti6Al4V

Tool temperature has significant effects on tool wear and tool life in high-speed machining. Salomon hypothesized that increasing cutting speeds would make tool temperature rise to a maximum point and decrease after a certain cutting speed. However, the maximum tool temperature at a certain cutting speed in Salomon’s hypothesis has not been fully validated and widely accepted by academic researchers and industrial engineers. In this paper, a series of experiments for slot milling of Ti6Al4V alloy at different cutting speeds are carried out and tool insert temperatures are measured. The experimental results indicate that the slot milling tool temperature increases first and then decreases as the cutting speed grows. The critical cutting speed is 1500 m/min for slot milling of Ti6Al4V. To analyze the experimental results and find reasons for the decreased milling tool temperature at high cutting speed, we propose a tool temperature prediction model for slot milling insert. The effects of heat convection and heat conduction time on slot milling tool temperature are analyzed. The finite element method is applied to simulate the heat flux and tool-chip contact length under different uncut chip thicknesses. The simulated heat flux is included in the proposed tool temperature prediction model. The variation of tool temperature in the milling process is affected by heat generation, heat conduction time, and convection coefficient. This research demonstrates that the maximum tool temperature at a certain cutting speed in Salomon’s hypothesis can be accepted for interrupted machining processes.

3D Finite Element Simulation of Micro End-Milling by Considering the Effect of Tool Run-Out

Understanding the micro milling phenomena involved in the process is critical and difficult through physical experiments. This study presents a 3D finite element modeling (3D FEM) approach for the micro end-milling process on Al6082-T6. The proposed model employs a Lagrangian explicit finite element formulation to perform coupled thermo-mechanical transient analyses. FE simulations were performed at different cutting conditions to obtain realistic numerical predictions of chip formation, temperature distribution, and cutting forces by considering the effect of tool run-out in the model. The radial run-out is a significant issue in micro milling processes and influences the cutting stability due to chip load and force variations. The Johnson–Cook (JC) material constitutive model was applied and its constants were determined by an inverse method based on the experimental cutting forces acquired during the micro end-milling tests. The FE model prediction capability was validated by comparing the numerical model results with experimental tests. The maximum tool temperature was predicted in a different angular position of the cutter which is difficult or impossible to obtain in experiments. The predicted results of the model, involving the run-out influence, showed a good correlation with experimental chip formation and the signal shape of cutting forces.

Design of an internally cooled turning tool based on topology optimization and CFD simulation

Cutting fluid is traditionally used to remove the generated heat during the metal cutting process. Employing cutting fluid outside the cutting tools may result in environmental pollution, health hazards, and other significant negative consequences. Internally cooled cutting tools are thus desirable and promising for the machining industry. In this paper, an internally cooled turning tool is designed based on topology optimization and CFD simulation, followed by solid isotropic material with penalization (SIMP) model imported in mechanical and heat conduction analyzing models for the tool flow channel design and optimization. The mechanical and thermal results are utilized on a traditional tool to formulate a sound topology optimization model of the internally cooled tool. In comparison with the performance of the traditional tool, the newly designed one can greatly reduce the heat as well as the maximum temperature with minimum deformation. Key performance of the newly configured tool, including thermal field distribution, best flow speed, maximum cooling capacity and maximum tool temperature, are simulated under different flow speeds by fluid-structure interaction thermal analysis.

Investigation into the role of cooling/lubrication effect of cryogenic minimum quantity lubrication in machining of AISI H13 steel by three-dimensional finite element method

This article developed a three-dimensional finite element model of cryogenic minimum quantity lubrication machining in order to investigate the role of cooling/lubrication effect of cryogenic minimum quantity lubrication in machining of AISI H13 steel. In this model, the cryogenic cooling effect provided by refrigerated compressed air is modeled with a convective heat transfer coefficient. A heat transfer window with the temperature and convective heat transfer coefficient of refrigerated compressed air was defined on tool face and workpiece, respectively, which could move at the same speed as cutting tool so as to simulate continuous cryogenic cooling process of cutting zone under cryogenic minimum quantity lubrication condition. The temperature of refrigerated compressed air was set at −10 °C, −30 °C, −50 °C, −100 °C, and −140 °C to study the influence of cryogenic cooling effect of cryogenic minimum quantity lubrication. Frictional contact between tool and chip was modeled with a simple constant shear stress model. Comparative simulations were conducted under different cooling/lubrication conditions, those are, dry cutting, refrigerated compressed air, and cryogenic minimum quantity lubrication. The simulation results show that both cryogenic cooling effect and lubrication effect resulted in reduction in cutting force and tool temperature when machining AISI H13 steel under cryogenic minimum quantity lubrication condition. With a decrease in temperature of refrigerated compressed air, cutting force and tool temperature did not decrease continuously. The reduction in cutting force, maximum tool temperature, and average temperature of rake face and flank face at low and high cutting speeds was strongly attributed to the cryogenic cooling effect and lubrication effect provided by cryogenic minimum quantity lubrication, respectively. A significant reduction in cutting force and tool temperature was caused by the improvement in lubrication effect provided by cryogenic minimum quantity lubrication irrespective of the cutting speed. The trends revealed by the simulations provide helpful information for the development of this technique.

Three-Dimensional Finite Element Simulation of Cylindrical Turning of Titanium Alloys

The understanding of cutting mechanism is important for the improvement of machinability of difficult-to-cut materials. Finite element method (FEM) is an effective way to study the metal cutting process. This paper establishes a finite element model of cylindrical turning of titanium alloys, and then simulates cutting force and tool temperature distribution under different cutting parameters. The simulation results show that in the high-speed cylindrical turning of titanium alloys, depth of cut has a greater influence on principal cutting force than feed rate, while the effect of feed rate on the maximum tool temperature is more distinct than that of depth of cut.

Numerical simulation of orthogonal machining process using multilayer and single-layer coated tools

In this study, numerical simulation was carried out to determine the effect of coating type on the cutting forces, tool stresses, and temperatures. The Lagrangian thermo-viscoplastic cutting simulation of AISI 4340 steel was conducted using two different coating types (TiCN + Al2O3 + TiN and Al2O3) and uncoated carbide tool having same geometry. Johnson–Cook work material model is used for plastic deformations. The predicted cutting forces for the coated and uncoated tools were compared with the experimental results. The variation of tool stress and temperature with coating type and number of coating layer were investigated. The predicted results indicated that the tool coated with Al2O3 showed minimum tool temperature value due to its decreasing thermal conductivity with increasing temperature. Maximum tool temperature occurs at the rake surface of the cutting tools (coated and uncoated) and decreases rapidly with depth in the coated tools. On the other hand, the tool stress within the coating increases along the thickness with increasing cutting speed and feed rate. Minimum shear angle is observed in uncoated carbide tool whereas maximum shear angle occurs for Al2O3-coated tool. This result also confirms the results obtained from cutting tests.

FEM analysis of edge preparation for chamfered tools

The chamfer enhances the performance of the tool by strengthening the edge and reducing the possibility of tool wear and breakage. The strength of the chamfered tool can be investigated by analysis of process variables. This research investigates the effects of chamfer width and chamfer angle on process variables (force, stress, tool temperature and tool stress) in machining of a mild carbon low alloy steel by a cemented carbide tool using finite element method. The simulations show that the dead metal zone created under the tool acts as the effective cutting edge of the tool and increases the cutting forces. The predicted results show that the effect of chamfer width and angle is more pronounced on the thrust force than the cutting force. It also investigates the effect of chamfer on the effective shear angle and chip thickness, and comparison with available experimental results is presented. Tool temperatures are also predicted which suggests the presence of an optimum chamfer angle from the viewpoint of maximum tool temperature.

Temperature Measurement of Cutting Edge in Drilling -Effect of Oil Mist-

In drilling, the temperature of the cutting edges of a drill is measured using a two-color pyrometer with an optical fiber. A cemented carbide drill with a diameter of 10 mm is used as a cutting tool, and carbon steel, cast iron and aluminum die-cast alloy are used as work materials. The temperature distribution along the cutting edge of a drill is measured and the influence of spindle speed and feed rate on the tool temperature is investigated. The maximum tool temperature is observed during the drilling of carbon steel. The effect of oil mist supplied from oil holes in the drill on the tool temperature is examined and the result is compared to that in turning and end milling. The temperature reduction in oil mist turning is approximately 5%, while in oil mist end milling it is 10–15% and that in oil mist drilling is 20–25% compared to the temperature in dry cutting.

Progressive tool-wear in machining with coated grooved tools and its correlation with cutting temperature

This paper presents a detailed analysis of tool-wear progression through an experimental study of orthogonal machining of AISI 1045 steel with coated (TiN/TiCN/TiC) grooved tools. Transient infrared temperature measurements during the orthogonal cutting process have been obtained along with measurement of corresponding progressive tool-wear when turning using coated grooved tools under dry machining conditions. Simultaneously, two cutting force components were also recorded. The results obtained enabled the understanding of the modes of tool-wear, and helped to verify the effects of tool-chip interfacial temperature. This time-dependent study of tool-wear with the concurrent tool-chip interface temperature distributions reveals the relationship between the maximum tool temperature and the location of the maximum tool-wear rate at any given point in time. Scanning electron microscopic (SEM) analysis clearly shows the different dominant wear regions at different stages of machining with coated grooved tools. In this study, concurrent progression of flank wear (VB), secondary wall wear (SW, SD), and groove backwall wear (BW, KT) are examined. Finally, interrelationships between the progressive tool-wear, cutting temperature and the cutting forces are established experimentally, providing a framework for further studies.

Heat transfer and life of metal cutting tools in turning

An experimental study is performed using both thermocouples and infrared thermovision to monitor timewise temperature variations of the tool and workpiece in orthogonal cutting. A semi-empirical formula is derived to express the temperature-time history of the tool surface, using a local element lumped conduction equation with experimental data-fitting. Infrared thermovision identifies the location of the maximum tool temperature slightly inward from the cutting edge. An optical and electronic microscope reveals the formation of micropits, the origin of flank and rake wear that originates in the region of surrounding the maximum tool temperature. It is disclosed that the progression of wears is accompanied by a consistent increase in the tool temperature which in turn accelerates the wearing process. Chip geometry is found to affect local steady-state temperatures in the cutting tool. For cast iron and copper, chip geometry may causes a zig-zag variation in the steady-state temperature with respect to the rate of material removal for a change in the feed. The study sheds light on the causes of roughness of surfaces cut with a hard tool and may thus serve as the first step in the investigation of surface machining.