A Two-Dimensional Transient Thermal Model for Coated Cutting Tools

Author(s):  
Coskun Islam ◽  
Yusuf Altintas

Prediction of temperature in the tool, chip, and workpiece surface is important to study tool wear, residual stresses in the machined part, and to design cutting tool substrates and coating. This paper presents a finite difference method-based prediction of temperature distribution in the tool, chip, and workpiece surface for transient conditions. The model allows inclusion of anisotropic materials such as coating or different material properties. The energy is created in the primary shear zone where the metal is sheared, the secondary deformation zone where the chip moves on the tool rake face with friction, and the tertiary zone where the flank face of the tool rubs against the finished part surface. The model allows both sticking and sliding friction contact of the moving chip on the rake face of the tool. The distribution of temperature is evaluated by meshing chip, workpiece surface zone, and tool into small discrete elements. The heat transfer among the elements is modeled, and the temperature is predicted at the center of each element. The heat transfer to the tool, workpiece, and chip is iteratively evaluated. The predicted temperature values are compared against the experimental measurements collected with coated tools in turning.

2013 ◽  
Vol 652-654 ◽  
pp. 2105-2108
Author(s):  
Xu Xing Jin

Mar-M247 is widely used in industry for its excellent mechanical properties at high temperatures, but it has the shortcoming of difficulty manufactured. In order to obtain the cutting characteristics of Mar-M247, firstly, an end milling experiment was set up accordingly, where three types of cutting tools coated respectively by TiN, TiCN and TiAlN were employed. Then the parameters of cutting speed and feed rate were defined as the tool cutting variables. Finally, based on different cutting variables, the performance of tool wear, tool life, and workpiece surface roughness were analyzed and discussed. The results indicate when the tool coated by TiAlN, cutting speed of range 1600 ~ 3200 rpm and feed rate of range 0.06 ~ 0.08 mm / tooth are chosen together, the integrated states manufactured of the tool and the workpiece would be best, the method of this research can provide some references for studying others Nickel-based superalloys.


2021 ◽  
Author(s):  
Jingjie Zhang ◽  
Zhanqiang Liu ◽  
Chonghai Xu ◽  
Jin Du ◽  
Guosheng Su ◽  
...  

Abstract The coating effect on the cutting temperature has long been a hot topic in understanding heat transfer mechanism in machining coated tools, and especially the multi-layer coated tools. For multi-layer coated tools, the coating structure, coating thickness and coating material will affect the cutting temperature of the tool. This paper is devoted to the cutting temperature in dry turning of H13 hardened steel with multi-layer coatings. New analytical models for estimating coating temperature and coating-substrate interface temperature were proposed. The multi-layer coating can be equivalent to mono-layer composite coating, which applies equivalent coating layer approach, and was developed to estimate the cutting temperature in turning by heat transfer model of mono-layer coated tool. The analyzed results were compared to appropriate experimental process data using thermocouples and FEM simulated data. The models were verified can accurate temperature under the same cutting conditions for two multi-layer coated tools.


Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1783
Author(s):  
Hamza A. Al-Tameemi ◽  
Thamir Al-Dulaimi ◽  
Michael Oluwatobiloba Awe ◽  
Shubham Sharma ◽  
Danil Yurievich Pimenov ◽  
...  

Aluminum alloys are soft and have low melting temperatures; therefore, machining them often results in cut material fusing to the cutting tool due to heat and friction, and thus lowering the hole quality. A good practice is to use coated cutting tools to overcome such issues and maintain good hole quality. Therefore, the current study investigates the effect of cutting parameters (spindle speed and feed rate) and three types of cutting-tool coating (TiN/TiAlN, TiAlN, and TiN) on the surface finish, form, and dimensional tolerances of holes drilled in Al6061-T651 alloy. The study employed statistical design of experiments and ANOVA (analysis of variance) to evaluate the contribution of each of the input parameters on the measured hole-quality outputs (surface-roughness metrics Ra and Rz, hole size, circularity, perpendicularity, and cylindricity). The highest surface roughness occurred when using TiN-coated tools. All holes in this study were oversized regardless of the tool coating or cutting parameters used. TiN tools, which have a lower coating hardness, gave lower hole circularity at the entry and higher cylindricity, while TiN/TiAlN and TiAlN seemed to be more effective in reducing hole particularity when drilling at higher spindle speeds. Finally, optical microscopes revealed that a built-up edge and adhesions were most likely to form on TiN-coated tools due to TiN’s chemical affinity and low oxidation temperature compared to the TiN/TiAlN and TiAlN coatings.


2011 ◽  
Vol 03 (01n02) ◽  
pp. 91-107 ◽  
Author(s):  
JÜRGEN LEOPOLD ◽  
KATRIN HELLER ◽  
ARNDT MEYER ◽  
REINER WOHLGEMUTH

The stability of coating-substrate systems influences the chip formation and the surface integrity of the new generated workpiece surface, too. Using finite element (FE) simulation, deformations, strains and stresses in coated tools, caused by external and internal loads, can be computed on a microscopic scale. Since both, the whole macroscopic tool (in mm-scale) and the microscopic coating layers (in μm-scale up to nm-scale) must be included in the same geometrical simulation model, graded high-resolution FE meshes must be used. Nevertheless, the number of nodes in the 3D computational FE grid reaches some millions, leading to large computational time and storage requirements. For this reason, an advanced adaptive finite element (AAFEM) software has been developed and used for the simulation.


Lubricants ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 98 ◽  
Author(s):  
Zhengyang Kang ◽  
Yonghong Fu ◽  
Xingyu Fu ◽  
Martin Jun

In recent years, surface texturing in micro-scale has been attempted on the surface of cutting tools for multiple purposes, e.g., cutting force reduction, prolonging life-span, anti-adhesion, etc. With respect to machinability and performance, micro-groove texture (MGT) has dominated in this field compared to other textured patterns. In this study, a novel volcano-like texture (VLT) was fabricated on the rake face of cemented carbide inserts (WC-Co, YG6) by fiber laser. The following cutting experiment tested the flat, MGT and VLT tools in turning aluminum alloy 6061. The effects of coolant and cutting conditions were investigated. In addition, a validated FEM model was employed to explore the distribution of stress and temperature fields in the tool-chip interface. The initial forming process of adhesion layer on rake face was investigated as well. The results indicated that lower cutting force and less adhesion can be achieved by small scale VLT. This study not only introduced VLT on cutting tools but also revealed its comprehensive performance.


1979 ◽  
Vol 101 (2) ◽  
pp. 97-103 ◽  
Author(s):  
Y. Saito ◽  
N. Nishiwaki ◽  
Y. Ito

The thermal boundary condition around the workpiece surface is one of important factors to analyze the thermal deformation of a workpiece, which is in close relation to the machining, accuracy of grinding. The heat dissipation from the workpiece surface which is influenced by the flow pattern, may govern this thermal boundary condition. In consequence, it is necessary to clarify the convection heat transfer coefficient and the flow pattern of air and/or grinding fluid around surroundings of a rotating grinding wheel and of a workpiece. Here experiments were carried out in a surface grinding process to measure the flow velocity, wall pressure and local heat transfer by changing the porosity of the grinding wheel. The air blowing out from the grinding wheel which is effected by the porosity may be considered to have large influences on the local heat transfer coefficient, which is found to be neither symmetric nor uniform over the workpiece surface.


Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1515
Author(s):  
Jinxing Wu ◽  
Lin He ◽  
Yanying Wu ◽  
Chaobiao Zhou ◽  
Zhongfei Zou ◽  
...  

Tool-chip friction increases cutting temperature, aggravates tool wear, and shortens the service life of cutting tools. A micro-groove design of the rake face can improve the wear performance of the tool. In this study, we used the finite element simulation “Deform” to obtain the temperature field distribution of the tool rake face. The size of the micro-groove was determined by selecting a suitable temperature field combined with the characteristics of tool–chip flow in the cutting process, and the tool was prepared using powder metallurgy. The three-direction cutting forces and tool tip temperature were obtained by a cutting test. Compared with the original turning tool, the cutting force and cutting temperature of the micro-groove tool were reduced by more than 20%, the friction coefficient was reduced by more than 14%, the sliding energy was reduced and the shear energy was greatly decreased. According to the analysis of tool wear by SEM (scanning electron microscope) and EDS (energy dispersive X-ray spectroscopy), the crater wear, adhesive wear and oxidation wear of the micro-groove tool were lower than those of the original turning tool. In particular, the change in the crater wear area on the rake face of the original tool and the micro-groove tool was consistent with the cutting temperature and the wear width of the flank face. On the whole, the crater wear area and the change rate of the crater wear area of the micro-groove tool were smaller. Due to the proper microgroove structure of the rake face, the tool-chip contact area decreased, and the second rake angle of the tool became larger. Hence, the tool-chip friction, cutting forces, cutting energy consumption were reduced, tool wear was improved, and the service life of the micro-groove tool was five times longer than that of the original tool.


Author(s):  
Xiuying Ni ◽  
Jun Zhao ◽  
Feng Gong ◽  
Gang Li

The major concern of this article is the fatigue failure mechanisms of ceramic cutting tools with the help of intermittent turning experiment and simulation. Finite element simulation was adopted to analyze the spatial and temporal distribution of the stress on the cutting tools. The crack initiation and expansion life in the different positions was researched based on the fatigue crack model. The experiment results showed that the fracture area of flank face reduced with the increase in feed rates, while the fracture area and damage depth of rake face both increased. Through the simulation of fatigue crack, it could be inferred that fatigue fractures were caused by coalescence of cracks. When the feed rate was greater than or equal to 0.2 mm, tool failure was mainly manifested as fatigue fracture of the rake face. And the results of fatigue crack propagation simulation well predicted the cutting tool life. A novel research method for tool fatigue failure was provided.


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