Turning inserts the selection approach based on fuzzy comprehensive evaluation

Tool selection is a multi-criteria decision-making problem in the presence of various selection criteria and a set of alternatives, but previous works are limited to evaluating the tools within the workshop tool library. To intelligently select proper inserts across suppliers under the Internet environment, an insert data format based on ISO 513 was established, and a framework was then designed to obtain a set of alternatives from different suppliers based on fuzzy intervals. Then, knowledge was described with convenient language and the simple membership function to build an intelligent system, which would infer the matching degree of insert characteristics to the machining conditions. Furthermore, analytic hierarchy process was applied to sort the alternatives. Finally, the case study shows that compared with previous works and machinists, this work not only obtains a set of alternatives from all suppliers who uploaded their product data with the designed format but comprehensively evaluates the insert (take finishing low-carbon steel as an example, both cemented carbide and cermet are recommended, the nose radius reduces 25%, the environmental index increases 25%, while the rake reduces 11.25%, when compared with machinists who tend to select the larger rake angle foe finishing). A platform was also developed based on Visual Studio 2015 and SQL Server 2012 to improve selection efficiency for inexperienced CNC operators, purchasers, and vendors.

Fracture energy for orthogonal cutting in unidirectional CFRP at different cutting directions

A unidirectional carbon fibre reinforced polymer (CFRP) laminate is a composite material made up of strong parallel carbon fibres incorporated in a polymer matrix such as epoxy to provide high stiffness and strength in the fibre direction of the laminate. Unfortunately, the interlaminar or intralaminar plane of this material has a low resistance to damages as the fracture toughness of a unidirectional CFRP laminate is related to the energy dissipation during the orthogonal cutting. The aim of this study is on cutting a unidirectional CFRP along the longitudinal or transverse directions, characterizing orthogonal cutting forces and the related fracture energy. Orthogonal cutting is performed using braised carbide tools for a range of cutting depth of 10-100 ³m with a rake angle of 30° to quantify the cutting forces and to observe the fracture mechanisms. The fibre orientations have a significant impact on surface bouncing-back. For some fibre orientations, the energy balance model is applicable, deducting the reasonable value of fracture toughness due to high normal force (F t). Fibre subsurface damage and cutting forces during cutting are found to be strongly influenced by the cutting depth. The input energy of cutting is released in form of new surface energy, fibre breakage, high bending energy, and chip fracture energy.

Predictive Analytical Modeling of Thermo-Mechanical Effects in Orthogonal Machining

Factor relationships in a machining system do not work in pairs. Varying the cutting parameters, materials machined, or volumes produced will influence many machining characteristics. For this reason, we are attempting to better understand the effect of the Johnson-Cook (J-C) law of behavior on cutting temperature prediction. Thus, the objective of the present study is to investigate, experimentally and theoretically, the tool/material interactions and their effects on dust emission during orthogonal cutting. The proposed approach is built on three steps. First, we established an experimental design to analyze, experimentally, the cutting conditions effects on the cutting temperature under dry condition. The empirical model which is based on the response surface methodology was used to generate a large amount of data depending on the machining conditions. Through this step, we were able to analyze the sensitivity of the cutting temperature to different cutting parameters. It was found that cutting speed, tool tip radius, rake angle, and the interaction between the cutting speed and the rake angle explain more than 84.66% of the cutting temperature variation. The cutting temperature will be considered as a reference to validate the analytical model. Hence, a temperature prediction model is important as a second step. The modeling of orthogonal machining using the J-C plasticity model showed a good correlation between the predicted cutting temperature and that obtained by the proposed empirical model. The calculated deviations for the different cutting conditions tested are relatively acceptable (with a less than 10% error). Finally, the established analytical model was then applied to the machining processes in order to optimize the cutting parameters and, at the same time, minimize the generated dust. The evaluation of the dust generation revealed that the dust emission is closely related to the variation of the cutting temperature. We also noticed that the dust generation can indicate different phenomena of fine and ultrafine particles generation during the cutting process, related to the heat source or temperature during orthogonal machining. Finally, the effective strategy to limit dust emissions at the source is to avoid the critical temperature zone. For this purpose, the two-sided values can be seen as combinations to limit dust emissions at the source.

MEASUREMENT OF THE GEOMETRY OF MANUFACTURED DRILLS USING OPTICAL SCANNING

This article deals with the control of the geometry of manufactured tools. The geometry of the cutting tool has a great influence on the machining process. One of the processes of manufacturing cutting tools is grinding. Grinding cutting tools is a complex process after which it is necessary to check the geometry of the tools. Five solid drilling tools were manufactured for the experiment. The measured parameters were tool diameter, helix angle, point angle, rake angle, relief angle and core diameter of the cutting tools. The geometry of the cutting tools was measured on a non-contact structured 3D scanner ATOS Triple Scan light. The measurement results were evaluated using GOM software. The scanning results were compared with the geometry measurement on an optical measuring device Zoller Genius 3s. It has been found that the use of a non-contact structured 3D scanner is suitable for checking the geometry of cutting tools. Furthermore, the article deals with the roughness arising when grinding a sintered carbide flute.

Enhancing Wear Resistance and Cutting Performance of a Long-Life Micro-Groove Tool in Turning AISI 201

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.

Numerical simulation of the influence of tool geometry on energy consumption during micro turning of titanium alloy

Fabrication of an axisymmetric biomedical implant with good dimensions, form and surface integrity features are a challenging task in the micro-manufacturing industry. This is due to workpiece deflection, vibrations, tool wear and adhesion of the chip on the cutting inset during the micromachining process. So experimental evaluation on the variation of tool geometry is expensive and difficult as stated in prior literature. So, in this work, a finite-element method simulation is developed to comprehend the physics of the process and predict the energy consumption by incorporating the effect of material strengthening caused by shearing of material across the grain, shear band pattern upon strain rate and tool geometry such as edge radius, nose radius and rake angle. The modified Johnson-Cook material model is used to state the flow stress and an adaptive remeshing technique is utilized to model the plastic deformation at a higher strain rate during the simulation process. Initially, the model is developed in a transient state and then modified to a steady-state to obtain the output process parameters. The proposed model is calibrated and validated with experimental results reported in the literature. It is inferred that the cutting force, thrust force and feed force acquired from finite-element method simulation have been confirmed experimentally with prediction accuracy of 94%, 82.66% and 87.02%, respectively. It is also inferred that energy consumption during machining reduces with an increase in rake angle because of the sharpness of the cutting edge and less friction between tool and chip. An increase of nose radius and edge radius produces high thrust force and energy consumption and impedes high radial depth of cut. For the same machining parameters with the increase of edge radius and decrease of rake angle the mechanism of material removal changes from shearing to ploughing.

Multi-objective Optimization of Turning Tool Geometric Parameters Based on Kriging Model

Cutting performance parameters of turning tool in different geometric parameters are obtained using finite element model, and the Kriging models of cutting stress and temperature are constructed, taking the cutting performance parameters as training samples. The multi-objective optimization model of turning tool geometric parameters is established based on the constructed cutting performance Kriging models, in which the design variables are rake angle, relief angle and cutting-edge radius, the objective parameters are cutting stress and temperature. The multi-island genetic algorithm is used to obtain the optimum turning tool geometric parameters: rake angle γo is 10.59°, relief angle λs is 6.15°and cutting-edge radius γE is 0.73mm. The simulation results after optimization demonstrate that the corresponding cutting temperature reduces 263.1°C, cutting stress drops by 550.8MPa.

Finite Element Modeling of Brittle and Ductile Modes in Cutting of 3C-SiC

Machining of brittle ceramics is a challenging task because the requirements on the cutting tools are extremely high and the quality of the machined surface strongly depends on the chosen process parameters. Typically, the efficiency of a machining process increases with the depth of cut or the feed rate of the tool. However, for brittle ceramics, this easily results in very rough surfaces or even in crack formation. The transition from a smooth surface obtained for small depths of cut to a rough surface for larger depths of cut is called a brittle-to-ductile transition in machining. In this work, we investigate the mechanisms of this brittle-to-ductile transition for diamond cutting of an intrinsically brittle 3C-SiC ceramic with finite element modeling. The Drucker–Prager model has been used to describe plastic deformation of the material and the material parameters have been determined by an inverse method to match the deformation behavior of the material under nanoindentation, which is a similar loading state as the one occurring during cutting. Furthermore, a damage model has been introduced to describe material separation during the machining process and also crack initiation in subsurface regions. With this model, grooving simulations of 3C-SiC with a diamond tool have been performed and the deformation and damage mechanisms have been analyzed. Our results reveal a distinct transition between ductile and brittle cutting modes as a function of the depth of cut. The critical depth of cut for this transition is found to be independent of rake angle; however, the surface roughness strongly depends on the rake angle of the tool.

Optimization Method of Tool Parameters and Cutting Parameters Considering Dynamic Change of Performance Indicators

In the process of metal cutting, the cutting performance of cutting tools varies with different parameter combinations, so the results of the performance indicators studied are also different. So in order to achieve the best performance indicator it is necessary to get the best parameter matching combination. In addition, in the process of metal cutting, the value of the performance index is different at each stage of the processing process. In order to consider the cutting process more comprehensively, it is necessary to use a comprehensive evaluation method that can evaluate the dynamic process of performance indicators. This paper uses a dynamic evaluation method that considers the dynamic change of performance indicators in each stage of the cutting process to comprehensively evaluate the tool parameters and cutting parameters at each level. For the purpose of high processing efficiency and long tool life, tool wear rate and material removal rate are used as performance indicators. In the case of specified rake angle, cutting speed and cutting width, titanium alloy is studied by end milling cutter side milling. The tool parameters and cutting parameters in milling process are optimized by using a dynamic comprehensive evaluation method based on gain horizontal excitation. Finally, the parameter matching combination that can make the performance indicator reach the best is obtained. The results show that when the rake angle is 8°, the cutting speed is 37.68 m/min, and the cutting width is 0.2 mm, the tool wear rate and material removal rate are the best when the clearance angle is 9°, the helix angle is 30°, the feed per tooth is 0.15 mm/z, and the cutting depth is 2.5 mm.

Technical and technological factors’ effects on quality of the machined surface and energetic efficiency when planar milling heat-treated meranti wood

As heat-treated wood has an ever-increasing application, the research of its machining is the subject of many studies. This article investigated the technical, technological, material, and tool-related factors that influence the quality of the machined surface (average roughness Ra) and energy consumption during the process of planar milling of heat-treated meranti wood. The experimental measurements were performed on samples that were treated by four methods at temperatures of 160 °C, 180 °C, 200 °C, and 220 °C. One sample was in its natural state. The cutting conditions were as follows: feed rates 6 m × min-1, 10 m × min-1, and 15 m × min-1, cutting speeds of 20 m × s-1, 40 m × s-1, and 60 m × s-1, and tool rake angles of 20°, 25°, and 30°. Experimental measurement of the surface roughness was performed using an LPM – 4 profilometer. Individual measurements of cutting power were performed via a frequency converter. The experiments determined the effects of the individual parameters on surface roughness in the following order: rake angle, heat treatment of the material, feed rate, and cutting speed. The effects of observed parameters on energetic efficiency were in the order: cutting speed, feed rate, rake angle, and heat treatment.