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Showing papers in "International Journal of Machine Tools & Manufacture in 2001"


Journal ArticleDOI
TL;DR: In this paper, a quintic spline trajectory generation algorithm was proposed to generate continuous position, velocity, and acceleration profiles. But the spline interpolation is realized with a novel approach that eliminates feedrate fluctuations due to parametrization errors, resulting in trapezoidal acceleration profiles along the toolpath.
Abstract: Reference trajectory generation plays a key role in the computer control of machine tools. Generated trajectories must not only describe the desired tool path accurately, but must also have smooth kinematic profiles in order to maintain high tracking accuracy, and avoid exciting the natural modes of the mechanical structure or servo control system. Spline trajectory generation techniques have become widely adopted in machining aerospace parts, dies, and molds for this reason; they provide a more continuous feed motion compared to multiple linear or circular segments and result in shorter machining time, as well as better surface geometry. This paper presents a quintic spline trajectory generation algorithm that produces continuous position, velocity, and acceleration profiles. The spline interpolation is realized with a novel approach that eliminates feedrate fluctuations due to parametrization errors. Smooth accelerations and decelerations are obtained by imposing limits on the first and second time derivatives of feedrate, resulting in trapezoidal acceleration profiles along the toolpath. Finally, the reference trajectory generated with varying interpolation period is re-sampled at the servo loop closure period using fifth order polynomials, which enable the original kinematic profiles to be preserved. The proposed trajectory generation algorithm has been tested in machining a wing surface on a three axis milling machine, controlled with an in house developed open architecture CNC.

519 citations


Journal ArticleDOI
TL;DR: In this paper, a micro-nozzle was proposed to inject focused liquid nitrogen into the chip-tool interface at the point of highest temperature to lower the coefficient of friction between the chip and the tool.
Abstract: Titanium alloy Ti-6Al-4V, a difficult-to-machine material because of its extremely short tool life, has been a major subject for cryogenic machining research. However, the approaches reported in past publications are inherently flawed. This study reviews how the temperature affects Ti-6Al-4V properties, and compares different cryogenic cooling strategies. Based on these findings, a new economical cryogenic cooling approach is proposed. Using a minimum amount of liquid nitrogen (LN2), this innovation features a specially designed micro-nozzle. Formed between the chip breaker and the tool rake face, the nozzle lifts the chip and injects focused LN2 into the chip–tool interface at the point of highest temperature. As the nitrogen evaporates, a nitrogen cushion formed by evaporating nitrogen lowers the coefficient of friction between the chip and the tool. An auxiliary mini-nozzle that sprays LN2 onto the flank at the cutting edge further reduces the cutting temperature. The study finds that the combination of these two micro-nozzles provides the most effective cooling while using the lowest LN2 flow rate. Improving the position of the nozzle/chip breaker further enhances the performance. Our cryogenic machining tests show that tool life increases up to five times the state-of the-art emulsion cooling, outperforming other machining approaches.

407 citations


Journal ArticleDOI
TL;DR: In this article, liquid nitrogen (LN2) is applied to cutting Ti-6Al-4V, a difficult-to-machine but widely used material in aerospace industry.
Abstract: Cryogenic machining is an environmentally safe alternative to conventional emulsion cooling. In this study, liquid nitrogen (LN2) is applied to cutting Ti-6Al-4V, a difficult-to-machine but widely used material in aerospace industry. With the goal of identifying the cooling approach for most effectively and economically using cryogenic machining, this study evaluated cutting temperatures obtained under various cooling conditions. In addition to analyzing cooling approaches reported in previous cryogenic machining literatures (i.e., precooling the workpiece and conductive remote cooling), this paper introduces an innovative and economical dispensing method that directs LN2 through micro jets to the flank, the rake, or both near the cutting edge. The cutting temperatures were theoretically estimated by finite element method and the influence of cutting speed was analyzed. They were experimentally verified using the thermocouple imbedded at the carbide insert. Temperatures in cryogenic machining were compared with conventional dry cutting and emulsion cooling. Findings showed that a small amount of liquid nitrogen applied locally to the cutting edge is superior to emulsion cutting in lowering the cutting temperature. The study found that cooling approaches in order of effectiveness (worst to best) to be: dry cutting, cryogenic tool back cooling, emulsion cooling, precooling the workpiece, cryogenic flank cooling, cryogenic rake cooling, and simultaneous rake and flank cooling.

367 citations


Journal ArticleDOI
TL;DR: In this article, a generalized mathematical model of most helical end mills used in the industry is presented, where the end mill geometry is modeled by helical flutes wrapped around a parametric envelope.
Abstract: A variety of helical end mill geometry is used in the industry. Helical cylindrical, helical ball, taper helical ball, bull nosed and special purpose end mills are widely used in aerospace, automotive and die machining industry. While the geometry of each cutter may be different, the mechanics and dynamics of the milling process at each cutting edge point are common. This paper presents a generalized mathematical model of most helical end mills used in the industry. The end mill geometry is modeled by helical flutes wrapped around a parametric envelope. The coordinates of a cutting edge point along the parametric helical flute are mathematically expressed. The chip thickness at each cutting point is evaluated by using the true kinematics of milling including the structural vibrations of both cutter and workpiece. By integrating the process along each cutting edge, which is in contact with the workpiece, the cutting forces, vibrations, dimensional surface finish and chatter stability lobes for an arbitrary end mill can be predicted. The predicted and measured cutting forces, surface roughness and stability lobes for ball, helical tapered ball, and bull nosed end mills are provided to illustrate the viability of the proposed generalized end mill analysis.

345 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated how the friction between the chip and the tool is affected by focused jetting LN2 to the cutting point in machining Ti-6Al-4V.
Abstract: Conventional cutting fluid serves both as a coolant and lubricant. In cryogenic machining, liquid nitrogen (LN2) is recognized as an effective coolant due to its low temperature; however, its lubrication properties are not well known. The focus of this study was to investigate how the friction between the chip and the tool is affected by focused jetting LN2 to the cutting point in machining Ti–6Al–4V. Results of cutting force measurements indicated that the cold strengthening of titanium material increased the cutting force in cryogenic machining, but lower friction reduced the feed force. A mathematical model was developed to convert the measured 3D forces in oblique cutting into the normal and frictional force components on the tool rake face, and then to calculate the effective friction coefficient. It was found that the friction coefficient on the tool–chip interface was considerably reduced in cryogenic machining. Increased shear angle and decreased thickness of the secondary deformation zone, findings from a chip microstructure study, offer further evidence that friction is reduced.

253 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigate the mechanisms of chip formation for a Ti-6Al-4V alloy and assess the influences of such on acoustic emission (AE) within the range of conditions employed (cutting speed, v c = 0.25-3.0 m/s, feed, f=20-100 μm ).
Abstract: Orthogonal cutting tests were undertaken to investigate the mechanisms of chip formation for a Ti–6Al–4V alloy and to assess the influences of such on acoustic emission (AE). Within the range of conditions employed (cutting speed, v c =0.25–3.0 m/s , feed, f=20–100 μm ), saw-tooth chips were produced. A transition from aperiodic to periodic saw-tooth chip formation occurring with increases in cutting speed and/or feed. Examination of chips formed shortly after the instant of tool engagement, where the undeformed chip thickness is slightly greater than the minimum undeformed chip thickness, revealed a continuous chip characterised by the presence of fine lamellae on its free surface. In agreement with the consensus that shear localisation in machining Ti and its alloys is due to the occurrence of a thermo-plastic instability, the underside of saw-tooth segments formed at relatively high cutting speeds, exhibiting evidence of ductile fracture. Chips formed at lower cutting speeds suggest that cleavage is the mechanism of catastrophic failure, at least within the upper region of the primary shear zone. An additional characteristic of machining Ti–6Al–4V alloy at high cutting speeds is the occurrence of welding between the chip and the tool. Fracture of such welds appears to be the dominant source of AE. The results are discussed with reference to the machining of hardened steels, another class of materials from which saw-tooth chips are produced.

252 citations


Journal ArticleDOI
TL;DR: In this paper, the friction model is developed by observing the disturbance torque through a Kalman filter, while jogging the axes under closed loop control at various speeds, and the overall axis model is used in designing a high speed feed drive control system, which has been presented in Part III.
Abstract: Accurate modeling and identification of the feed drives' dynamics is an important step in designing a high performance CNC. This paper presents a method for identifying the dynamic parameters, as well as the friction characteristics of machine tool drives. The inertia and viscous friction are estimated through an unbiased least squares scheme. The friction model is developed by observing the disturbance torque through a Kalman filter, while jogging the axes under closed loop control at various speeds. The overall axis model is used in designing a high speed feed drive control system, which has been presented in Part III of this paper. As verification of the identified friction model, contouring test results without and with friction compensation are also presented.

246 citations


Journal ArticleDOI
TL;DR: Comparisons on predictions of surface finish for various work materials with the change of electrode polarity based upon six different neural-networks models and a neuro-fuzzy network have been illustrated and it is concluded that the further experimental results have agreed to the predictions based upon the above four models.
Abstract: Predictions on the surface finish of work-pieces in electrical discharge machining (EDM) based upon physical or empirical models have been reported in the past years. However, when the change of electrode polarity has been considered, very few models have given reliable predictions. In this study, the comparisons on predictions of surface finish for various work materials with the change of electrode polarity based upon six different neural-networks models and a neuro-fuzzy network model have been illustrated. The neural-network models are the Logistic Sigmoid Multi-layered Perceptron (LOGMLP), the Hyperbolic Tangent Sigmoid Multi-layered Perceptron (TANMLP), the Fast Error Back-propagation Hyperbolic Tangent Multi-layered Perceptron (Error TANMLP), the Radial Basis Function Networks (RBFN), the Adaptive Hyperbolic Tangent Sigmoid Multi-layered Perceptron, and the Adaptive Radial Basis Function Networks. The neuro-fuzzy network is the Adaptive Neuro-Fuzzy Inference System (ANFIS). Being trained by experimental data initially screened by the Design of Experiment (DOE) method, the parameters of the above models have been optimally determined for predictions. Based upon the conclusive results from the comparisons on checking errors among these prediction models, the TANMLP, RBFN, Adaptive RBFN, and ANFIS model have shown consistent results. Also, it is concluded that the further experimental results have agreed to the predictions based upon the above four models.  2001 Elsevier Science Ltd. All rights reserved. 1. Intrduction Electrical discharge machining (EDM), is a nontraditional machining process for metals removing based upon the fundamental fact that negligible tool force is generated during the machining

197 citations


Journal ArticleDOI
TL;DR: In this paper, a new comprehensive approach to select cutting parameters for damage-free drilling in carbon fiber reinforced epoxy composite material is presented, based on a combination of Taguchi's experimental analysis technique and a multi-objective optimization criterion.
Abstract: A new comprehensive approach to select cutting parameters for damage-free drilling in carbon fiber reinforced epoxy composite material is presented. The approach is based on a combination of Taguchi's experimental analysis technique and a multi-objective optimization criterion. The optimization objective includes the contributing effects of the drilling performance measures: delamination, damage width, surface roughness, and drilling thrust force. A hybrid process model based on a database of experimental results together with numerical methods for data interpolation are used to relate drilling parameters to the drilling performance measures. Case studies are presented to demonstrate the application of this method in the determination of optimum drilling conditions for damage-free drilling in BMS 8-256 composite laminate. A process map based on the results is presented as a tool for drilling process design and optimization for the investigated tool/material combination.

170 citations


Journal ArticleDOI
TL;DR: In this paper, two techniques are proposed for the on-line identification of tool wear based on the measurement of cutting forces and power signals using hidden Markov models (HMMs), commonly used in speech recognition.
Abstract: Monitoring of tool wear condition for drilling is a very important economical consideration in automated manufacturing. Two techniques are proposed in this paper for the on-line identification of tool wear based on the measurement of cutting forces and power signals. These techniques use hidden Markov models (HMMs), commonly used in speech recognition. In the first method, bargraph monitoring of the HMM probabilities is used to track the progress of tool wear during the drilling operation. In the second method, sensor signals that correspond to various types of wear status, e.g., sharp, workable and dull, are classified using a multiple modeling method. Experimental results demonstrate the effectiveness of the proposed methods. Although this work focuses on on-line tool wear condition monitoring for drilling operations, the HMM monitoring techniques introduced in this paper can be applied to other cutting processes.

168 citations


Journal ArticleDOI
TL;DR: In this article, it is argued that the angle of inclination of the contact plane is an important parameter for the achievement of high workspeeds and that workpiece melting provides an ultimate boundary for energy dissipation within the workpiece.
Abstract: Regimes of deep grinding range from creep grinding conducted at low workspeeds to High Efficiency Deep Grinding (HEDG) at fast workspeeds. At intermediate depths of cut, grinding is likely to be impossible due to high temperatures and damage to the workpiece and wheel. Analytical techniques for the determination of temperatures in deep grinding processes are discussed. An explanation is proposed for why it is possible to work efficiently at these two extremes of removal rate without experiencing the severe problems experienced in the intermediate range. Methods are required for determining the transition conditions so that process engineers can select process conditions for efficient material removal and high quality of manufactured products using high efficiency deep grinding. This paper provides a method for order of magnitude estimation of temperatures. It is proposed that the angle of inclination of the contact plane is an important parameter for the achievement of high workspeeds. It is argued that workpiece melting provides an ultimate boundary for energy dissipation within the workpiece.

Journal ArticleDOI
TL;DR: In this paper, two-dimensional orthogonal slot milling experiments in conjunction with an analytical-based computer code are used to determine flow stress data as a function of the high strains, strain rates and temperatures encountered in metal cutting.
Abstract: In the present study, two-dimensional orthogonal slot milling experiments in conjunction with an analytical-based computer code are used to determine flow stress data as a function of the high strains, strain rates and temperatures encountered in metal cutting. The workpiece materials selected for the present study are AISI P20 mold steel (DIN 1.2330, 35CrMo4) hardened to 30 HRC, AISI H13 tool steel (DIN 1.2344, X40CrMoV51) hardened to 46 HRC and Aluminum EN AW 2007 (DIN 1725 T1: AlCuMgPb, 3.1645) cold hardened to 100 HB. The methodology of flow stress determination for metal cutting, suggested in the present study, has advantages when compared with methods such as the Hopkinson's bar technique. This paper summarizes the first part of the study, conducted to estimate process variables in machining operations. The second part of the study, summarized in a different paper, addresses the application of flow stress data for predicting forces, stresses and temperatures in machining.

Journal ArticleDOI
TL;DR: In this paper, the effects of the insert runout errors and the variation of the feedrate on the surface roughness and the dimensional accuracy in a face-milling operation were analyzed.
Abstract: Optimization of feedrate is valuable in terms of providing high precision and efficient machining. The surface roughness is particularly sensitive to the feedrate and the runout errors of the inserts in a face-milling operation. This paper analyzes the effects of the insert runout errors and the variation of the feedrate on the surface roughness and the dimensional accuracy in a face-milling operation using a surface roughness model. The validity of the developed model was proved through cutting experiments, and the model was used to predict the machined surface roughness from the information of the insert runouts and the cutting parameters. From the estimated surface roughness value, the optimal feedrate that gave a maximum material removal rate under the given surface roughness constraint could be selected by a bisection method.

Journal ArticleDOI
TL;DR: In this paper, a numerical and experimental analysis of plasma enhanced machining of Inconel 718 is presented, where the results are compared with experimental results obtained with a radiation pyrometer.
Abstract: A numerical and experimental analysis of plasma enhanced machining (PEM) of Inconel 718 is presented in this paper. Surface temperatures due to plasma heating are systematically characterized through numerical modeling and experimental investigation using infrared radiation thermometry. A three-dimensional finite difference model is established to determine the temperature distribution in a cylindrical workpiece subjected to intense localized heating. The results are compared with experimental results obtained with a radiation pyrometer. A sensitivity analysis is presented to examine the effects of machining parameters on the temperature distribution. Benefits of PEM are also demonstrated through the reduction of cutting forces and improved surface roughness over a wide range of cutting conditions. In addition, improvement of productivity in machining Inconel with PEM is illustrated.

Journal ArticleDOI
TL;DR: In this article, a generalized mathematical model of inserted cutters for the purpose of predicting cutting forces, vibrations, dimensional surface finish and stability lobes in milling is presented, where the edge geometry is defined in the local coordinate system of each insert, and placed and oriented on the cutter body using the cutter's global coordinate system.
Abstract: Inserted cutters are widely used in roughing and finishing of parts. The insert geometry and distribution of inserts on the cutter body vary significantly in industry depending on the application. This paper presents a generalized mathematical model of inserted cutters for the purpose of predicting cutting forces, vibrations, dimensional surface finish and stability lobes in milling. In this paper, the edge geometry is defined in the local coordinate system of each insert, and placed and oriented on the cutter body using the cutter's global coordinate system. The cutting edge locations are defined mathematically, and used in predicting the chip thickness distribution along the cutting zone. Each insert may have a different geometry, such as rectangular, convex triangular or a mathematically definable edge. Each insert can be placed on the cutter body mathematically by providing the coordinates of the insert center with respect to the cutter body center. The inserts can be oriented by rotating them around the cutter body, thus each insert may be assigned to have different lead and axial rake angles. By solving the mechanics and dynamics of cutting at each edge point, and integrating them over the contact zone, it is shown that the milling process can be predicted for any inserted cutter. A sample of inserted cutter modeling and analysis examples are provided with experimental verifications.

Journal ArticleDOI
TL;DR: In this paper, position, velocity, and disturbance estimates are obtained using a Kalman filter and the feedback loop is closed using a pole placement controller with disturbance cancellation, in order to counteract the detrimental effects of friction, cutting forces, and drive parameter variations.
Abstract: A servo control system capable of delivering rapid and accurate feed motion is a necessity for high speed machine tools The control law must be designed to provide a high tracking bandwidth as well as adequate disturbance rejection and parameter variation robustness, in order minimize the following errors in each axis This also contributes to the minimization of the contour errors in the machined part This paper provides a systematic approach for designing such a control law Position, velocity, and disturbance estimates are obtained using a Kalman filter The feedback loop is closed using a pole placement controller with disturbance cancellation, in order to counteract the detrimental effects of friction, cutting forces, and drive parameter variations The overall tracking bandwidth is widened by compensating for the closed loop dynamics in a feedforward manner Also, the tracking errors due to friction transients at the corners and arc quadrants are reduced by precompensating for the expected friction forces The contribution of each component in the control scheme to the contouring accuracy has been experimentally verified, and the overall contouring performance has been demonstrated in high speed machining tests The experimental results were obtained using the smooth trajectory generation algorithm and identified axis and friction models which have been presented in Parts I and II respectively, of this paper

Journal ArticleDOI
TL;DR: In this paper, the analytical and experimental study on the high-speed face milling of 7075-T6 aluminum alloys with a single insert fly-cutter was conducted.
Abstract: This research is concerned with the analytical and experimental study on the high-speed face milling of 7075-T6 aluminum alloys with a single insert fly-cutter. The results are analyzed in terms of cutting forces, chip morphology, and surface integrity of the workpiece machined with carbide and diamond inserts. It is shown that a high cutting speed leads to a high chip flow angle, very low thrust forces and a high shear angle, while producing a thinner chip. Chip morphology studies indicate that shear localization can occur at higher feeds even for 7075-T6, which is known to produce continuous chips. The resultant compressive residual stresses are shown for the variation of cutting parameters and cutting tool material. The analysis of the high-speed cutting process mechanics is presented, based on the calculation results using extended oblique machining theory and finite element simulation.

Journal ArticleDOI
TL;DR: In this article, a combined system including a global stage (coarse stage) and a micro stage (fine stage) is designed, where a ball screw based servo motor is used as the global stage and a piezo actuator as the micro stage, in which some design parameters are analyzed.
Abstract: The ultra precision positioning technique has become one of the important parts in the development of precision machines. For positioning systems having a long stroke with ultra precision, a combined system including a global stage (coarse stage) and a micro stage (fine stage) is designed in this paper. A ball screw based servo motor is used as the global stage and a piezo actuator as the micro stage, in which some design parameters are analysed. To improve positional accuracy and remove the noise components of motion, the digital Chebyshev filter has been designed and implemented. The implemented digital filter has been found to improve accuracy by as much as three times. Positional accuracy has been readily achieved within 10 nm over the typical 200 mm stroke, and therefore this technique can be applied to develop high precision semiconductor equipment such as lithography steppers and probers.

Journal ArticleDOI
TL;DR: In this article, a polynomial network using a self-organizing adaptive modeling method is applied to construct the relationships between the feature of the surface image and the actual surface roughness under a variation of turning operations.
Abstract: The use of computer vision techniques to inspect surface roughness of a workpiece under a variation of turning operations has been reported in this paper. The surface image of the workpiece is first acquired using a digital camera and then the feature of the surface image is extracted. A polynomial network using a self-organizing adaptive modeling method is applied to constructing the relationships between the feature of the surface image and the actual surface roughness under a variation of turning operations. As a result, the surface roughness of the turned part can be predicted with reasonable accuracy if the image of the turned surface and turning conditions are given.

Journal ArticleDOI
TL;DR: In this article, a parametric analysis of single-point diamond turning (SPDT) is presented, where the properties of the surface roughness profiles are extracted and analyzed using the power spectrum analysis method.
Abstract: This paper describes a parametric analysis of nanosurface generation in single-point diamond turning (SPDT). The properties of the surface roughness profiles were extracted and analysed using the power spectrum analysis method. A series of face cutting experiments was undertaken on an aluminium alloy under various cutting conditions. The results indicate that the power spectrum of a surface roughness profile is basically composed of several periodical components that can be correlated to different process parameters and mechanisms of surface generation. Moreover, it is found that the tool feed, tool geometry, spindle error motions and relative vibration between the tool and the workpiece are not the only dominant components contributing to the surface generation in SPDT. Materials swelling and tool interference are other important factors. Based on these findings, relationships are proposed to explain the influence of tool interference on the variation of the spectral components and process parameters. The implications of these findings on the optimisation of the surface quality in SPDT are also discussed.

Journal ArticleDOI
TL;DR: In this paper, the authors analyzed the evolution of residual stresses, microstructure, microhardness and roughness in relation to the different parameters of milling, such as cutting speed and feed.
Abstract: The aim of this study is to analyse the evolution of residual stresses, microstructure, microhardness and roughness in relation to the different parameters of milling. For finishing milling, parameters are cutting speed and feed. The hole drilling strain gage technique was used to determine the residual stresses. These are measured from the surface to the bottom of the treated workpiece. Two different materials were used in this study: a carbon steel (CS) and a duplex stainless steel (DSS). The latter belongs to a high strength stainless steel family with high corrosion resistance properties. In this study, we have used the experimental system method to analyse the evolution of different surface characteristics in connection with cutting phenomena which are cutting forces, chip geometry and cutting temperature. We have noted that a high value of cutting speed used with a small value of feed improves the quality of the machined surface.

Journal ArticleDOI
TL;DR: In this article, a displacement method is proposed to shorten the measurement time and simplify the measurement by measuring the positioning errors along the 15 lines in the machine work zone, a total of 21 geometric error components can be determined.
Abstract: It is complicated and time-consuming to evaluate the performance of a machine tool. In this research, a displacement method is proposed to shorten the measurement time and to simplify the measurement. By measuring the positioning errors along the 15 lines in the machine work zone, a total of 21 geometric error components can be determined. Among the 15 lines, seven of them are mandated by the ANSI/ASME standard for the performance evaluation of CNC machining centers. Therefore, only eight additional positioning error measurements are necessary to evaluate the machine's performance. The results from the experimental tests show that the method is feasible and accurate. This method shortens the calibration time and is beneficial, particularly to the reconfigurable machining system, which needs frequent calibration.

Journal ArticleDOI
TL;DR: In this article, an artificial neural network (ANN) approach was proposed for the detection of workpiece "burn", the undesirable change in metallurgical properties of the material produced by overly aggressive or otherwise inappropriate grinding.
Abstract: An artificial neural network (ANN) approach is proposed for the detection of workpiece “burn”, the undesirable change in metallurgical properties of the material produced by overly aggressive or otherwise inappropriate grinding. The grinding acoustic emission (AE) signals for 52100 bearing steel were collected and digested to extract feature vectors that appear to be suitable for ANN processing. Two feature vectors are represented: one concerning band power, kurtosis and skew; and the other autoregressive (AR) coefficients. The result (burn or no-burn) of the signals was identified on the basis of hardness and profile tests after grinding. The trained neural network works remarkably well for burn detection. Other signal-processing approaches are also discussed, and among them the constant false-alarm rate (CFAR) power law and the mean-value deviance (MVD) prove useful. © 2000 Elsevier Science Ltd. All rights reserved.

Journal ArticleDOI
TL;DR: In this article, a semi-empirical model of surface finish on work for various materials has been established by employing dimensional analysis based upon pertinent process parameters in the electrical discharge machining process.
Abstract: A semi-empirical model of surface finish on work for various materials has been established by employing dimensional analysis based upon pertinent process parameters in the electrical discharge machining process. The parameters of the model, such as peak current, pulse duration, electric polarity, and properties of materials, have been initially screened by the design of experiment procedure. Then, they have been systematically analyzed and later verified by making use of the Taguchi method. A model based on dimensional analysis of the model parameters has been established for verification. In addition, the predictions based on the semi-empirical model with the best-fitting parameters by nonlinear optimization methods are in good agreement with the experimental verifications.

Journal ArticleDOI
TL;DR: In this paper, the uniqueness and the special requirements of the silicon wafer fine grinding process are introduced and some experimental results on the fine grinding of silicon wafers are presented and discussed.
Abstract: Silicon wafers are used for the production of most microchips. Various processes are needed to transfer a silicon crystal ingot into wafers. As one of such processes, surface grinding of silicon wafers has attracted attention among various investigators and a limited number of articles can be found in the literature. However, no published articles are available regarding fine grinding of silicon wafers. In this paper, the uniqueness and the special requirements of the silicon wafer fine grinding process are introduced first. Then some experimental results on the fine grinding of silicon wafers are presented and discussed. Tests on different grinding wheels demonstrate the importance of choosing the correct wheel and an illustration of the proper selection of process parameters is included. Also discussed are the effects of the nozzle position and the flow rate of the grinding coolant.

Journal ArticleDOI
TL;DR: In this article, the effect of roller-burnishing on surface roughness, surface microhardness and residual stress of 6061-T6 aluminum alloy was investigated using a deflection-etching technique.
Abstract: Roller-burnishing is used in place of other traditional methods to finish 6061-T6 aluminum alloy. How to select the burnishing parameters to improve surface integrity (reduce surface roughness, increase surface microhardness and produce compressive residual stress) is especially crucial. This paper presents an investigation of the effect of roller-burnishing upon surface roughness, surface microhardness and residual stress of 6061-T6 aluminum alloy. The residual stress distribution in the surface region that was burnished is determined using a deflection-etching technique. Mathematical models correlating three process parameters: burnishing speed, burnishing depth of penetration and number of passes, are established. A Group Method of Data Handling Technique, GMDH, is used. It is shown that low burnishing speeds and high depths of penetration produce much smoother surfaces, whereas a combination of high speed with high depth leads to rougher surfaces because of chatter. The optimum number of passes that produces a good surface finish was found to be 3 or 4. The maximum value of compressive residual stress decreases with an increase in burnishing speed. The maximum compressive residual stress increases with an increase in burnishing depth of penetration and/or number of passes.


Journal ArticleDOI
TL;DR: In this article, a control chart for drilling burr formation for stainless, AISI 304L, and low alloy steel was developed, and split point twist drills were used for the experiments of this work.
Abstract: Control charts for drilling burr formation for stainless, AISI 304L, and low alloy steel, AISI 4118, were developed. Split point twist drills are used for the experiments of this work. A Drilling Burr Control Chart, based on experimental data, is a tool for prediction and control of drilling burrs. Burr classification was carried out based on the geometric characteristics, burr formation mechanisms and sizes of the burrs. New parameters consisting of cutting condition variables and drill diameter were developed, and used to show unique distributions of the burr types. Burr types and the resultant burr size showed great dependence on the new parameters regardless of the drill diameters. Through the chart, burr type can be predicted with given cutting conditions. Also cutting conditions that are believed to create preferred burr types can be selected.

Journal ArticleDOI
TL;DR: In this article, the characterization and specification of tubular material properties under hydroforming conditions is the main concern of this paper, and analytical improvements and their comparison with experimental findings on measurement of material properties of tubes under hydraulic bulging conditions are explained.
Abstract: Increasing acceptance and use of hydroforming technology within the automotive industry demands a comprehensive understanding of related issues such as material characteristics, tribology, part and tooling design. Among these issues, characterization and specification of tubular material properties under hydroforming conditions is the main concern of this paper. Analytical improvements and their comparison with experimental findings on measurement of material properties of tubes under hydraulic bulging conditions are explained. With these improvements, ‘on-line’ and continuous measurement of flow stress for tubular materials become possible, and are proven to be in good agreement with previous ‘off-line’ measurements presented by the authors.

Journal ArticleDOI
TL;DR: A comprehensive and exhaustive review of various analytical material removal models for different advanced machining processes is presented in this article, which is intended to fulfil this need in the area of advanced machined material removal.
Abstract: Performance of any machining process is evaluated in terms of machining rate and surface finish produced. Higher machining rate and better surface finish are desirable for better performance of any machining process. Comprehensive qualitative and quantitative analysis of the material removal mechanism and subsequently the development of analytical model(s) of material removal (MR) are necessary for a better understanding and to achieve the optimum process performance. Analytical MR models are also necessary for simulation, optimization and planning (i.e. operation and process planning) of the process, prediction of process performance indicators, verification and improvements of experimental results, selection of appropriate models for specific type of work material and machining conditions, etc. Since the inception of different unconventional machining processes, various investigators have proposed different analytical models of material removal as functions of controllable process variables. A continual need for a comprehensive and exhaustive review of various analytical material removal models for different advanced machining processes is being felt. This paper is intended to fulfil this need in the area of advanced machining. Various analytical and some semi-empirical/empirical material removal models (approximately 40) for different mechanical type advanced machining processes have been comprehensively and exhaustively reviewed, and have been presented in a format suitable for quick reference.