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Showing papers on "Machining published in 1998"


Journal ArticleDOI
TL;DR: In this paper, a general formulation for the dynamic milling system is developed by modeling the cutter and workpiece as multi-degree-of-freedom structures, considering the varying dynamics in the axial direction.
Abstract: A new analytical method of chatter stability prediction in milling is presented. A general formulation for the dynamic milling system is developed by modeling the cutter and workpiece as multi-degree-of-freedom structures. The dynamic interaction between the milling cutter and workpiece is modeled considering the varying dynamics in the axial direction. The dynamic milling forces are governed by a system of periodic differential equations with delay whose stability analysis leads to an analytical relation for chatter stability limit in milling. The model can be used to determine the chatter free axial and radial depth of cuts without resorting to time domain simulations.

621 citations


Journal ArticleDOI
TL;DR: In this article, a general review of their material characteristics and properties together with their machinability assessment when using different cutting tools is presented, and the advantages and disadvantages of different tool materials with regard to the machining Inconel are highlighted.

536 citations


Journal ArticleDOI
TL;DR: In this paper, the fundamental principles of ultrasonic machining, the material removal mechanisms involved and the effect of operating parameters on material removal rate, tool wear rate and workpiece accuracy are reviewed, with particular emphasis on the machining of engineering ceramics.
Abstract: Ultrasonic machining is of particular interest for the cutting of non-conductive, brittle workpiece materials such as engineering ceramics. Unlike other non-traditional processes such as laser beam, and electrical discharge machining, etc., ultrasonic machining does not thermally damage the workpiece or appear to introduce significant levels of residual stress, which is important for the survival of brittle materials in service. The fundamental principles of ultrasonic machining, the material removal mechanisms involved and the effect of operating parameters on material removal rate, tool wear rate and workpiece accuracy are reviewed, with particular emphasis on the machining of engineering ceramics. The problems of producing complex 3-D shapes in ceramics are outlined.

416 citations


Journal ArticleDOI
TL;DR: In this paper, a general formulation for the milling chatter prediction developed in Part I of the paper is applied to common milling systems and three cases are considered: a workpiece with single-degree of freedom, a face milling cutter with two-degree-of-freedom, and peripheral milling of a cantilevered thin web.
Abstract: The general formulation for the milling chatter prediction developed in Part I of the paper is applied to common milling systems. Three cases are considered: a workpiece with single-degree-of-freedom, a face milling cutter with two-degree-of-freedom, and peripheral milling ofa cantilevered thin web. The general milling stability formulation is further simplified for the less complicated models. For each case, an analytical expression which explicitly relate the chatter limit to the milling conditions and tool-workpiece dynamics are derived. The analytical predictions are compared with numerical and time domain solutions proposed by previous research. It is shown that the proposed method can accurately predict the chatter limits in milling and thus eliminates the time consuming numerical solutions.

340 citations


Journal ArticleDOI
TL;DR: In this paper, a series of dry high-speed turning tests were performed to select the optimum tool material, tool geometry and cutting parameters for the turning of 20%SiC/Al metal-matrix composites.

328 citations


Journal ArticleDOI
TL;DR: In this article, a uniform wear method for 3D micro-EDM was proposed, which maintains the original electrode shape and converts the three dimensional electrode wear to a linear one.

298 citations


Journal ArticleDOI
TL;DR: In this article, a study of the near mirror-finish phenomenon in electrical discharge machining (EDM) when fine powder is introduced into the dielectric fluid as a suspension at the tool-workpiece or inter-electrode gap during machining is presented.

272 citations


Journal ArticleDOI
TL;DR: El-Gallab and Sklad as discussed by the authors investigated the effect of various cutting parameters on the surface quality and the extent of the sub-surface damage due to machining using polycrystalline diamond tools.

266 citations


Journal ArticleDOI
TL;DR: In this paper, a slip-line field is developed to model the ploughing components of the cutting force, based on other slip line fields developed for a rigid wedge sliding on a half space and for negative rake angle orthogonal cutting.
Abstract: Under normal machining conditions, the cutting forces are primarily due to the bulk shearing of the workpiece material in a narrow zone called the shear zone. However, under finishing conditions, when the uncut chip thickness is of the order of the cutting edge radiu a ploughing component of the forces becomes significant as compared to the shear forces. Predicting forces under these conditions requires an estimate of ploughing. A slip-line field is developed to model the ploughing components of the cutting force. The field is based on other slip-line fields developed for a rigid wedge sliding on a half-space and for negative rake angle orthogonal cutting. It incorporates the observed phenomena of a small stable build-up of material adhered to the edge and a raised prow of material formed ahead qf the edge, The model shows how ploughing forces are related to cutter edge radius - a larger edge causing larger ploughing forces, A series of experiments were run on 6061-T6 aluminum using tools with different edge radii-including some exaggerated in size-and different levels of uncut chip thickness. Resulting force measurements match well to predictions using the proposed slip-line field, The results show great promise for understanding and quantifying the effects of edge radius and worn tool on cutting forces.

242 citations


Journal ArticleDOI
04 Aug 1998-Wear
TL;DR: In this paper, the effect of tool geometry and depth of cut on the deformation of a single crystal diamond tool was investigated and the results were in reasonably good agreement with the experimental and simulation results reported in the literature, and a material removal mechanism was proposed that would cover the range from conventional machining to grinding, to ultraprecision machining, and finally to the indentation-sliding as a cognate transition for material removal operation.

217 citations


Journal ArticleDOI
TL;DR: In this paper, the state of the art in hard coatings for carbide cutting tools including discussion of coating characteristics and applications is presented, as well as a detailed discussion of their application.
Abstract: The majority of carbide cutting tools in use today employ hard coatings because coatings offer proven benefits in terms of tool life and machining performance. Continuing development of the chemical vapor deposition (CVD) coating process, the most widely used technique, has produced complex multilayer coatings tailored for specific applications and workpiece materials. These coatings include alumina layers of different crystal structures, and TiCN layers applied by high- or moderate-temperature (MT-CVD) processes. Over the last decade, coatings applied by physical vapor deposition (PVD) have gained acceptance in applications requiring sharp edges or those featuring interrupted cuts. Originally limited to TiN coatings, the PVD offering now includes TiCN and TiA1N coatings which provide better high-speed performance and increased abrasive wear resistance. In the area of superhard coatings, improvements in deposition processes and coating adhesion have resulted in diamond-coated carbide tools that have begun to play an important role in machining non-ferrous and non-metallic materials. This paper presents the state of the art in hard coatings for carbide cutting tools including discussion of coating characteristics and applications.

Journal ArticleDOI
TL;DR: In this article, the authors presented a model of a helical ball end mill attached to the spindle by orthogonal structural modes in the feed and normal directions at the tool tip.
Abstract: Mechanics and dynamics of cutting with helical ball end mills are presented. The helical ball end mill attached to the spindle is modelled by orthogonal structural modes in the feed and normal directions at the tool tip. For a given cutter geometry, the cutting coefficients are transformed from an orthogonal cutting data base using an oblique cutting model. The three dimensional swept surface by the cutter is digitized using the true trochoidal kinematics of ball end milling process in time domain. The dynamically regenerated chip thickness, which consists of rigid body motion of the tooth and structural displacements, is evaluated at discrete time intervals by comparing the present and previous tooth marks left on the finish surface. The process is simulated in time domain by considering the instantaneous regenerative chip load. local cutting force coefficients, structural transfer functions and the geometry of ball end milling process. The proposed model predicts cutting forces, surface finish and chatter stability lobes, and is verified experimentally under both static and dynamic cutting conditions.

Journal ArticleDOI
TL;DR: The techniques presented in this paper can be used to improve 5-axis machined surface quality and to automate the non-isoparametric cutter path generation for CAD/CAM systems.
Abstract: Presented in this paper is a new approach to 5-axis NC tool path generation for sculptured surface machining. Techniques of feasible machining strip evaluation are used for non-isoparametric 5-axis tool path generation. A searching algorithm is proposed to find the parameter increments of adjacent cutter locations along orthogonal path intervals for optimal non-isoparametric path generation. Compared to the use of the smallest path interval by the traditional constant parametric path planning, the proposed methodology can generate efficient tool paths for sculptured surface machining by reducing the redundant overlapping between adjacent tool paths. The proposed methodology includes three steps: (1) evaluating feasible machining strip, (2) solving parameter increments (Δu, Δv) along orthogonal path intervals, and (3) searching for adjacent non-isoparametric cutter locations. The techniques presented in this paper can be used to improve 5-axis machined surface quality and to automate the non-isoparametric cutter path generation for CAD/CAM systems.

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate the ability to directly fabricate complex shapes using a 5-axis Directed Light Fabrication (DLF) machine and demonstrate that near-net shape tolerance levels are attainable within a 0.1 mm envelope.

Book
01 Jan 1998
TL;DR: In this article, nonlinear and chaotic dynamics in manufacturing processes dynamic modelling and control of machine processes chatter dynamics in sheet rolling processes modelling, analysis and characterization of machining dynamics applications of perturbation methods to tool chatter dynamics nonlinear dynamics and surface integrity in machining ceramics.
Abstract: Nonlinear dynamics in manufacturing processes: nonlinear and chaotic dynamics in manufacturing processes dynamic modelling and control of machine processes chatter dynamics in sheet rolling processes modelling, analysis and characterization of machining dynamics applications of perturbation methods to tool chatter dynamics nonlinear dynamics and surface integrity in machining ceramics. New methods in nonlinear dynamics and control: nonlinear dynamics with impacts and friction controlling chaos in mechanical systems experimental control of high dimensional chaos (Part contents).

Journal ArticleDOI
TL;DR: In this article, a simple technique of drilling Kevlar composites by using slightly modified high-speed steel (HSS) drill bits at commonly available rotational speeds is described.

Journal ArticleDOI
TL;DR: In this paper, a tool force model that could form the basis of this new control technique has been developed by measuring the shear angle from micrographs of chip cross sections equations for the forces due to chip formation and the friction between the chip and the tool.
Abstract: The accuracy of precision machining operations could be improved through tool force feedback. Tool force is ideally suited for use in a control algorithm because it contains information on the instantaneous depth of cut, feed rate and condition of the tool. A tool force model that could form the basis of this new control technique has been developed. By measuring the shear angle from micrographs of chip cross sections equations for the forces due to chip formation and the friction between the chip and the tool have been written. Furthermore, the effects of elastic deformation of the workpiece (spring back) on chip formation and the measured forces, which can be significant in precision machining, have been included in the model. Machining experiments were conducted with a 0 deg rake diamond tool and four metals that are commonly diamond turned. For machining with newly lapped as well as worn tools, the calculated forces were in excellent agreement with the measured values for the array of workpiece materials.

Journal ArticleDOI
Ichiro Inasaki1
TL;DR: By applying these methods, it has become possible to take the AE signal from the rotating tools and in terms of AE signal processing for identifying the machining processes, application of the artificial neural network will be introduced.

Journal ArticleDOI
TL;DR: In this paper, an analysis of the chatter behavior for a slender cutting tool in turning in the presence of wear flat on the tool flank is presented in the context of cutting force and contact force.
Abstract: An analysis of the chatter behavior for a slender cutting tool in turning in the presence of wear flat on the tool flank is presented in this research. The mechanism of a self-excited vibration development process with tool wear effect is studied. The components contributing to the forcing function in the turning vibration dynamics are analyzed in the context of cutting force and contact force. A comparison of the chatter stability for a fresh cutting tool and a worn cutting tool is provided. Stability plots are presented to relate width of cut to cutting velocity in the determination of chatter stability. Machining experiments at various conditions were conducted to identify the characteristic parameters involved in the vibration system and to identify the analytical stability limits. The theoretical result of chatter stability agrees qualitatively with the experimental result concerning the development of chatter stability model with tool wear effect.

Journal ArticleDOI
TL;DR: In this article, the success of the turning process depends on optimizing the machining parameters such as feed rate, depth of cut, tool rake angles, the cutting lubricants and the crystallographic orientation of the crystal being cut.

Patent
17 Apr 1998
TL;DR: In this article, a combination of multiphoton and collisional ionization creates a critical density plasma in a time scale much shorter than electron kinetic energy is transferred to the lattice.
Abstract: The invention consists of a method for machining (cutting, drilling, sculpting) of explosives (e.g., TNT, TATB, PETN, RDX, etc.). By using pulses of a duration in the range of 5 femtoseconds to 50 picoseconds, extremely precise and rapid machining can be achieved with essentially no heat or shock affected zone. In this method, material is removed by a nonthermal mechanism. A combination of multiphoton and collisional ionization creates a critical density plasma in a time scale much shorter than electron kinetic energy is transferred to the lattice. The resulting plasma is far from thermal equilibrium. The material is in essence converted from its initial solid-state directly into a fully ionized plasma on a time scale too short for thermal equilibrium to be established with the lattice. As a result, there is negligible heat conduction beyond the region removed resulting in negligible thermal stress or shock to the material beyond a few microns from the laser machined surface. Hydrodynamic expansion of the plasma eliminates the need for any ancillary techniques to remove material and produces extremely high quality machined surfaces. There is no detonation or deflagration of the explosive in the process and the material which is removed is rendered inert.

Journal ArticleDOI
TL;DR: In this article, an approach to modeling the ductile-mode removal in rotary ultrasonic machining is proposed, and the results of the pilot experiments to verify the model are discussed.
Abstract: In rotary ultrasonic machining of ceramic materials there exist two modes of material removal: brittle fracture mode and ductile mode. Two models were developed based on the assumption that the brittle fracture is the dominating mode of material removal, and were published previously. This paper presents the follow-up work on modeling of the ductile-mode material removal in rotary ultrasonic machining. After a brief review of the ductile phenomena in ceramic machining, an approach to modeling the ductile-mode removal in rotary ultrasonic machining is proposed. Then, magnesia stabilized zirconia is used to demonstrate the model's capability of predicting the material removal rate from the process parameters and the material property of the workpiece. Finally, the results of the pilot experiments to verify the model are discussed.

Journal ArticleDOI
TL;DR: In this paper, a machining process with the superimposing of ultrasonics is considered and the accumulated experimental results are explained theoretically in the framework of rheological models.

Journal ArticleDOI
Ibrahim N. Tansel1, O. Rodriguez1, M Trujillo1, E. Paz1, W. Li1 
TL;DR: In this paper, the failure mechanisms of micro-end-mills were studied during the machining of aluminum, graphite electrodes and mild steel workpieces, and the cutting force variation was monitored, i.e., the relationship between the utilization-related changes at the tool structure (wear), and the outcomes (increasing cutting force which means raising stress on the tiny shaft).
Abstract: Unpredictable tool life and premature tool failure are major problems in micro-machining. In this study, the failure mechanisms of micro-end-mills were studied during the machining of aluminum, graphite electrodes and mild steel workpieces. Hundreds of machining operations were performed, and the pictures of cutting edges were taken with a scanning electron microscope to identify fatigue and extensive stress-related failure mechanisms. Also, the cutting force variation was monitored, i.e. the relationship between the utilization-related changes at the tool structure (wear), and the outcomes (increasing cutting force which means raising stress on the tiny shaft). Inspection of the cutting force variation patterns of large numbers of micro-end-mills indicated that tool failure occurs with chip clogging, fatigue and wear-related excessive stress depending on the characteristics of the workpiece. Two tool breakage prediction methods were developed by considering the variation of the static part of the feed direction cutting force. These methods used segmental averages and wavelet transformation coefficients. The accuracy of the proposed approaches were tested with experimental data and the agreement between the predictions and actual observations are reported.

Journal ArticleDOI
TL;DR: In this paper, a rotational tool with controlled feed has been used to improve the performance of electrochemical spark machining (ECSM) for nonconducting materials, such as ceramics and composites.
Abstract: Machining of electrically non-conducting materials, i.e. ceramics, composites, etc., is still a major problem. Electrochemical spark machining (ECSM) is found to be a potential process for machining these materials. However, ECSM has its own inherent problems too. So far, only non-rotational tools with gravity feed have been used 'by previous researchers, but the performance of such tools has been reported to be poor. In the present work, electrochemical spark drilling (ECSD) experiments have been conducted using various tool kinematics with a view to enhancing the process capabilities. Use of a rotational tool with controlled feed has been found to improve the process performance. Significant improvement in the “limiting value” of the machined depth during ECSD has been observed while using a tool with orbital motion. Geometrical parameters and surface integrity of the machined specimens have also been studied and presented.

Journal ArticleDOI
TL;DR: In this article, a simulation system for machining with ball-end milling cutters is presented, where the geometry of the workpiece, the cutter, and the cutter/workpiece engagement is modeled using a geometric simulation system.
Abstract: A simulation system is developed in this paper, which deals with the geometry and mechanics of machining with ball-end milling cutters. The geometry of the workpiece, the cutter, and the cutter/workpiece engagement is modeled using a geometric simulation system. This module uses a commercial solid modeler (ACIS) as a geometric engine and automatically extracts the critical geometric information required for the physical simulation system. To calculate the instantaneous cutting forces, a new mechanistic force model is developed. This force model takes into account the variations of the cutting coefficients along the cutting edge, and considers the variations of the rake angle and the chip flow direction on the rake face. The calibration of the developed model is performed for half-immersion ball-end milling operation. The applicability of the developed system is verified experimentally for various up-hill angles. It is shown that as the up-hill angle increases, the ball-nose tip engagement decreases which in turn significantly affects the magnitude of the resultant forces. Also, lower cutting forces and powers are experienced if cutting with the vicinity of the tool tip is avoided.

Journal ArticleDOI
TL;DR: In this article, the authors present the physical and mathematical models on the basis of which of the simulation process module in the computer-aided engineering system for ECM (CAE-ECM) has been developed.

Journal ArticleDOI
TL;DR: In this paper, the authors present the research work under the authors and their team in this area, which has been applied to more than 10 different kinds of machines including: turning centers and machining centers; small, medium and large machines; new products and retrofitted machines.

Patent
04 May 1998
TL;DR: A hybrid tool is a hybrid tool which serves both as a form on which constituent materials are applied for bonding or curing into a part in a desired configuration, and for holding the bonded or cured materials in the originally applied position during subsequent machining of a peripheral edge of the part by a CNC machine tool.
Abstract: A method of manufacturing a hybrid tool which serves both as a form on which constituent materials are applied for bonding or curing into a part in a desired configuration, and for holding the bonded or cured materials in the originally applied position during subsequent machining of a peripheral edge of the part by a CNC machine tool.

Journal ArticleDOI
TL;DR: Inconel 718 is a nickel-base alloy that is difficult to machine, a high cutting force being generated in the machining of this advanced material is reported in this article.