Showing papers on "Machining published in 1997"
TL;DR: In this article, the main problems associated with the machining of titanium as well as tool wear and the mechanisms responsible for tool failure are discussed. But no equivalent development has been made for cutting titanium alloys due primarily to their peculiar characteristics.
1,417 citations
TL;DR: In this paper, a concept of delamination factor F d (i.e., the ratio of the maximum diameter D max in the damage zone to the hole diameter D ) is proposed to analyze and compare easily the delamination degree in the drilling of carbon fiber-reinforced plastic (CFRP) composite laminates.
Abstract: In this paper, a concept of delamination factor F d (i.e. the ratio of the maximum diameter D max in the damage zone to the hole diameter D ) is proposed to analyze and compare easily the delamination degree in the drilling of carbon fiber-reinforced plastic (CFRP) composite laminates. Experiments were performed to investigate the variations of cutting forces with or without onset of delamination during the drilling operations. The effects of tool geometry and drilling parameters on cutting force variations in CFRP composite materials drilling were also experimentally examined. The experimental results show that the delamination-free drilling processes may be obtained by the proper selections of tool geometry and drilling parameters. The effects of drilling parameters and tool wear on delamination factor are also presented and discussed. Cutting temperature has long been recognized as an important factor influencing the tool wear rate and tool life. An experimental investigation of flank surface temperatures is also presented in this paper. Experimental results indicated that the flank surface temperatures increase with increasing cutting speed but decreasing feed rate. Optimal cutting conditions are proposed to avoid damage from burning during the drilling processes.
634 citations
TL;DR: In this article, the authors investigated the thermal properties of high-speed machining of Inconel 718 and Ti 6Al 6V 2Sn alloys from a thermal point of view.
500 citations
TL;DR: In this paper, the effect of cutting conditions on the machinability of Inconel 718 was discussed and two types of coated cemented carbide inserts, grades EH20Z-UP and AC25, were tested at a constant depth of cut.
317 citations
TL;DR: In this article, the state-of-the-art machining technologies for three-dimensional microproducts are summarized by focusing on the methods using tools, and promising methods for machining convex and concave shapes are introduced and discussed with respect to their state of the art.
290 citations
TL;DR: In this paper, the effects of hole machining defects on strength and fatigue life of carbon/epoxy laminates subjected to static and fatigue loading are presented, and the KTH method, a new method which gives defect-free holes, was used to machine holes in the specimens.
Abstract: The effects of hole machining defects on strength and fatigue life of carbon/epoxy laminates subjected to static and fatigue loading are presented. Dry specimens were subjected to pin loading and uniaxial compressive loading at room temperature. The KTH method, a new method which gives defect-free holes, was used to machine holes in the specimens. For comparison, holes were also machined using two traditional drilling techniques causing varying extents of damage. X-ray techniques were used to detect the hole machining defects. The permanent deflection of compressively loaded specimens was monitored during cyclic loading. Hole machining defects significantly reduced the static and fatigue strengths of pin-loaded laminates; the effects on the strengths of compressively loaded laminates were less pronounced.
284 citations
TL;DR: In this paper, the authors focus on fine abrasive processes with emphasis on material removal in brittle workmaterials, and make an attempt to rationalize various models by linking conventional machining, grinding, ultraprecision machining and indentation sliding.
282 citations
TL;DR: In this article, a machine tool assembly is easily reconfigurable to perform single or multiple machining processes on a workpiece so that this machine has exactly the functionality required to perform a given set of machining tasks.
Abstract: In accordance with the teachings of the present invention, a machine tool assembly is easily reconfigurable to perform single or multiple machining processes on a workpiece so that this machine has exactly the functionality required to perform a given set of machining tasks. The invention allows rapid changes in the machine structure and rapid conversion of the machine by relocating its basic building blocks. The assembly secures a raw workpiece to a table and includes support units that carry at least one single-axis spindle unit. The spindle units are easily attached to one of the support units and are easily movable thereon to perform machining processes from various positions and orientations relative the workpiece. A cutting tool, or other machining tool, is secured to each spindle, which is computer controlled to rotate the tool and stroke it linearly along its axis of rotation. The support units are reconfigurable and can be easily relocated to different positions and orientations about the workpiece.
268 citations
TL;DR: Since the introduction of glass fiber-reinforced polymer composites in the early 1940s, composite materials development was driven by the needs of space, defense, and aircraft industries.
Abstract: Since the introduction of glass fiber-reinforced polymer composites in the early 1940s, composite materials development was driven by the needs of space, defense, and aircraft industries w...
210 citations
TL;DR: In this paper, the authors examined the feasibility of an intelligent sensor fusion technique to estimate on-line surface finish (Ra) and dimensional deviations (DD) during machining and presented a systematic method for sensor selection and fusion using neural networks.
Abstract: This paper examines the feasibility for an intelligent sensor fusion technique to estimate on-line surface finish (Ra) and dimensional deviations (DD) during machining. It first presents a systematic method for sensor selection and fusion using neural networks. Specifically, the turning of free-machining and low carbon steel is considered. The relationships of the readily sensed variables in machining to Ra and DD, and their sensitivity to process conditions are established. Based on this experimental data and using statistical tools, the sensor selection and fusion method assists the experimenter in determining the average effect of each candidate sensor on the performance of the measuring system. In the case studied, it appeared that the cutting feed, depth of cut and two components of the cutting force (the feed and radial force components) provided the best combination to build a fusion model for on-line estimation of Ra and DD in turning. Surface finish was assessed with an error varying from 2 to 25% under different process conditions, while errors ranging between 2 and 20 μm were observed for the prediction of dimensional deviations.
195 citations
TL;DR: In this article, the results of preliminary tests using very low quantities (200 −300 ml h −1 ) of lubricant when machining steel were compared to traditional flood cooling as a benchmark with 5.2I min −1.
TL;DR: In this article, a suitable selection of machining parameters for wire electrical discharge machining (WEDM) process relies heavily on the operators' technologies and experience because of their numerous and diverse range.
TL;DR: The techniques presented in this paper can be used to eliminate errors of tool paths as they are generated and automate the planning and programming of cutter path generation for 5-axis machining.
Abstract: This paper presents a methodology and algorithms of admissible tool orientation control for gouging avoidance in 5-axis machining. A method is proposed to find the admissible tool orientation by considering both local and global surface shapes. A filleted endmill is used in this study for 5-axis machining. Based on the evaluation of local surface shape, a geometry analysis method is developed to first find a feasible tool orientation for gouging avoidance along two orthogonal cutting places. Adjacent geometry is then taken into consideration for detecting possible rear gouging. A localization algorithm is developed for filleted endmills to identify potential rear gouging area. Both the circular approximation, and the detailed gouging checking methods are proposed for rear gouging correction. The techniques presented in this paper can be used to eliminate errors of tool paths as they are generated. Unlike the traditional graphical verification and user-interactive correction of tool path generation, the proposed methodology can be used to automate the planning and programming of cutter path generation for 5-axis machining.
TL;DR: In this article, a dual fracture process was used to simulate chip formation incorporating both the maximum stress and Tsai-Hill failure criteria, and the principal cutting force predictions agreed very well with those obtained from experiments.
TL;DR: In this paper, the authors present a review of HSM machinability work over the last decade and include tool life, workpiece surface finish/dimensional accuracy and cost data.
TL;DR: It is suggested, with some supportive results, that the Z-map model might be a suitable representation scheme for implementing the C-space method, which provides a number of distinctive features suitable for high speed machining of dies and moulds.
Abstract: Presented in the paper is a new approach to 3-axis NC tool-path generation for sculptured surface machining. In the proposed C-space approach, the geometric data describing the design-surface and stock-surface are transformed into C-space elements, and then, all the tool-path generation decisions are made in the configuration space (C-space). The C-space approach provides a number of distinctive features suitable for high speed machining of dies and moulds, including: (1) gouge-free and collision-free tool-paths; (2) balanced cutting-loads; (3) smooth cutter movements; and (4) verification mechanisms. It is suggested, with some supportive results, that the Z-map model might be a suitable representation scheme for implementing the C-space method. Also discussed are other implementation as well as future research directions.
Patent•
06 Nov 1997
TL;DR: In this article, a set of rational functions with respect to parameters u and v is defined and the solution of the solution is calculated by an analytically focusing method with the initial value set between the extremal value and the point of inflection.
Abstract: Data about a plurality of curved surfaces which are
expressed in various forms are inputted (S1), and based on
the inputted data, the curved surfaces are defined (S2, S3)
by a set of rational functions with respect to parameters u
and v. Then, calculation for intersections which are
necessary for machining is carried out, and paths of a
cutting tool are calculated. In figuring out the solution of
the set of rational functions, first, the extremal value and
the point of inflection are calculated, and the solution is
calculated by an analytically focusing method with the
initial value set between the extremal value and the point
of inflection. When a plurality of curved surfaces are
expressed in the same form, the curved surfaces are unified
into a single surface.
01 Jan 1997-Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology
TL;DR: In this paper, a feed-forward back-propagation neural network based on a central composite rotatable experimental design is developed to model the WEDM process, and an autoregressive AR(3) model is used to describe its stochastic component.
Abstract: Wire electrical discharge machining (WEDM) technology has been widely used in conductive material machining. The WEDM process, which is a combination of electrodynamic, electromagnetic, thermaldynamic, and hydrodynamic actions, exhibits a complex and stochastic nature. Its performance, in terms of surface finish and machining productivity, is affected by many factors. This paper presents an attempt at optimization of the process parametric combinations by modeling the process using artificial neural networks (ANN) and characterizes the WEDMed surface through time series techniques. A feed-forward back-propagation neural network based on a central composite rotatable experimental design is developed to model the machining process. Optimal parametric combinations are selected for the process. The periodic component of the surface texture is identified, and an autoregressive AR(3) model is used to describe its stochastic component.
TL;DR: In this paper, a response surface model based on a central composite rotatable experimental design and a 4-16-3 size back-propagation neural network have been developed.
TL;DR: An overview of the basic research and development activities in the area of abrasive waterjet machining in the 1990s in the United States can be found in this paper, where the authors give an overview of some of the most important advances in this area.
Abstract: Thermodynamic analysis of material removal mechanisms indicates that an ideal tool for shaping of materials is a high energy beam, having infinitely small cross-section, precisely controlled depth, and direction of penetration, and does not cause any detrimental effects on the generated surface. The production of the beam should be relatively inexpensive and environmentally sound while the material removal rate should be reasonably high for the process to be viable. A narrow stream of high energy water mixed with abrasive particles comes close to meeting these requirements because abrasive waterjet machining has become one of the leading manufacturing technologies in a relatively short period of time. This paper gives an overview of the basic research and development activities in the area of abrasive waterjet machining in the 1990s in the United States.
TL;DR: In this paper, the effects of current setting and pulse-on time on the fatigue lives of AISI D6 tool steel specimens produced using three-dimensional cavity machining are investigated.
TL;DR: In this paper, the authors present an optimization system which determines the optimum machining parameters for milling operations, which are intended for use by NC machines, however, they can also be used by conventional machines.
Abstract: Owing to the significant role that machining parameters play in performing successful and efficient machining operations, determination of the best or optimum machining parameters is still the subject of many studies. The need to use optimum machining parameters to improve machining efficiency is of greater importance when NC machines with high capital cost are employed. This paper describes development and utilization of an optimization system which determines optimum machining parameters for milling operations. These parameters are intended for use by NC machines, however, they can also be used by conventional machines. The paper discusses both single-tool and multi-tool milling operations where emphasis has been placed on the latter. An example has been presented at the end of the paper to give a clear picture from the application of the system and its efficiency.
Journal Article•
TL;DR: Machining tolerance, an intrinsic characteristic that exists between machined implant components, identifies the amount of horizontal shift possible between paired components.
Abstract: Machining tolerance, an intrinsic characteristic that exists between machined implant components, identifies the amount of horizontal shift possible between paired components. Machining tolerances between implant components (abutment, gold, cylinder, impression coping, and brass abutment replicas) were measured with a coordinate measuring machine. The measured tolerances ranged from 22 to 100 microns. Machining tolerances between implant components should be included in future studies of accuracy, because it is an inherent characteristic of the component itself.
TL;DR: In this article, the authors give an overview of recent developments and research trends in laser assisted machining. But there are still unresolved problems regarding the limitations of the techniques, optimum machining conditions, etc.
Abstract: Since laser technology has considerable synergy with machining technologies, Laser Machining (LM) and Laser Assisted Machining (LAM) are relevant research topics. This paper attempts to give an overview of recent developments and research trends. Although scientific work on this area has contributed to the understanding of the process, there are still unresolved problems regarding the limitations of the techniques, optimum machining conditions, etc. The outcome of experimental investigations on LAM shows potential applications for this process but there are several issues to be resolved.
TL;DR: In this article, a simplified model is developed to predict the characteristics of the material removal rate for varying input parameters with the objective of finding the possibility of enhancing the capability of the process.
TL;DR: In this article, an attemopt is made to extract maximum information from acoustic emission (AE) signals acquired during machining, and a statistical method, the time series modelling technique, is used to extract parameters called features representing the state of the cutting process.
TL;DR: A postprocessor capable of converting cutter location (CL) data to machine control data for three typical five-axis machine tools to establish an interface between computer-aided manufacturing (CAM) systems and numerically controlled (NC) machines is presented in this article.
Abstract: This paper presents a postprocessor capable of converting cutter location (CL) data to machine control data for three typical five-axis machine tools to establish an interface between computer-aided manufacturing (CAM) systems and numerically controlled (NC) machines. The analytical equations for NC data are obtained using the homogeneous coordinate transformation matrix and inverse kinematics. In addition, the developed postprocessor method is implemented through a trial-cut on a five-axis machine and verified on the coordinate measurement machine. Experimental results confirmed the effectiveness of the proposed postprocessor method which can be used to integrate the various five-axis machine tools employed in manufacturing systems.
TL;DR: In this paper, the extent of the flank wear land has been determined using both textural and gradient operators; a texture operator has been implemented in the final system, which consists of a fibre-optic light source to illuminate the tool and a CCD camera (used in conjunction with a high resolution video zoom microscope) to capture the reflected pattern.
TL;DR: An overview of the state of the art in high-speed machining and a view of the emerging research areas can be found in this paper, where the focus of research has shifted to maximizing the cutting performance of the machine tool.
Abstract: The focus of the majority of high-speed machining research has been directed toward improving metal removal rates. Tool materials capable of withstanding high cutting speeds have become available (silicon nitride for cast iron, solid carbide for aluminum, and superabrasives for hardened steels), and the focus of research has shifted to maximizing the cutting performance of the machine tool. Measurement of cutting performance, chatter avoidance, structural design, tool retention, and axis control have become important research topics. The purpose of this paper is to provide an overview of the state of the art in high-speed machining and to provide our view of the emerging research areas.
TL;DR: In this article, a study of the development of mathematical models for tool life in end milling steel (190 BHN) using high-speed steel slot drills under dry conditions is presented.