Showing papers on "Machining published in 1992"
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TL;DR: The implementation of fundamental knowledge of high-speed machining into the manufacture of industrial products took a relatively long time as discussed by the authors, not only due to a cautious attitude of the industry, but also to the production facilities existing at the time when the first findings became available from research not meeting the requirements of high speed machining.
419 citations
254 citations
TL;DR: In this paper, the machinability of a specific particulate aluminium matrix composite (AISi7Mg) alloy reinforced with 14 Vol% Sic was investigated and the main objects of the investigations were tool wear, cutting forces and surface roughness.
244 citations
TL;DR: In this article, the critical depth of cut for ductile cutting is increased and the surface profile of diamond cutting edge is better transferred to the cut groove as compared to the conventional cutting.
207 citations
TL;DR: In this article, a model for the optimization of machining conditions in a multi-pass turning operation is presented, where both rough cutting and finishing cutting are considered in the model and dual optimization of cost functions for each subproblem is pursued.
Abstract: This paper presents a model for the optimization of machining conditions in a multi-pass turning operation. Both rough cutting and finishing cutting are considered in the model and dual optimization of cost functions for each subproblem is pursued. The preventive tool replacement strategy used in practice is incorporated. Machining idle time is also regarded as a variable. After practical constraints are established, optimization is carried out using the dynamic programming method. An example illustrates the formulation of the problem and the optimization procedure
198 citations
TL;DR: In this article, the significance of the minimum thickness of cut (MTC) which is defined as the minimum undeformed thickness of chip removed from a work surface at a cutting edge under perfect performance of a metal cutting system was discussed.
Abstract: The authors discuss the significance of the minimum thickness of cut (MTC) which is defined as the minimum undeformed thickness of chip removed from a work surface at a cutting edge under perfect performance of a metal cutting system. Following a brief look at the relation between MTC and the extreme machining accuracy attainable for a specific cutting condition, it is shown that a very fine chip with an undeformed thickness of the order of a nanometer can be obtained from experimental face turning of electroplated copper by a well-defined diamond tool. To understand the nanometric metal cutting process, a computer simulation using an atomistic model is proposed.
172 citations
Patent•
03 Apr 1992
TL;DR: In this paper, the authors proposed to make the whole capacity of a power source in a small size and reduce useless power loss, by providing inverters divided into one for high voltages and one for low voltage high currents, controlling the divided inverters synchronously, and applying the outputs to a machining gap in series.
Abstract: PURPOSE:To make the whole capacity of a power source in a small size and reduce useless power loss, by providing inverters divided into one for high voltages and one for low voltage high currents, controlling the divided inverters synchronously, and applying the outputs to a machining gap in series. CONSTITUTION:AC-DC-HF-P inverters, one 51 for high voltages and one 52 for low voltage high currents, are provided and controlled synchronously, and the outputs are connected in series and applied to a machining gap 6 to start the discharge in the gap 6. After the start of discharge, sufficient machining currents are supplied from the inverter 52 for low voltage high currents. By dividing inverters into one 51 for high voltages and one 52 for low voltage high currents, the whole capacity of a power source can be made in a small size, and useless power loss can be reduced.
157 citations
TL;DR: In this article, the tool wear of metal matrix composites caused by the hardness of the ceramic fibres and particles is extremly high and the use of high speed steel tools (HSS) is not possible.
156 citations
01 May 1992-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, a pin-on-disc machine was used to determine the wear rate of squeeze cast Al alloy (BSS: LM11) matrix composites under varying applied pressure at a sliding spped of 2.68 m s−1 against a rotating EN25 steel disc.
Abstract: Squeeze cast Al alloy (BSS: LM11) matrix composites, each containing 10 vol.% of SiC particles or fibres, have been investigated for their resistance to dry wear under varying applied pressures (1–3 MPa) at a sliding spped of 2.68 m s−1 against a rotating EN25 steel disc. Seizure pressure of the composites as well as the base alloy was determined using a pin-on-disc machine. The alloy containing SiC particles showed less wear rate than the one having SiC fibre dispersion. The base alloy showed maximum rate of wear. Dispersoid-matrix interfacial bonding and shape of the dispersoid were found to play an important role in governing the wear rate of the composites. Scanning electron microscopy examinations indicated relatively finer grooves on the wear surfaces prior to seizure, while seizure led to severely damaged surfaces. Similarly, wear debris generated during wear was thin and flaky prior to seizure, while bulky debris particles were observed during seizure. A few iron machining chips were also found in all the cases. The results obtained have been explained on the basis of wear-induced microstructural changes and deformation, leading to work hardening in the subsurface regions and wear debris.
149 citations
TL;DR: In this paper, a study of reinforced thermoset and thermoplastics for characterizing their responses to machining is presented, and the results are useful in establishing a mathematical model to predict torque and thrust in drilling of composite materials as a function of cutting parameters and material strength.
Abstract: Machining of composite materials is an area full of open questions, such as chip formation and assessment of machinability, compared to metal cutting. Due to the peculiar nature of composite materials, sound analysis lacks progress yet. A study of drilling of reinforced thermoset and thermoplastics for characterizing their responses to machining is presented. The attained results are discussed in comparison with the theories of metal cutting. First of all, the chip characteristics are observed and found to reveal various cutting mechanisms of these two materials. One tends to fracture and the other demonstrates a considerable amount of plastic deformation. The further calculation of the specific cutting energy, with the acquired knowledge of deformation behavior in chip formation, provides information of the effort and size effect in machining of composite materials. Thermoset-based material requires a larger cutting force due to higher strength and is more responsive to chip size because of the sensitivity to micro defects in fracturing chips. The results are useful in establishing a mathematical model to predict torque and thrust in drilling of composite materials as a function of cutting parameters and material strength. The effects of fundamental cutting conditions on cutting force as well as on surface integrity of hole entrances, exit and walls are also investigated. Based on the above discussions, some aspects of chip characteristics and machinability of these materials are revealed.
136 citations
TL;DR: In this paper, a coupled model of the thermo-elastic-plastic material under large deformation for orthogonal cutting is constructed, and a chip separation criterion based on the critical value of the strain energy density is introduced into the analytical model.
Abstract: In this paper, a coupled model of the thermo-elastic-plastic material under large deformation for orthogonal cutting is constructed A chip separation criterion based on the critical value of the strain energy density is introduced into the analytical model A scheme of twin node processing and a concept of loading/unloading are also presented for chip formation The flow stress is taken as a function of strain, strain rate and temperature in order to reflect realistic behavior in metal cutting The cutting tool is incrementally advanced forward from an incipient stage of tool-workpiece engagement to a steady state of chip formation The finite difference method is adopted to determine the temperature distribution within the chip and tool, and a finite element method, which is based on the thermo-elastic-plastic large deformation model, is used to simulate the entire metal cutting process Finally, the chip geometry, residual stresses in the machined surface, temperature distributions within the chip and tool, and tool forces are obtained by simulation The calculated cutting forces agree quite well with the experimental results It has also been verified that the chip separation criterion value based on the strain energy density is a material constant and is independent of uncut chip thickness
TL;DR: In this paper, a series of turning tests were conducted on a number of different cutting-tool materials to machine an Al/25 vol% SiC metal-matrix composite and the influence of the cutting speed on the tool wear, the surface finish, and the cutting forces was established for each tool material.
TL;DR: A review of traditional machining methods applied to organic and metal matrix composites is presented in this article, where the use of non-traditional machining techniques such as waterjet, laser and ultrasonic machining is discussed in the second part.
TL;DR: The use of traditional machining methods was reviewed in Part I of this paper as discussed by the authors, where new methods are considered: laser, waterjet, electro-discharge, electrochemical spark, and ultrasonic machining.
TL;DR: In this paper, the main and post-processors were used to generate collision-free tool path data from collision avoidance procedure between a workpiece and an arbitrary tool shape based on the solid modeling technique.
TL;DR: In this article, high pressure flow was used, penetrating through the cutting tool's rake face and reducing the temperatures in the most critical area, in which chip symmetry simplifies fine analysis, and the narrowing and curling effect of the chip, improving chip exit from the slot, is viewed as related to temperature reduction.
Patent•
12 Mar 1992
TL;DR: In this paper, a tool path is automatically generated from CAD/CAM tool paths to represent the volume traversed by the cutting tool, and the material that remains to be machined is modeled and stored as new delta volumes.
Abstract: The present invention relates to processes for the automatic generation of numerical control (NC) tool paths in a CAD/CAM environment. The present invention operates on mechanical parts described as solid models. The process employs well-defined solid models of the part to be machined and the raw stock from which it will be machined. The volumetric difference between the stock and the part defines the material (delta volumes) that must be cut away during the actual machining process. Delta volumes are solid models, and users (or an expert system) can subdivide delta volumes into smaller volumes that are consistent with a manufacturing process plan. A delta volume and a user-defined strategy for machining the delta volume are then input to NC algorithms. The algorithms generate NC tool paths that remove as much delta volume material as possible. Tool volumes are automatically generated from NC tool paths to represent the volume traversed by the cutting tool. By subtracting the tool volume from the delta volume, the material that remains to be machined is modeled and stored as new delta volumes. The subtraction of the tool volume from the stock defines a new stock model that represents the incremental change in stock when the NC tool path is processed at the machine tool. The process is repeated until all delta volumes have been machined and the part has been manufactured.
TL;DR: In this article, different methods of creating and imaging small structures with an atomic force microscope (AFM) are reported, showing indentations, lines and more complex patterns created with three different techniques.
TL;DR: In this paper, the authors describe a system approach to the development of cantilever tooling structures (using the example of boring bars) which combine exceptionally high dynamic stability and performance characteristics with cost effectiveness.
Abstract: The least rigid components of machining systems are cantilever tools and cantilever structural units of machine tools (rams, spindle sleeves, etc.). These components limit machining regimes due to the development of chatter vibrations, limit tool life due to extensive wear of cutting inserts, and limit geometric accuracy due to large deflections under cutting forces. Use of high Young's modulus materials (such as sintered carbides) to enhance the dynamic quality of cantilever components has only a limited effect and is very expensive. This paper describes a systems approach to the development of cantilever tooling structures (using the example of boring bars) which combine exceptionally high dynamic stability and performance characteristics with cost effectiveness. Resultant success was due to: (1) a thorough survey of the state of the art; (2) creating a “combination structure” concept with rigid (e.g. sintered carbide) root segments combined with light (e.g. aluminum) overhang segments, thus retaining high stiffness and at the same time achieving low effective mass (thus, high mass ratios for dynamic vibration absorbers, or DVAs) and high natural frequencies; (3) using the concept of “saturation of contact deformations” for efficient joining of constituent parts with minimum processing requirements; (4) suggesting optimized tuning of DVAs for machining process requirements; (5) development of DVAs with the possibility of broad-range tuning; (6) structural optimization of the system; and (7) using a novel concept of a “Torsional Compliant Head”, or TCH, which enhances dynamic stability at high cutting speeds and is suitable for high rev/min applications since it does not disturb balancing conditions. The optimal performance and interaction of these concepts were determined analytically, and then the analytical results were validated by extensive cutting tests with both stationary and rotating boring bars, machining steel and aluminum parts. Stable performance with length-to-diameter ratios up to L/D = 15 was demonstrated, with surface finish 20–30 μm with both steel and aluminum at L/D = 7–11. Comparative tests with commercially available bars demonstrated the advantages of our system.
TL;DR: In this paper, a method of computer simulation based on a quasi-static computation has been proposed to analyze nanoscale cutting, where the cutting mechanism depends on both the crystalline orientation of a workpiece and the interatomic potential between the tool and workpiece materials.
TL;DR: In this article, a sculptured surface is denned by a non-uniform rational B-spline surface that provides the flexibility and freedom for surface description, and a decision on the process sequence in made based on the evaluated machining information.
Abstract: SUMMARY Sculptured surfaces often appear in mechanical parts of various industrial products as external form or the functional surface and are commonly found in moulds and dies. In this study a sculptured surface is denned by a non-uniform rational B-spline surface that provides the flexibility and freedom for surface description. Work proposed here includes the evaluation of machining information, decision for machining process sequence selection, and automatic cutter selection and path generation. Machining information is first evaluated by using series of hunt planes and calculating geometric shape, and constraints of the machining cavity. A decision on the process sequence in made based on the evaluated machining information. Cutter size is automatically determined by considering geometric constraints, maximum material removal rate in the roughing process, and minimum cutter movement with the required accuracy in the finishing process. Roughing is done by pocketing procedures that consider arbitrary s...
TL;DR: In this paper, a self-propelled rotary tool made of carbide exhibits superior wear-resistance comparable to the diamond tool, and the tool life of the tool has been extended dozens of times by rotary cutting.
TL;DR: In this article, a high-speed technique has been developed for machining three-dimensional silicon parts using laser-induced chlorine etching reactions, achieving removal rates exceeding 2×104 and ≥105 μm3/s at 1 and 15 μm x-y resolution, respectively.
Abstract: A high‐speed technique has been developed for machining three‐dimensional silicon parts using laser‐induced chlorine etching reactions. Parts are created directly from solid‐modeling computer‐aided‐design/computer‐aided‐manufacturing software. Removal rates exceeding 2×104 and ≥105 μm3/s are achieved at 1 and 15 μm x–y resolution, respectively. This is several orders of magnitude faster than electrodischarge machining methods. Submicrometer resolution has been achieved. Laser‐induced metallization of resulting structures as well as replication through compression molding have been demonstrated. A class of microfluidic flow‐channel devices is under development using a standard‐cell software architecture combined with field stitching.