Institute for Systems Research Technical Reports
Permanent URI for this collectionhttp://hdl.handle.net/1903/4376
This archive contains a collection of reports generated by the faculty and students of the Institute for Systems Research (ISR), a permanent, interdisciplinary research unit in the A. James Clark School of Engineering at the University of Maryland. ISR-based projects are conducted through partnerships with industry and government, bringing together faculty and students from multiple academic departments and colleges across the university.
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Item Control of Machining Induces Edge Chipping on Glass Ceramics(1996) Ng, S.J.; Le, Dung T.; Tucker, S.R.; Zhang, G.M.; ISREdge chipping is a phenomenon commonly observed during the machining of ceramic material. Characterization of edge chipping, both in macro and in micro scale, and correlating its formation to machining parameters form a basis for developing new and innovative technologies for controlling in machining induced damage. An experimental-based study using glass ceramic material is performed. Three types of edge chipping are identified. The SEM-sterephotography method and the finite element method are used to evaluate the edge chipping effect under a set of machining conditions. Significant findings are obtained and guidelines for controlling edge chipping during machining are suggested.Item Characterization of the Surface Texture Formed During the Machining of Ceramics(1995) Zhang, G.M.; Ng, S.J.; Le, Dung T.; Job, Lenox S.; ISRThis paper presents the development of a computer-based system to perform characterization of the surface texture formed during the machining of ceramic material. Techniques of image processing and computer graphics are employed to display vivid pictures of micro-scale details of the machined surfaces. Special attention is given to establishing the interrelations between the surface texture formation and the grain facet fracture induced by machining. Results obtained from microscopic analysis of the formed surface texture reveal that grain pullouts and cleavage, as a result of the progressive development of grain boundary micro-cracking, are two mechanisms responsible for the material removal process. The surface texture is an aggregation of macro and micro-scale fractured facets. A new performance index cavity density is introduced to quantify the combinational effect of material microstructure and the dynamic loading during machining on the micro-mechanisms of the material removal process.Item Characterization of the Surface Cracking Formed during the Machining of Ceramic Material(1995) Zhang, G.M.; Ng, S.; Le, Dung T.; ISRThis paper presents a method to characterize the surface cracking formed during the machining of ceramics material. Ceramic specimens are prepared under two different machining environments, dry and submersion. An environmental scanning electron microscope is used to obtain high-magnification images of machined surfaces. Reconstruction of the surface texture in a three-dimensional space is made by scanning the images and using graphics software to obtain detailed and informative spatial views of the machined surface. The visualized surface cracks provide quantitative information on their size and shape. Two performance indices are proposed to characterize the distribution of surface cracks induced by machining in terms of the density and crack depth with reference to the machined surface. As a case study, the developed nondestructive evaluation method is used to assess the effectiveness of using the submerged machining to process ceramic material. The obtained results present a clear picture illustrating the capability of controlling the crack formation during the submerged machining.Item Submerged Precision Machining of Ceramic Material(1995) Zhang, G.M.; Ko, Wing F.; Ng, S.; ISRThe brittle nature of ceramics makes them difficult to machine. This paper presents a study to explore a new method to machine ceramic material. The method is based on the stress-corrosion- cracking behavior of ceramic material under certain aggressive environments. An apparatus is designed to create a machining environment where workpiece and cutting tool are submerged in a bath filled with cutting fluids. Observations on the surface texture formed during machining have been made to investigate the effectiveness of submerged machining on quality and efficiency of the machining operation. The obtained results strongly suggest that the chemo-mechanical interactions occurred during machining have great influence on the stress distribution produced in the ceramic material being machined, thus have direct effects on crack initiation and propagation. By controlling the machining parameters, higher material removal rate with less surface damage can be achieved, showing the potential of submerged machining as an innovative technology for machining ceramic material.Item The Mechanics of Material Removal Mechanisms in the Machining of Ceramics(1994) Zhang, G.M.; Satish, K.G.; Ko, Wing F.; ISRThis paper presents a study on the mechanics of material removal for ceramic materials by observing single-point turning process of aluminum oxide (Al2O3). On-line cutting force measurement is performed and the surface integrity is characterized off-line by examining the surface texture. A theoretical analysis of fracture mechanics provides a comprehensive understanding of the chip formation process, and a model describing the material removal mechanisms is discussed. Based on the model, a systematic investigation of the chip fragments formed during machining is performed.Item Development of Variant Designs in ISO 9000 Certification(1993) Woo, M.; Zhang, G.M.; ISRThis paper will present the research results from developing a computer database system using a variant design approach to assist in the preparation of quality manuals. The basic principle is "the most common one of design assignments modifies or uses an existing design to make a 'new' component." Such an information flow mainly relies on a database, which stores all the information about ISO 9000 certification requested by a desired company. Integration of system architecture and communication protocol allows to accommodate different types of business (electronics, mechanical, etc.). A case study is presented to illustrate the process of generating quality manuals through an intelligent user-interface and to demonstrate a new and unique business strategy to enhance quality improvement and management.Item Building MRSEV Models for CAM Applications(1993) Gupta, Satyandra K.; Kramer, Thomas R.; Nau, D.S.; Regli, W.C.; Zhang, G.M.; ISRIntegrating CAD and CAM applications, one major problems is how to interpret CAD information in a manner that makes sense for CAM. Our goal is to develop a general approach that can be used with a variety of CAD and CAM applications for the manufacture of machined parts.In particular, we present a methodology for taking a CAD model, extracting alternative interpretations of the model as collections of MRSEVs (Material Removal Shape Element Volumes, a STEP-based library of machining features), and evaluating these interpretations to determine which one is optimal. The evaluation criteria may be defined by the user, in order to select the best interpretation for the particular application at hand.
Item Optical Area-Based Surface Quality Assessment for In-Process Measurement(1993) DeVoe, Don L.; Zhang, G.M.; ISRThe measurement of surface finish has been recognized as an important element of Computer Integrated Manufacturing (CIM) systems which perform on-line machining systems control. Optical methods for the in-process measurement of surface roughness have been developed for this purpose, but these systems have in many cases introduced excessive complexity in the CIM system. This work presents an area-based surface characterization technique which applies the basic light scattering principles used in other optical measurement systems. These principles are applied in a novel fashion which is especially suitable for in-process measurement and control. A prototype of the optical system to implement these principles is developed in this work. The experimental results are presented to demonstrate the capabilities and future potential for integrating the measurement system into a machining process to achieve significant improvement of quality and productivity.Item Interpreting Product Designs for Manufacturability Evaluation(1993) Gupta, Satyandra K.; Nau, D.S.; Zhang, G.M.; ISRThe ability to quickly introduce new quality products is a decisive factor in capturing market share. Because of pressing demands to reduce lead time, analyzing the manufacturability of the proposed design has become an important step in the design stage. In this paper we present an approach for evaluating the manufacturability of machined parts.Evaluating manufacturability involves finding a way to manufacture the proposed design, and estimating the associated production cost and quality. However, there often can be several different ways to manufacture a proposed design - so to evaluate the manufacturability of the proposed design, we need to consider different ways to manufacture it, and determine which one best meets the manufacturing objectives.
In this paper we describe a methodology for systematically generating and evaluating alternative operation plans. As a first step, we identify all machining operations which can potentially be used to create the given design. Using these operations, we generate different operation plans for machining the part. Each time we generate a new operation plan, we assign it a manufacturability rating. The manufacturability rating for the design is the rating of the best operation plan.
We anticipate that by providing feedback about possible problems with the design, this work will be useful in providing a way to speed up the evaluation of new product designs in order to decide how or whether to manufacture them.
Item Estimation of Achievable Tolerances(1993) Gupta, Satyandra K.; Nau, D.S.; Zhang, G.M.; ISRThis report presents a new and systematic approach to assist decision-making in selecting machining operation plans. We present a methodology to estimate achievable tolerances of operations plan. Given an operation plan, we use variety of empirical and mathematical models to evaluate process capabilities of various machining operations and compute achievable tolerances using tolerance charting techniques.