One method for creating broken chips in turning processes involves oscillating the cutting tool in the feed direction utilizing the CNC machine axes. The University of North Carolina at Charlotte and the Y-12 National Security Complex have developed and are refining a method to reliably control surface finish and chip length based on a particular machine’s dynamic performance. Using computer simulations it is possible to combine the motion of the machine axes with the geometry of the cutting tool to predict the surface characteristics and map the surface texture for a wide range of oscillation parameters. These data allow the selection of oscillation parameters to simultaneously ensure broken chips and acceptable surface characteristics. This paper describes the machine dynamic testing and characterization activities as well as the computational method used for evaluating and predicting chip length and surface texture.

Turning operations involving depleted uranium frequently generate long, stringy chips that present a hazard to both the machinist and the machine tool. While a variety of chip-breaking techniques are available, they generally depend on a mechanism that increases the bending of the chip or the introduction of a one dimensional vibration that produces an interrupted cutting pattern. Unfortunately, neither of these approaches is particularly effective when making a 'light depth-of-cut' on a contoured workpiece. The historical solution to this problem has been for the machinist to use long-handled tweezers to 'pull the chip' and try to keep it submerged in the chip pan; however, this approach is not practical for all machining operations. This paper discusses a research project involving the Y-12 National Security Complex and the University of North Carolina at Charlotte in which unique, oscillatory part programs are used to continuously create an interrupted cut that generates pre-defined, user-selectable chip lengths.

Past work at UNC Charlotte has demonstrated that the use of oscillating CNC toolpaths provides a reliable chip breaking alternative to conventional methods such as the use of cutting inserts with special geometries and/or adjusting machining parameters. The specific toolpath geometry and the selection of the oscillating parameters is an important step to reliably and constantly create broken chips using this new method. This paper builds on the past work and discusses the proper selection of oscillation amplitude and its effect on the ability to break chips and to achieve desired chip lengths.

INTRODUCTION Turning operations involving ductile materials frequently generate long, stringy chips that present a hazard to both the machinist and the machine tool. In addition, the post-machining handling of stringy chips is a potentially dangerous and often expensive endeavor. While a variety of chip-breaking techniques are available, they generally depend on a mechanism for increasing the bending of the chip or the introduction of a one dimensional vibration that produces an interrupted cutting pattern. Unfortunately, neither of these approaches is particularly effective when making a “light depth-of-cut” on a contoured workpiece. This paper discusses a research project involving the Y-12 National Security Complex and the University of North Carolina at Charlotte in which unique, oscillatory part programs are used to continuously create an interrupted cut that generates pre-defined, user-selectable chip lengths [1, 2].

The creation of oscillating tool paths for turning operations that use the numerically controlled machine axes to ensure reliable chip breaking has been demonstrated in a variety of materials. The interrupted cuts created in this way have the additional benefit of allowing the temperature of the tool-chip interface to be controlled at a significantly lower level than in conventional turning. In traditional continuous turning, the interface temperature rises to a high level and stays there during machining. This is especially a problem for difficult-to-machine materials, because many tool wear mechanisms are strongly temperature dependent. In the chip breaking tool paths, the axes of the machine are used to oscillate the tool along the programmed tool path, and before the temperature has a chance to rise to damaging levels, the cut can be interrupted so that the tool can cool. This is analogous to the technique of using shallow radial depths of cut in milling operations for difficult-to-machine materials. In this work, a thermal imaging camera is used to verify that this strategy can be effective in the machining of steel. The results from the thermal imaging studies show that over a broad range of conditions, oscillating tools paths create lower temperatures at the tool-chip interface.

Finish machining operations contribute the majority of the costs associated with fabricating high quality ceramic products. These components are typically used in harsh environments such as diesel engines, the defense industry, and automotive applications. The required finishing operations involve a variety of technology areas including process controls, process analysis, product certification, etc. and are not limited only to component grinding methods. The broad range of manufacturing problem solving expertise available in Oak Ridge provided resources that were far beyond what is available to the Coors manufacturing sites. Coors contributed equipment, such as the computer controls and part handling mechanisms associated with a state-of-the-art inspection machine plus operation-specific experience base. In addition, addressing these challenging tasks enabled Oak Ridge personnel to maintain familarity with rapidly advancing technologies, such as those associated with machine vision equipment, process monitoring techniques, and computer control systems.

The purpose of the CEMOC program was to support U.S. industry needs in fabricating precision components, from difficult to machine materials, while maintaining and enhancing the precision manufacturing skills of the Oak Ridge Complex. Oak Ridge and partner company personnel worked in a team relationship wherein each contributed equally to the success of the program. In general, Oak Ridge contributed a wider range of expertise to a given task while the companies provided operations-specific equipment and shop-floor services. Process control technologies, machining procedures and parameters, and coolant-related environmental tasks were the primary focus areas. The companies were very pleased with the results of the CRADAs and are planning on continuing the relationships. Finish machining operations contribute the majority of the costs associated with fabricating high quality ceramic products. These components are typically used in harsh environments such as diesel engines, defense machinery, and automotive components. The required finishing operations involve a variety of technologies including process controls, machine coolants, product certification, etc. and are not limited only to component grinding methods. The broad range of manufacturing problem solving expertise available in Oak Ridge provided resources that were far beyond what are typically available to the CRADA partners. These partners contributed equipment, such as state-of-the-art machine tools, and operation-specific experience base. In addition, addressing these challenging tasks enabled Oak Ridge personnel to maintain familiarity with rapidly advancing technologies, such as those associated with computer control systems.

A Ceramic Technology Project was initiated at the Oak Ridge National Laboratory (ORNL) in 1983 to develop an industry technology base for reliable, high temperature ceramics for use in advanced engines such as the ceramic gas turbine and low heat rejection, heavy-duty truck engines. The plan for this project was developed jointly by industry, academia, and the US Government. The plan was developed following a needs assessment which determined the critical technology base requirements, the potential economic value of structural ceramics, the extent of ongoing and planning research and development programs, and the estimated funding that would be required. The High Temperature Materials Laboratory (HTML) at ORNL serves as a focal point for the Ceramic Technology Project. HTML activities are designed to address the high-temperature materials problems that limit the efficiency and reliability of advanced energy conversion systems and to assist US industry in meeting the challenge of foreign competition. The HTML also functions as a user facility for industrial and university researchers. It contains the special research equipment that is needed to characterize a material`s microstructure and microchemistry as well as physical and mechanical properties. This report discusses the cost effectiveness of ceramic manufacturing at the MTDC.

For a number of years, the Oak Ridge Y-12 Plant has been involved in an endeavor which is described as a Precision Flexible Manufacturing System (PFMS). The objective of this project is to enhance the existing manufacturing operations for the production of precision hemispherical workpieces. The present fabrication process uses T-base lathes, similar to the one shown in figure 1, which are equipped with a Computer Numerical Control (CNC) system. The CNC systems are coupled to a host computer over a local area network (LAN). Currently, this link is used to download machining part programs and upload limited process information. While the enhanced system will use the same machine tools and LAN, additional capabilities will be provided to perform automatic tool changing, part and fixture handling, on-machine gagging, and chip control. The project's quality goals are to automatically manufacture workpieces to tolerances of +/- 0.0005 in. on contour and +/- 0.001 in. on wall thickness with a 3 to 5 sigma level of confidence. The parts will range from 4 to 10 in. in diameter with a wall thickness as large as one inch. 2 refs., 6 figs.

This book provides a common sense computer-oriented, determinstic manufacturing approach, which employs statistics but does not require a background in this area, theoretical mathematics or computer science to understand and apply. In a clear, easy-to-read style, this reference text highlights critical parameters that have a major impact upon process quality and identifies sensors for parameter monitoring; discusses appropriate applications of deterministic techniques to many manifacturing situations ranging from simple to complex; includes chapter summaries, helpful illustrations and numerous citations to ehnance comprehension and facilitate further research. Written from the perspective of a practioner who 'knows how to make parts'; presenting practical solutions to manufacturing problems it is essential reading for industrial, quality control, electrical and electronics, mechancial, manufacturing and systems engineers/managers and undergraduate and graduate-level students in the above areas.