@article{sheikh-ahmad_quarless_bailey_2004, title={On the role of microcracks on flow instability in low speed machining of CP titanium}, volume={8}, ISSN={["1532-2483"]}, DOI={10.1081/LMST-200039867}, abstractNote={Abstract Flow instability is observed when machining titanium and its alloys and leads to the localization of plastic deformation into narrow bands. The shear strain at which this localization occurs serves as an important design parameter that measures the workability of a material and its suitability for various applications. In the current investigation, the phenomenon of microcracking during chip formation of grade 2 commercially pure (CP) titanium has been examined as a mechanism that promotes flow instability at low speeds. Based on this study, analytical and descriptive models that have been previously proposed for predicting the onset of flow instability have been revised to account for microcracking. Model predictions were experimentally verified for the orthogonal machining of CP titanium over a wide range of cutting speeds. Additionally, an investigation of plastic deformation across microcracks and localized shear zones was conducted in an effort to better understand strain hardening during chip formation.}, number={3}, journal={MACHINING SCIENCE AND TECHNOLOGY}, author={Sheikh-Ahmad, JY and Quarless, V and Bailey, JA}, year={2004}, month={Nov}, pages={415–430} } @article{sheikh-ahmad_lewandowski_bailey_stewart_2003, title={Experimental and numerical method for determining temperature distribution in a wood cutting tool}, volume={16}, ISSN={["0891-6152"]}, DOI={10.1080/08916150390223092}, abstractNote={A 2-D boundary-element model was used to solve the steady-state heat conduction problem in a wood cutting tool. Cutting experiments were conducted in order to measure temperatures at remote locations on the tool rake face and at the tool/holder interface. The tool/holder interface temperatures were used as inputs into the boundary-element model. Heat input into the tool was adjusted until predicted temperatures on the rake face agreed with experimental results. The proportion of the machining power conducted into the tool as heat was determined as a function of the cutting geometry, specific cutting energy, and cutting speed.}, number={4}, journal={EXPERIMENTAL HEAT TRANSFER}, author={Sheikh-Ahmad, JY and Lewandowski, CM and Bailey, JA and Stewart, JS}, year={2003}, pages={255–271} } @article{raghuveer_yoganand_jagannadham_lemaster_bailey_2002, title={Improved CVD diamond coatings on WC-Co tool substrates}, volume={253}, ISSN={["0043-1648"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0036951335&partnerID=MN8TOARS}, DOI={10.1016/S0043-1648(02)00244-2}, abstractNote={Tungsten carbide tools with different cobalt concentrations (3 and 6%) have been treated with different surface cleaning procedures for deposition of diamond and multilayer diamond composite films. Cleaning with organic solvents, surface etching to remove cobalt from the surface, and hydrogen plasma etching to decarburize WC and etch remove cobalt have been used in combination to improve the adhesion of diamond films deposited on the tool substrates. Diamond layers are deposited by microwave plasma chemical vapor deposition (MPCVD) after introducing surface nucleation by suspension with sub-micron size diamond crystallites. TiN and TiC films are deposited as intermediate layers that prevent diffusion of cobalt or as embedding layers that also anchor diamond crystallites to the tool substrate. A continuous top layer of diamond was deposited for different periods of time (15–36 h) to obtain diamond film thickness ranging from 15 to 36 μm. The performance of diamond-coated tools has been tested by machining particleboard. The tool surfaces were characterized using measurements of wear of the cutting edge. Microstructural characterization using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) of the composite layers on the tool surfaces is performed. The quantitative evaluation of wear and microstructural characterization were used to determine the mechanisms of wear of the cutting edge. The results are used to conclude the diamond tool coating procedure that provides the best performance in machining particleboard.}, number={11-12}, journal={WEAR}, author={Raghuveer, MS and Yoganand, SN and Jagannadham, K and Lemaster, RL and Bailey, J}, year={2002}, month={Dec}, pages={1194–1206} } @misc{sheikh-ahmad_bailey_1999, title={High-temperature wear of cemented tungsten carbide tools while machining particleboard and fiberboard}, volume={45}, ISSN={["1611-4663"]}, DOI={10.1007/BF00538952}, abstractNote={Published research on the wear processes of cemented tungsten carbide tools used for machining reconstituted wood products was reviewed, and the current state of knowledge in this area was evaluated. Underlying assumptions and conclusions regarding high-temperature oxidation/corrosion wear during machining were examined in view of known reaction kinetics of cemented tungsten carbide alloys in oxidative and corrosive environments at temperatures that may occur at the cutting edge. This examination indicated that some wear mechanisms other than high-temperature oxidation/corrosion are likely to be rate-controlling when machining reconstituted wood products such as particleboard and fiberboard.}, number={6}, journal={JOURNAL OF WOOD SCIENCE}, author={Sheikh-Ahmad, JY and Bailey, JA}, year={1999}, pages={445–455} } @article{sheikh-ahmad_bailey_1999, title={The wear characteristics of some cemented tungsten carbides in machining particleboard}, volume={225}, ISSN={["1873-2577"]}, DOI={10.1016/s0043-1648(98)00361-5}, abstractNote={This work is focused on developing an understanding of the wear mechanisms of cemented tungsten carbide tools in machining particleboard. Cutting experiments were conducted on several grades of cemented tungsten carbide tools using a high speed lathe, and their wear characteristics were determined. It was found that wear occurred predominantly on the clearance face of the tools for most grades tested. It was also found that the amount of wear after the same cutting distance correlates well with the bulk hardness of the tool material. The amount of wear generally decreased with an increase in hardness, a decrease in grain size and a decrease in binder content of the cutting tool material. Examination of the worn surfaces inside a scanning electron microscope showed that the cutting edge was worn by preferential removal of the metal binder phase from between the tungsten carbide grains. It is suggested that removal of the binder weakens the bond between the tungsten carbide grains leading to their mechanical removal from the clearance face. It is concluded that the main wear mechanism for cemented tungsten carbide tools in machining particleboard is the removal of the binder phase by plastic flow and micro-abrasion, which is followed by fragmentation and dislodging of the WC grains.}, journal={WEAR}, author={Sheikh-Ahmad, JY and Bailey, JA}, year={1999}, month={Apr}, pages={256–266} } @article{kato_bailey_1998, title={Wear characteristics of a woodworking knife with a vanadium carbide coating only on the clearance surface (back surface)}, volume={138-1}, ISSN={["1013-9826"]}, DOI={10.4028/www.scientific.net/kem.138-140.479}, journal={ADVANCED CERAMIC TOOLS FOR MACHINING APPLICATION - III}, author={Kato, C and Bailey, JA}, year={1998}, pages={479–520} } @article{sheikhahmad_bailey_1997, title={Flow instability in the orthogonal machining of CP titanium}, volume={119}, ISSN={["1528-8935"]}, DOI={10.1115/1.2831108}, abstractNote={An experimental and analytical investigation of flow instability and shear localization in the orthogonal machining of grade 2 commercially pure titanium was made. A criterion for thermo-plastic instability was developed from torsion test results and applied to the analysis of the chip formation process. It was shown that flow instability followed by flow localization occurs when machining titanium at all cutting speeds and that a transition in the chip type from uniform to segmented does not occur. Orthogonal machining experiments were conducted in the speed range from 8.75 × 10−5 to 3.20 m/s for various depths of cut and the shear strain in the chip was calculated. It was shown that shear localization occurred in the chip formation process when the uniform shear strain involved in producing a chip segment reached a critical value and that this critical shear strain correlates fairly well with the instability shear strain predicted by the thermo-plastic instability criterion.}, number={3}, journal={JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME}, author={SheikhAhmad, J and Bailey, JA}, year={1997}, month={Aug}, pages={307–313} }