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Ozel T.,Rutgers University | Sima M.,Rutgers University | Srivastava A.K.,TechSolve Inc. | Kaftanoglu B.,Atilim University
CIRP Annals - Manufacturing Technology | Year: 2010

This paper presents investigations on turning Ti-6Al-4V alloy with multi-layer coated inserts. Turning of Ti-6Al-4V using uncoated, TiAlN coated, and TiAlN + cBN coated single and multi-layer coated tungsten carbide inserts is conducted, forces and tool wear are measured. 3D finite element modelling is utilized to predict chip formation, forces, temperatures and tool wear on these inserts. Modified material models with strain softening effect are developed to simulate chip formation with finite element analysis and investigate temperature fields for coated inserts. Predicted forces and tool wear contours are compared with experiments. The temperature distributions and tool wear contours demonstrate some advantages of coated insert designs. © 2010 CIRP. Source

Siegel D.,Intelligent Maintenance | Al-Atat H.,Intelligent Maintenance | Shauche V.,Intelligent Maintenance | Liao L.,Intelligent Maintenance | And 2 more authors.
Mechanical Systems and Signal Processing | Year: 2012

The assessment and diagnosis of bearing health using vibration data has been a research topic of interest for many years and includes developments in an assortment of signal processing methods and classification algorithms. This paper investigates detecting bearing degradation at different levels of damage, in that estimating the bearing health at the various stages of degradation is important for predicting failure as well as making maintenance decisions. The proposed technique does not require a measure of the rotational shaft speed or bearing cage speed, which makes it very suitable in certain applications in which it is very difficult or not cost effective to measure the rotational speed. To effectively estimate the bearing health state, a novel tachometer-less synchronously averaged envelope (TLSAE) signal processing and feature extraction technique for rolling element bearing is proposed. The Tachometer-Less Synchronous Averaged Envelope (TLSAE) method consists of first using a narrow band pass filter around a calculated bearing fault frequency of interest and using the derivative of the phase of the Hilbert Transform of this narrow band signal to generate a synthesized tachometer signal that is representative of the impact due to a bearing defect. This synthesized tachometer signal is combined with the high frequency envelope method to perform synchronous averaging on the envelope signal, resulting in a defect synchronous envelope spectrum in which the frequency content is in terms of the fault frequency orders. The proposed method is further compared and evaluated with other existing methods, in particular to the traditional Fourier Transform technique, the bearing envelope analysis technique, and the empirical mode decomposition signal processing methods on the basis of whether each method provides an enhanced level of indication that can determine the health of rolling element bearings. Data from a bearing test-rig is used to facilitate the comparison and evaluation of the signal processing methods. Vibration data was collected from the test-rig for bearings with different levels of degradation. The calculated vibration features from the tachometer-less synchronously averaged envelope (TLSAE) technique are compared to the other feature extraction techniques; with the synchronous average method providing a set of bearing vibration features that can distinguish all three levels of damage on the outer race of the rolling element bearing. Future work looks to further investigate this proposed technique for data collected during a run to failure test in order to consider its merits for early detection of incipient bearing damage and whether it provides a consistent monotonic trend from spall initiation to bearing failure. © 2012 Elsevier Ltd. Source

Yamaguchi H.,University of Florida | Srivastava A.K.,TechSolve Inc. | Tan M.A.,University of Florida | Riveros R.E.,University of Florida | Hashimoto F.,Timken Co.
CIRP Annals - Manufacturing Technology | Year: 2012

Uncoated carbide tool surfaces are conditioned using magnetic abrasive finishing (MAF) to improve the tool wear characteristics by reducing friction between the tool and chip. The configuration of the magnetic particle chains that drive the abrasives plays an important role in surface finishing with minimal damage to the tool cutting edges. Roughnesses of less than 25 nm Ra on the flank and nose and less than 50 nm Ra on the rake can be achieved. In turning of Ti-6Al-4V alloy rods (at 100 m/min cutting speed), MAF-processed tools exhibited tool lives of up to twice as long as unprocessed tools. © 2012 CIRP. Source

Atluru S.,University of Cincinnati | Huang S.H.,University of Cincinnati | Snyder J.P.,TechSolve Inc.
International Journal of Advanced Manufacturing Technology | Year: 2012

Machine tools and machining systems have gone through significant improvements in the past several decades. Recent advance in information technology made it possible to collect and analyze a large amount of data in real time. This brings about the concept of a smart machine tool, enabled by process monitoring and control technologies, to produce the first and all subsequent parts correctly. This paper presents a system framework for a smart machine supervisory system. The supervisory system integrates individual technologies and makes overall intelligent decisions to improve machining performance. The communication mechanism of the supervisory system is discussed in detail. Its decision-making mechanism is illustrated through an example that integrates process planning, health maintenance, and tool condition monitoring. © 2011 Springer-Verlag London Limited. Source

Srivastava A.K.,University of Texas-Pan American | Pavel R.,TechSolve Inc.
International Journal of Mechatronics and Manufacturing Systems | Year: 2015

The effect of various grinding parameters on the surface integrity of titanium (Ti-6Al-4V) alloy specimens produced using direct metal laser sintering (DMLS®) process have been studied. The goal has been to identify the safe grinding parameters that would result in ground surfaces free of defects such as micro-cracks, discoloration, and/or burn marks which occur due to localised high heat generated during grinding. The residual stresses have been used to quantify the effect of grinding parameters on the ground surface. The experimental results show that the grinding parameters within the range of 10.2 m/s-20.3 m/s wheel speed, 12.2 m/min-14.7 m/min feed rate, and a depth of cut smaller than 0.025 mm, with the condition that any of the combination of these parameters leading to an equivalent chip thickness lower than 0.254 μm, and a specific material removal rate lower than 4.3 mm3/s/mm will provide compressive residual stresses and can be used as safe grinding parameters. Copyright © 2015 Inderscience Enterprises Ltd. Source

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