The Experts below are selected from a list of 2931 Experts worldwide ranked by ideXlab platform
Chinedum E. Okwudire - One of the best experts on this subject based on the ideXlab platform.
-
Optimal damping for the reduction of residual vibrations in ultra-Precision Manufacturing machines
2020Co-Authors: Chinedum E. OkwudireAbstract:BACKGROUND Ultra-Precision Manufacturing (UPM) machines are designed to fabricate and measure complex parts having micrometer-level features and nanometer-level tolerances/surface finishes [1]. Examples of UPM machines include ultraPrecision machine tools, wafer steppers and micro CMMs. UPM machines are often isolated from floor vibrations using passive isolators because they are cost effective, reliable and energy neutral [2][3]. A major problem with the soft mounting provided by passive isolators is that it induces low-frequency residual vibrations of the isolated machine base, which degrades the achievable accuracy/speed of UPM machines [2]. A long-standing rule of thumb in isolation system design is to decouple all vibration modes by aligning the isolator mounting locations with the center of gravity (CG) of the isolated machine [4]. In practice, however, many UPM machine designs are mode coupled because it is very difficult to locate the isolators exactly at the CG [3]. Moreover, recent research by the authors has revealed that mode coupling can lead to the drastic reduction of residual vibrations in passively isolated systems [5]. The problem however is that mode coupling complicates the damping behavior of the isolated machine, compared to the decoupled system which has a predictable damping behavior. Consequently, there is a need to provide UPM designers with the analytical tools and practical guidelines to select vibration isolator damping values that provide the best reduction of residual vibrations for mode coupled systems.
-
reduction of vibrations of passively isolated ultra Precision Manufacturing machines using mode coupling
Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology, 2016Co-Authors: Chinedum E. OkwudireAbstract:Abstract Ultra-Precision Manufacturing (UPM) machines are used to fabricate and measure complex parts having micrometer-level features and nanometer-level tolerances/surface finishes. Therefore, random vibration of the machine due to ground excitations and residual vibration stemming from onboard disturbances must be mitigated using vibration isolation systems. A long-standing rule of thumb in vibration isolation system design is to locate the isolators in such a way that the vibration modes of the isolated machine are decoupled. However, prior work by the authors has demonstrated that coupling vibration modes of passively-isolated UPM machines could provide conditions for drastic reduction of residual vibrations compared to decoupling. The authors’ analysis was based on the restrictive assumption that the isolated machine was modally damped. The key contribution of this paper is in investigating the effect of mode coupling on the residual vibrations of UPM machines with non-proportional (NP) damping—which is more realistic than modal damping. It also analyzes the effects of mode coupling on the reduction of ground vibrations (i.e., transmissibility). The analyses reveal that, even though NP damping changes the vibration behavior of the machine compared to modal damping, mode coupling still provides ample opportunities to reduce residual vibration and transmissibility. Guidelines for properly designing a UPM machine to best exploit mode coupling for vibration reduction are provided and validated through simulations and experiments. Up to 40% reduction in residual vibration and 50% reduction in transmissibility are demonstrated.
-
Effects of Non-Proportional Damping on the Residual Vibrations of Mode-Coupled Ultra-Precision Manufacturing Machines
Volume 3: Industrial Applications; Modeling for Oil and Gas Control and Validation Estimation and Control of Automotive Systems; Multi-Agent and Netwo, 2014Co-Authors: Chinedum E. OkwudireAbstract:Ultra-Precision Manufacturing (UPM) machines are used to fabricate and measure complex parts having micrometer-level features and nanometer-level tolerances/surface finishes. Therefore, low-frequency residual vibrations that occur during the motion of the machines’ axes must be minimized. Recent work by the authors has revealed that coupling vibration modes of passively-isolated UPM machines can provide conditions for drastic reduction of residual vibrations vis-a-vis the recommended practice of modal decoupling. This paper presents an investigation into the effects of non-proportional (NP) damping on the conclusions reached in the authors’ prior work. With NP damping added, the conditions under which mode coupling is beneficial relative to decoupling are seen to remain largely the same. However, NP damping is shown to significantly influence the conditions under which the system’s response is most sensitive to mode coupling. Design guidelines for maximally exploiting the benefits of mode coupling are presented and demonstrated experimentally on a UPM machine.Copyright © 2014 by ASME
-
Optimal Motor Location for the Reduction of Residual Vibrations in Mode-Coupled Ultra-Precision Manufacturing Machines
Volume 2: Systems; Micro and Nano Technologies; Sustainable Manufacturing, 2013Co-Authors: Chinedum E. OkwudireAbstract:1 Contact Author ABSTRACT Ultra-Precision Manufacturing (UPM) machines are used to fabricate and measure complex parts having micrometer-level features and nanometer-level tolerances/surface finishes. Therefore, low-frequency residual vibrations that occur during the motion of the machines' axes must be minimized. Recent research by the authors has revealed that coupling the vibration modes of passively-isolated machines by properly selecting the location of the vibration isolators could lead to a drastic reduction in residual vibrations. However, the effect of motor location on the residual vibrations of mode-coupled UPM machines has not been rigorously analyzed. In this paper, an objective function which minimizes residual vibration energy with respect to motor location is defined and analyzed. It is shown to have a guaranteed global minimum irrespective of the parameters of the UPM machine. Conditions that ensure that the global minimum is located in a practically feasible design space are explored. Finally, the merits of optimal motor placement on residual vibration reduction are demonstrated using simulations conducted on a 5-axis ultra-Precision machine tool.
-
minimization of the residual vibrations of ultra Precision Manufacturing machines via optimal placement of vibration isolators
Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology, 2013Co-Authors: Chinedum E. OkwudireAbstract:Abstract Ultra-Precision Manufacturing (UPM) machines are used to fabricate and measure complex parts having micrometer-level features and nanometer-level tolerances/surface finishes. Consequently, low-frequency residual vibrations that occur during the motion of the machines’ axes must be mitigated. A long-standing rule of thumb in vibration isolation system design is to locate the isolators in such a way that all vibration modes are decoupled. This paper uses the 2D dynamics of a passively isolated system to show that coupling the vibration modes of the isolated system by altering the location of the isolators provides conditions which allow for the drastic reduction of residual vibrations. An objective function which minimizes residual vibration energy is defined. Perturbation analyses of the objective function reveal that the recommended practice of decoupling the vibration modes more often than not leads to sub-optimal results in terms of residual vibration reduction. The analyses also provide guidelines for correctly locating the isolators so as to reduce residual vibrations. Simulations and experiments conducted on a passively isolated ultra-Precision machine tool are used to validate the findings of the paper; a 5-fold reduction of the dominant residual vibrations of the machine tool is achieved without sacrificing vibration isolation quality (i.e., transmissibility).
David Dornfeld - One of the best experts on this subject based on the ideXlab platform.
-
Precision Manufacturing of Imprint Rolls for the Roller Imprinting Process
2008Co-Authors: Athulan Vijayaraghavan, David DornfeldAbstract:The roller imprinting process is being developed for the efficient and accurate fabrication of microfluidic devices. As the Precision of the imprinted features is dependent on the features of the imprint rolls used in the process, it is critical that the rolls are manufactured very accurately, conforming closely to their design. It is also important that imprint rolls are manufactured rapidly and cost-effectively to control the cost and lead-time of roller imprinting. This paper looks at the application of micromachining technology in the Manufacturing of imprint rolls. Sources of error during the Manufacturing process are identified, and their effect on the Precision of the final imprinted feature is discussed. Toolpath planning strategies are presented for generating very smooth surfaces. The paper presents a framework of Precision Manufacturing requirements for the roller imprinting process.
-
Precision Manufacturing process monitoring with acoustic emission
International Journal of Machine Tools & Manufacture, 2006Co-Authors: I Hwang, C M O Valente, Joao Fernando Gomes De Oliveira, David DornfeldAbstract:Abstract Current demands in high-technology industries such as semiconductor, optics, MEMS, etc. have predicated the need for Manufacturing processes that can fabricate increasingly smaller features reliably at very high tolerances. In situ monitoring systems that can be used to characterize, control, and improve the fabrication of these smaller features are therefore needed to meet increasing demands in Precision and quality. This paper discusses the unique requirements of monitoring of Precision Manufacturing processes, and the suitability of acoustic emission (AE) as a monitoring technique at the Precision scale. Details are then given on the use of AE sensor technology in the monitoring of Precision Manufacturing processes; grinding, chemical–mechanical planarization (CMP) and ultraPrecision diamond turning in particular.
-
Precision Manufacturing Process Monitoring with Acoustic Emission - eScholarship
2006Co-Authors: I Hwang, C M O Valente, J. F.g. Oliviera, David DornfeldAbstract:International Journal of Machine Tools & Manufacture 46 (2006) 176–188 www.elsevier.com/locate/ijmactool Precision Manufacturing process monitoring with acoustic emission D.E. Lee a , I. Hwang a , C.M.O. Valente b , J.F.G. Oliveira b , D.A. Dornfeld a, * a Laboratory for Manufacturing Automation, Department of Mechanical Engineering, University of California, Berkeley, CA 94720-1740, USA b University of Sao Paulo, Nucleus of Advanced Manufacturing, Sao Carlos, Brazil Received 27 January 2005; accepted 7 April 2005 Available online 13 June 2005 Abstract Current demands in high-technology industries such as semiconductor, optics, MEMS, etc. have predicated the need for Manufacturing processes that can fabricate increasingly smaller features reliably at very high tolerances. In situ monitoring systems that can be used to characterize, control, and improve the fabrication of these smaller features are therefore needed to meet increasing demands in Precision and quality. This paper discusses the unique requirements of monitoring of Precision Manufacturing processes, and the suitability of acoustic emission (AE) as a monitoring technique at the Precision scale. Details are then given on the use of AE sensor technology in the monitoring of Precision Manufacturing processes; grinding, chemical–mechanical planarization (CMP) and ultraPrecision diamond turning in particular. q 2005 Elsevier Ltd. All rights reserved. Keywords: Acoustic emission; Precision; Process monitoring 1. Introduction Current demands in high-technology industries such as semiconductor, optics, MEMS, etc. have predicated the need for Manufacturing processes that can fabricate increasingly smaller features reliably at very high toler- ances. This increasing demand for the ability to fabricate features at smaller length scales and at greater Precision can be represented in the Taniguchi curve (Fig. 1), which demonstrates that the smallest achievable accuracy (and, as a consequence, smallest reproducible feature) decreases as a function of time [1]. In situ monitoring systems that can be used to characterize, control, and improve the fabrication of these smaller features are therefore needed to meet increasing demands in Precision and quality. Sensor-based monitoring yields valuable information about the Manufacturing process that can serve the dual purpose of process control and quality monitoring, and will ultimately be the part of any fully automated Manufacturing environment. However, a high degree of confidence and reliability in characterizing * Corresponding author. Tel.: C1 510 642 0906; fax: C1 510 643 7492. E-mail addresses: cmov@sc.usp.br (C.M.O. Valente), dornfeld@me. berkeley.edu (D.A. Dornfeld). the Manufacturing process is required for any sensor to be utilized as a monitoring tool. As demonstrated in a previous review paper by Dornfeld et al. [2], acoustic emission (AE) has demonstrated a high degree of confidence in character- izing various phenomena related to material removal, particularly at the microscale, hence lending credence to its suitability for Precision Manufacturing process monitor- ing. This work serves to demonstrate sensitivity of AE at the three different Manufacturing regimes outlined in the Taniguchi curve; the normal/conventional, Precision, and ultraPrecision scales (Fig. 1). 2. Requirements for sensor technology at the Precision scale In material removal processes at the Precision scale, the undeformed chip thickness can be on the order of a few microns or less, and can approach the nanoscale in some cases. At these length scales, the surface, subsurface, and edge condition of machined features and the fundamental mechanism for chip formation are much more intimately affected by the material properties and microstructure of the workpiece material, such as ductile/brittle behavior, crystal- lographic orientation of the material at the tool/chip interface, and microtopographical features such as voids, secondary phases, and interstitial particulates [3,4]. 0890-6955/$ - see front matter q 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijmachtools.2005.04.001
David R Martinez - One of the best experts on this subject based on the ideXlab platform.
-
Vibration Control for Precision Manufacturing Using Piezoelectric Actuators
Journal of Intelligent Material Systems and Structures, 1996Co-Authors: David R Martinez, Terry D Hinnerichs, James M. RedmondAbstract:Piezoelectric actuators provide high frequency, force and stiffness capabilities along with reasonable stroke limits, all of which can be used to increase performance levels in Precision Manufacturing systems. This paper describes two examples of embedding piezoelectric actuators in structural components for vibration control. One example involves suppressing the self-excited chatter phenomenon in the metal cutting process of a milling machine and the other involves damping vibrations induced by rigid body stepping of a photolithography platen. Finite element modeling and analyses are essential for locating and sizing the actuators and permit further simulation studies of the response of the dynamic system. Experimental results are given for embedding piezoelectric actuators in a cantilevered bar configuration, which was used as a surrogate machine tool structure. These results are incorporated into a previously developed milling process simulation and the effect of the control on the cutting process stab...
-
Vibration control for Precision Manufacturing using piezoelectric actuators
1995Co-Authors: David R Martinez, Terry D Hinnerichs, James M. RedmondAbstract:Piezoelectric actuators provide high frequency, force, and stiffness capabilities along with reasonable Stroke limits, all of which can be used to increase performance levels in Precision Manufacturing systems. This paper describes two examples of embedding piezoelectric actuators in structural components for vibration control. One example involves suppressing the self excited chatter phenomenon in the metal cutting process of a milling machine and the other involves damping vibrations induced by rigid body stepping of a photolithography platen. Finite element modeling and analyses are essential for locating and sizing the actuators and permit further simulation studies of the response of the dynamic system. Experimental results are given for embedding piezoelectric actuators in a cantilevered bar configuration, which was used as a surrogate machine tool structure. These results are incorporated into a previously developed milling process simulation and the effect of the control on the cutting process stability diagram is quantified. Experimental results are also given for embedding three piezoelectric actuators in a surrogate photolithography platen to suppress vibrations. These results demonstrate the potential benefit that can be realized by applying advances from the field of adaptive structures to problems in Precision Manufacturing.
-
Vibration control for Precision Manufacturing at Sandia National Laboratories
Smart Structures and Materials 1995: Industrial and Commercial Applications of Smart Structures Technologies, 1995Co-Authors: Terry D Hinnerichs, David R MartinezAbstract:Sandia National Laboratories performs R and D in structural dynamics and vibration suppression for Precision applications in weapon systems, space, underwater, transportation and civil structures. Over the last decade these efforts have expanded into the areas of active vibration control and ``smart`` structures and material systems. In addition, Sandia has focused major resources towards technology to support weapon product development and agile Manufacturing capability for defense and industrial applications. This paper will briefly describe the structural dynamics modeling and verification process currently in place at Sandia that supports vibration control and some specific applications of these techniques to Manufacturing in the areas of lithography, machine tools and flexible robotics.
-
Vibration control for Precision Manufacturing at Sandia Natl. Lab.
Proceedings of SPIE - The International Society for Optical Engineering, 1995Co-Authors: Terry D Hinnerichs, David R MartinezAbstract:Sandia National Laboratories performs R&D in structural dynamics and vibration suppression of Precision applications in weapon systems, space, underwater, transportation and civil structures. Over the last decade these efforts have expanded into the areas of active vibration control and 'smart' structures and material systems, In addition, major resources have been focused towards technology to support weapon product development and agile Manufacturing capability for defense and industrial applications. This paper will briefly describe the structural dynamics modeling and verification process that supports vibration control and some specific applications of these techniques to Manufacturing in the areas of lithography, machine tools and flexible robotics.
Terry D Hinnerichs - One of the best experts on this subject based on the ideXlab platform.
-
Vibration Control for Precision Manufacturing Using Piezoelectric Actuators
Journal of Intelligent Material Systems and Structures, 1996Co-Authors: David R Martinez, Terry D Hinnerichs, James M. RedmondAbstract:Piezoelectric actuators provide high frequency, force and stiffness capabilities along with reasonable stroke limits, all of which can be used to increase performance levels in Precision Manufacturing systems. This paper describes two examples of embedding piezoelectric actuators in structural components for vibration control. One example involves suppressing the self-excited chatter phenomenon in the metal cutting process of a milling machine and the other involves damping vibrations induced by rigid body stepping of a photolithography platen. Finite element modeling and analyses are essential for locating and sizing the actuators and permit further simulation studies of the response of the dynamic system. Experimental results are given for embedding piezoelectric actuators in a cantilevered bar configuration, which was used as a surrogate machine tool structure. These results are incorporated into a previously developed milling process simulation and the effect of the control on the cutting process stab...
-
Vibration control for Precision Manufacturing using piezoelectric actuators
1995Co-Authors: David R Martinez, Terry D Hinnerichs, James M. RedmondAbstract:Piezoelectric actuators provide high frequency, force, and stiffness capabilities along with reasonable Stroke limits, all of which can be used to increase performance levels in Precision Manufacturing systems. This paper describes two examples of embedding piezoelectric actuators in structural components for vibration control. One example involves suppressing the self excited chatter phenomenon in the metal cutting process of a milling machine and the other involves damping vibrations induced by rigid body stepping of a photolithography platen. Finite element modeling and analyses are essential for locating and sizing the actuators and permit further simulation studies of the response of the dynamic system. Experimental results are given for embedding piezoelectric actuators in a cantilevered bar configuration, which was used as a surrogate machine tool structure. These results are incorporated into a previously developed milling process simulation and the effect of the control on the cutting process stability diagram is quantified. Experimental results are also given for embedding three piezoelectric actuators in a surrogate photolithography platen to suppress vibrations. These results demonstrate the potential benefit that can be realized by applying advances from the field of adaptive structures to problems in Precision Manufacturing.
-
Vibration control for Precision Manufacturing at Sandia National Laboratories
Smart Structures and Materials 1995: Industrial and Commercial Applications of Smart Structures Technologies, 1995Co-Authors: Terry D Hinnerichs, David R MartinezAbstract:Sandia National Laboratories performs R and D in structural dynamics and vibration suppression for Precision applications in weapon systems, space, underwater, transportation and civil structures. Over the last decade these efforts have expanded into the areas of active vibration control and ``smart`` structures and material systems. In addition, Sandia has focused major resources towards technology to support weapon product development and agile Manufacturing capability for defense and industrial applications. This paper will briefly describe the structural dynamics modeling and verification process currently in place at Sandia that supports vibration control and some specific applications of these techniques to Manufacturing in the areas of lithography, machine tools and flexible robotics.
-
Vibration control for Precision Manufacturing at Sandia Natl. Lab.
Proceedings of SPIE - The International Society for Optical Engineering, 1995Co-Authors: Terry D Hinnerichs, David R MartinezAbstract:Sandia National Laboratories performs R&D in structural dynamics and vibration suppression of Precision applications in weapon systems, space, underwater, transportation and civil structures. Over the last decade these efforts have expanded into the areas of active vibration control and 'smart' structures and material systems, In addition, major resources have been focused towards technology to support weapon product development and agile Manufacturing capability for defense and industrial applications. This paper will briefly describe the structural dynamics modeling and verification process that supports vibration control and some specific applications of these techniques to Manufacturing in the areas of lithography, machine tools and flexible robotics.
I Hwang - One of the best experts on this subject based on the ideXlab platform.
-
Precision Manufacturing Process Monitoring with Acoustic Emission
Laboratory for Manufacturing and Sustainability, 2007Co-Authors: I Hwang, C M O ValenteAbstract:Demands in high-technology industries such as semiconductor, optics, MEMS, etc., have predicated the need for Manufacturing processes that can fabricate increasingly smaller features reliably at very high tolerances. In-situ monitoring systems that can be used to characterize, control, and improve the fabrication of these smaller features are therefore needed to meet increasing demands in Precision and quality. This paper discusses the unique requirements of monitoring of Precision Manufacturing processes, and the suitability of acoustic emission (AE) as a monitoring technique at the Precision scale. Details are then given on the use of AE sensor technology in the monitoring of Precision Manufacturing processes; grinding, chemical mechanical planarization (CMP) and ultraPrecision diamond turning in particular.
-
Precision Manufacturing process monitoring with acoustic emission
International Journal of Machine Tools & Manufacture, 2006Co-Authors: I Hwang, C M O Valente, Joao Fernando Gomes De Oliveira, David DornfeldAbstract:Abstract Current demands in high-technology industries such as semiconductor, optics, MEMS, etc. have predicated the need for Manufacturing processes that can fabricate increasingly smaller features reliably at very high tolerances. In situ monitoring systems that can be used to characterize, control, and improve the fabrication of these smaller features are therefore needed to meet increasing demands in Precision and quality. This paper discusses the unique requirements of monitoring of Precision Manufacturing processes, and the suitability of acoustic emission (AE) as a monitoring technique at the Precision scale. Details are then given on the use of AE sensor technology in the monitoring of Precision Manufacturing processes; grinding, chemical–mechanical planarization (CMP) and ultraPrecision diamond turning in particular.
-
Precision Manufacturing Process Monitoring with Acoustic Emission - eScholarship
2006Co-Authors: I Hwang, C M O Valente, J. F.g. Oliviera, David DornfeldAbstract:International Journal of Machine Tools & Manufacture 46 (2006) 176–188 www.elsevier.com/locate/ijmactool Precision Manufacturing process monitoring with acoustic emission D.E. Lee a , I. Hwang a , C.M.O. Valente b , J.F.G. Oliveira b , D.A. Dornfeld a, * a Laboratory for Manufacturing Automation, Department of Mechanical Engineering, University of California, Berkeley, CA 94720-1740, USA b University of Sao Paulo, Nucleus of Advanced Manufacturing, Sao Carlos, Brazil Received 27 January 2005; accepted 7 April 2005 Available online 13 June 2005 Abstract Current demands in high-technology industries such as semiconductor, optics, MEMS, etc. have predicated the need for Manufacturing processes that can fabricate increasingly smaller features reliably at very high tolerances. In situ monitoring systems that can be used to characterize, control, and improve the fabrication of these smaller features are therefore needed to meet increasing demands in Precision and quality. This paper discusses the unique requirements of monitoring of Precision Manufacturing processes, and the suitability of acoustic emission (AE) as a monitoring technique at the Precision scale. Details are then given on the use of AE sensor technology in the monitoring of Precision Manufacturing processes; grinding, chemical–mechanical planarization (CMP) and ultraPrecision diamond turning in particular. q 2005 Elsevier Ltd. All rights reserved. Keywords: Acoustic emission; Precision; Process monitoring 1. Introduction Current demands in high-technology industries such as semiconductor, optics, MEMS, etc. have predicated the need for Manufacturing processes that can fabricate increasingly smaller features reliably at very high toler- ances. This increasing demand for the ability to fabricate features at smaller length scales and at greater Precision can be represented in the Taniguchi curve (Fig. 1), which demonstrates that the smallest achievable accuracy (and, as a consequence, smallest reproducible feature) decreases as a function of time [1]. In situ monitoring systems that can be used to characterize, control, and improve the fabrication of these smaller features are therefore needed to meet increasing demands in Precision and quality. Sensor-based monitoring yields valuable information about the Manufacturing process that can serve the dual purpose of process control and quality monitoring, and will ultimately be the part of any fully automated Manufacturing environment. However, a high degree of confidence and reliability in characterizing * Corresponding author. Tel.: C1 510 642 0906; fax: C1 510 643 7492. E-mail addresses: cmov@sc.usp.br (C.M.O. Valente), dornfeld@me. berkeley.edu (D.A. Dornfeld). the Manufacturing process is required for any sensor to be utilized as a monitoring tool. As demonstrated in a previous review paper by Dornfeld et al. [2], acoustic emission (AE) has demonstrated a high degree of confidence in character- izing various phenomena related to material removal, particularly at the microscale, hence lending credence to its suitability for Precision Manufacturing process monitor- ing. This work serves to demonstrate sensitivity of AE at the three different Manufacturing regimes outlined in the Taniguchi curve; the normal/conventional, Precision, and ultraPrecision scales (Fig. 1). 2. Requirements for sensor technology at the Precision scale In material removal processes at the Precision scale, the undeformed chip thickness can be on the order of a few microns or less, and can approach the nanoscale in some cases. At these length scales, the surface, subsurface, and edge condition of machined features and the fundamental mechanism for chip formation are much more intimately affected by the material properties and microstructure of the workpiece material, such as ductile/brittle behavior, crystal- lographic orientation of the material at the tool/chip interface, and microtopographical features such as voids, secondary phases, and interstitial particulates [3,4]. 0890-6955/$ - see front matter q 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijmachtools.2005.04.001
