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David Dornfeld - One of the best experts on this subject based on the ideXlab platform.
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Micromachining and Burr Formation for Precision Components
2007Co-Authors: Jeffrey Hartnett, Sangkee Min, David DornfeldAbstract:A Micromachining and Burr Formation for Precision Mechanical Components Jeffrey Hartnett, Sangkee Min, David Dornfeld Laboratory for Manufacturing and Sustainability, Department of Mechanical Engineering University of California at Berkeley Berkeley, California USA 94720-1740 Abstract An understanding of Burr Formation and edge defects is critical to efficient production of machined features in precision components. Analytical models of Burr Formation and edge effects including the tool/workpiece interaction and material influences are necessary for building databases describing cutting conditions for optimal edge quality, and design rules for Burr and edge defect prevention. This paper reviews recent research work done on the fundamentals of Burr Formation in micro-milling of microfluidic devices using the Mori Seiki NV15OO DCG Vertical Milling Machine as part of the MTTRF machine loan program at the University of California at Berkeley. Specific applications of micromachining and Burr Formation test results for of micro-scale components are presented and discussed. Keywords: Micromachining, Burrs, experimental data bases 1 INTRODUCTION Micro—machining as a manufacturing technique represents a continued trend towards miniaturization across all areas of manufacturing. However, there still remain many technical hurdles prior to widespread use of micro- machining, and specifically micro-milling, industry-wide. This is mainly due to the fact that as feature sizes continue to decrease, effects considered to have little or no influence at larger scales become dominant factors with strong influences on part accuracy, surface generation, and integrity of components [1]. These factors need to be addressed when developing process parameters to ensure machined parts meet desired form and tolerance specifications. it has been the goal of the Laboratory for Manufacturing and Sustainability over the years to conduct research on the fundamental aspects of Burr characterization, minimization, prevention, and removal. it is a goal to continue to expand this research to machining at the micro-scale. As these issues are addressed the applications where micro-milling can be utilized as a manufacturing technique will increase. It is increasingly common to see milling used for meso-scale electronics, plastic injection molds, and devices such as micro-turbines and pumps. An interesting application for micro-milling is the area of micro-fluidic devices. These are miniaturized devices that are used to manipulate micro- and nano—liter volumes in an effort to understand cellular mechanisms. The devices are used for live cell experimentation to better understand inter- and intra-cellular interactions [2]. Typical applications of these devices are: o Drug screening and testing o Biological and chemical sensing - Genetic analysis Figure 1 displays a sample micro-fluidic device known as a micro-mixer. Efficient mixing of reagents is desirable for applications where fast diagnosis results are needed [3]. The size of the features makes micro-milling a viable option for manufacture of the device. Micro-fluidic devices typically make use of more traditional microfabrlcation techniques used to pattern integrated circuits on silicon wafers [2]. The device illustrated in Figure 1 used a typical method of device fabrication where © 2007 The Proceedings of OMNI-CNC 2007 Annual Meeting SU-8 and OmniCoat photoresist were spin coated on a nickel disk. The disks were then electroplated with nickel before removing the photoresist. Finally the nickel disks were used in a plastic injection molding process to make a polymer mold. There are many advantages to traditional microfabrlcation techniques such as lithography, including being able to attain microscopic feature sizes, and high fidelity replication of desired features. However these traditional methods are limited in the complexity as they can only create features in 2.5-dimensions. Additionally they typically require longer lead times for manufacture. For example the electroplating process described above took in excess of 6 hours. Otltict HOV as ff’ , ifiefitiptzn Qiiitim Zfiiflgaitl .32‘ W“ Figure 1: Micro-mixer micro-fluidic device [3]. 231
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Micromachining and Burr Formation for Precision Mechanical Components
2007Co-Authors: Jeffrey Hartnett, Sangkee Min, David DornfeldAbstract:Micromachining and Burr Formation for Precision Mechanical Components J. Hartnett1, S. Min1, D. Dornfe|d1 Laboratory for Manufacturing and Automation, Department of Mechanical Engineering University of California Berkeley, California 94720-1 740 Abstract An understanding of Burr Formation and edge defects is critical to efficient production of machined features in precision components. Analytical models of Burr Formation and edge effects including the tool/workpiece interaction and material influences are necessary for building databases describing cutting conditions for optimal edge quality, and design rules for Burr and edge defect prevention. This paper reviews recent research work done on the fundamentals of Burr Formation in micro-milling of microfluidic devices using the Mori Seiki NV150O DCG Vertical Milling Machine as part of the MTTRF machine loan program at the University of California at Berkeley. Specific applications of micromachining and Burr Formation test results for of micro-scale components are presented and discussed. Keywords: Micromachining, Burrs, experimental data bases 1 INTRODUCTION Micro-machining as a manufacturing technique represents a continued trend towards miniaturization across all areas of manufacturing. However, there still remain many technical hurdles prior to widespread use of micro-machining, and specifically micro-milling, industry- wide. This is mainly due to the fact that as feature sizes continue to decrease, effects considered to have little or no influence at larger scales become dominant factors with strong influences on part accuracy, surface generation, and integrity of components [1]. These factors need to be addressed when developing process parameters to ensure machined parts meet desired form and tolerance specifications. It has been the goal of the Laboratory for Manufacturing and Sustainability over the years to conduct research on the fundamental aspects of Burr characterization, minimization, prevention, and removal. it is a goal to continue to expand this research to machining at the micro-scale. As these issues are addressed the applications where micro-milling can be utilized as a manufacturing technique will increase. it is increasingly common to see milling used for meso-scale electronics, plastic injection molds, and devices such as micro-turbines and pumps. An interesting application for micro-milling is the area of micro-fluidic devices. These are miniaturized devices that are used to manipulate micro- and nano-liter volumes in an effort to understand cellular mechanisms. The devices are used for live cell experimentation to better understand inter- and intra-cellular interactions [2]. Typical applications of these devices are: - Drug screening and testing - Biological and chemical sensing - Genetic analysis Figure 1 displays a sample micro-fluidic device known as a micro-mixer. Efficient mixing of reagents is desirable for applications where fast diagnosis results are needed [3]. The size of the features makes micro-milling a viable option for manufacture of the device. Micro-fluidic devices typically make use of more traditional microfabrication techniques used to pattern integrated circuits on silicon wafers [2]. The device illustrated in Figure 1 used a typical method of device fabrication where SU-8 and OmniCoat photoresist were spin coated on a nickel disk. The disks were then electroplated with nickel before removing the photoresist. Finally the nickel disks were used in a plastic injection molding process to make a polymer mold. There are many advantages to traditional microfabrication techniques such as lithography, including being able to attain microscopic feature sizes, and high fidelity replication of desired features. However these traditional methods are limited in the complexity as they can only create features in 2.5-dimensions. Additionally they typically require longer lead times for manufacture. For example the electroplating process described above took in excess of 6 hours. ()iit.Eet tlou Figure 1: Micro-mixer micro-fluidic device [3]. Micro-milling may be a viable alternative to these processes due to the ability to manufacture true 3-
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Micro-Burr Formation and minimization through process control
Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology, 2005Co-Authors: David DornfeldAbstract:Abstract This paper presents an investigation on micro-Burr Formation in machining. Micro-cutting is compared with conventional cutting in terms of cutting process characteristic and cutting conditions. In this paper, tungsten–carbide micro-mills were used to cut holes (in a drilling-like process) to investigate top Burr Formation. The size and type of Burr created in stainless steel 304 are studied as a function of machining variables, which are feed, cutting speed and cutting edge radius, to help illuminate the micro-Burr Formation mechanisms. A series of experiments was conducted to study tool life as a function of cutting conditions. Tool life, here, is defined as the number of holes created before a significant increase in Burr height. Based on experimental results, contour charts for predicting Burr Formation as well as tool life are developed to minimize Burr Formation and to improve tool life. The model, which includes the effect of feed, cutting speed, and the interaction between the two, predicted the Burr height and tool life values with an accuracy of about ±15%.
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Strategies for Preventing and Minimizing Burr Formation - eScholarship
2004Co-Authors: David DornfeldAbstract:The past years have seen emphasis on increasing the quality of machined workpieces while at the same time reducing the cost per piece. Accompanying this is the decreasing size and increasing complexity of workpieces. This has put continual pressure on improvements in the machining process in terms of new processes, new tooling and tool materials, and new machine tools. This often falls under the terminology of High Performance Cutting (HPC) — the theme of this conference. A recent CIRP keynote /1/ outlined and explained some of these drivers for enhancement in machining technology. Fundamental to this continual improvement is understanding edge finishing of machined components, specially Burrs. DeBurring, like inspection, is a non-productive operation and, as such, should be eliminated or minimized to the greatest extent possible. nderstanding of the fundamentals of Burr Formation leads us to procedures for preventing or, at least, minimizing, Burr Formation. This depends on analytical models of Burr Formation, studies of tool/workpiece interaction for understanding the creation of Burrs and, specially, the material influence, data bases describing cutting conditions for optimal edge quality, and design rules for Burr prevention as well as standard terminology for describing edge features and Burrs. Ultimately, engineering software tools must be available so that design and manufacturing engineers can use this knowledge interactively in their tasks to yield a mechanical part whose design and production is optimized for Burr prevention along with the other critical specifications. This paper reviews recent work done in all these areas with an emphasis on research at the University of California at Berkeley.
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Strategies for Preventing and Minimizing Burr Formation
2004Co-Authors: David DornfeldAbstract:Author(s): Dornfeld, David | Abstract: The past years have seen emphasis on increasing the quality of machined workpieces while at the same time reducing the cost per piece. Accompanying this is the decreasing size and increasing complexity of workpieces. This has put continual pressure on improvements in the machining process in terms of new processes, new tooling and tool materials, and new machine tools. This often falls under the terminology of High Performance Cutting (HPC) — the theme of this conference. A recent CIRP keynote /1/ outlined and explained some of these drivers for enhancement in machining technology. Fundamental to this continual improvement is understanding edge finishing of machined components, specially Burrs. DeBurring, like inspection, is a non-productive operation and, as such, should be eliminated or minimized to the greatest extent possible. nderstanding of the fundamentals of Burr Formation leads us to procedures for preventing or, at least, minimizing, Burr Formation. This depends on analytical models of Burr Formation, studies of tool/workpiece interaction for understanding the creation of Burrs and, specially, the material influence, data bases describing cutting conditions for optimal edge quality, and design rules for Burr prevention as well as standard terminology for describing edge features and Burrs. Ultimately, engineering software tools must be available so that design and manufacturing engineers can use this knowledge interactively in their tasks to yield a mechanical part whose design and production is optimized for Burr prevention along with the other critical specifications. This paper reviews recent work done in all these areas with an emphasis on research at the University of California at Berkeley.
Deng Wenjun - One of the best experts on this subject based on the ideXlab platform.
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Analytical model and experimental verification of Poisson Burr Formation in ductile metal machining
Journal of Materials Processing Technology, 2021Co-Authors: Xueqin Pang, Jiayang Zhang, Yuning Zeng, Deng WenjunAbstract:Abstract Previous investigations on the theoretical model to predict Burr dimensions have normally been confined to a single geometric model, and the findings that have been proposed rarely take into account the influence of multi-physics factors on Burr Formation in the complex machining process. This paper proposes an analytical model to reveal subsurface plastic deFormation behavior in machining of ductile material. This model is developed based on coupled thermo-mechanical factors. More importantly, the material property and tool edge arc are taken into consideration. According to the proposed model, the two approaches are presented to predict Poisson Burr height and root thickness. Moreover, the material flow and Burr Formation mechanism are further investigated at great length. The effects of machining parameters and material properties on Burr Formation are analyzed and discussed in terms of plastic deFormation behavior. The results show that this proposed model can describe Burr morphology and predict Burr size accurately. Poisson Burr generation has a great sensitivity to machining parameters, as well as material property, and the transition of Burr morphology is caused by severe lateral material flow owing to material softening effect at high temperature. There is the synchronous interaction between machining parameters and material property influencing Burr Formation. As a result, this study provides a valuable theoretical reference and basis for the deBurring energy minimization, high surface quality, and machining parameters optimization.
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Investigation on the modelling and characterization of top edge Burr Formation in slotting finned tube
The International Journal of Advanced Manufacturing Technology, 2020Co-Authors: Xueqin Pang, Xiao Liu, Jiayang Zhang, Deng WenjunAbstract:In this study, a three-dimensional finite element model is utilized to analyse the top edge Burr Formation in orthogonal slotting copper finned tubes. To describe the top edge Burr generation, a conceptual model is developed to explain the material shear failure. The normalized Cockroft-Latham criterion is employed for a general understanding of the plastic behaviour and Burr Formation, and the critical damage value is obtained to qualify the Burr geometries by tensile tests. Based on material side flow and the progressive deFormation behaviour, the characteristics and mechanism of top edge Burr Formation are further investigated. The results show that the top edge Burr is formed by a combination of material tear and sideward flow. The top edge Burr Formation process can generally be divided into three phases: the initiation of the deFormation bulge, the development of the deFormation bulge, and tear Formation. The characteristics of the top edge Burr also consist of three parts: basal deFormation area, tensile area, and top tear area. The three parts of the Burr characteristics correspond to the three phases of the Burr Formation process. Additionally, the influences of rake face, feed rate, and cutting speed on the Burr size are studied based on a quantitative method. The study provides a basis for the minimization of top edge Burr Formation and optimization of machining parameters.
Uwe Heisel - One of the best experts on this subject based on the ideXlab platform.
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Burr Formation in short hole drilling by ultrasonic assistance
Production Engineering, 2014Co-Authors: Uwe Heisel, Thomas Stehle, Michael Schaal, Rocco EisselerAbstract:Both in the industry and the service sector, the three aspects of time, costs and quality are among the most important characteristics in the manufacturing. This implies time as well as the costs incurred should be minimalized while preserving the high quality of a product. On top of that, the quality should be high as well. Burr Formation has a negative influence on all of these three aspects. In most cases, formed Burrs require additional remachining in most cases, leading to higher costs as well. In addition, the quality of the component is also impaired by Burr Formation.This paper examines to what extent short hole drilling by ultrasonic assistance can reduce Burr Formation. In order to assess the influence of ultrasound, the vibration amplitude is measured with and without load, depending on the excitation power. Based on these findings, the tests are carried out measuring exit Burrs and evaluating them. Results show that the smallest Burr values were measured without excitation, yet Burr Formation tends to decrease again with growing power.
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Influence of Minimum Quantity Lubrication on Burr Formation in Milling
Burrs - Analysis Control and Removal, 2009Co-Authors: Uwe Heisel, Michael Schaal, G. WolfAbstract:Workpieces that are manufactured by machining processes often have to be deBurred with considerable effort. This rework involves time and costs. The avoidance or at least minimisation of Burr Formation offers potential for a more economical production. Another possibility to save costs is to use minimum quantity lubrication. The investigation into the Burr Formation in milling with minimum quantity lubrication combines these two approaches. The test results presented in this paper show the influence both procedures have on Burr Formation.
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Burr Formation in short hole drilling with minimum quantity lubrication
Production Engineering, 2009Co-Authors: Uwe Heisel, Michael SchaalAbstract:Machining with minimum quantity lubrication (MQL) is state of the art. Previous investigations were, however, concerned with tool optimisation and the surface quality of workpieces as well as coating technology. By now the same or partly better machining results than in conventional cutting with flood lubrication can be achieved due to adjusted tool geometries, workpiece materials and coatings. Tests about Burr Formation in short hole drilling exist for dry cutting or the machining with emulsion. This paper expands these results to the Burr Formation in machining with MQL.
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Burr Formation in milling with minimum quantity lubrication
Production Engineering, 2009Co-Authors: Uwe Heisel, Michael Schaal, G. WolfAbstract:In milling, Burrs are formed on entry and exit edges of the workpiece to be machined like in all material removal processes. In the subsequent production these Burrs have to be removed. Understanding the influencing factors and Burr Formation mechanisms can help to avoid or reduce Burrs. Another possibility for saving costs is to reduce the process materials, for example, cutting fluids. This can be realised by using minimum quantity lubrication or dry machining. The investigations show which influence both methods have on Burr Formation.
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Burr Formation in intersecting holes
Production Engineering, 2008Co-Authors: Uwe Heisel, Michael SchaalAbstract:Regarding intersecting holes, the edges of cut are often difficult to access, as they are located inside the components. Hence it requires a lot of time and money to deBurr them. In addition, Burrs which come off in the later operation can lead to resultant damages. Examinations of intersecting holes showed that the effective exit surface angle, the angle between drill wall and exit surface, is crucial for Burr Formation. Based on the Burr calculation for exit surfaces perpendicular to the drill axis, a method of calculation was developed out of the experimental results. By means of this calculation method the Burr value g can be predicted for the short hole drilling of intersecting holes.
Michael Schaal - One of the best experts on this subject based on the ideXlab platform.
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Burr Formation in short hole drilling by ultrasonic assistance
Production Engineering, 2014Co-Authors: Uwe Heisel, Thomas Stehle, Michael Schaal, Rocco EisselerAbstract:Both in the industry and the service sector, the three aspects of time, costs and quality are among the most important characteristics in the manufacturing. This implies time as well as the costs incurred should be minimalized while preserving the high quality of a product. On top of that, the quality should be high as well. Burr Formation has a negative influence on all of these three aspects. In most cases, formed Burrs require additional remachining in most cases, leading to higher costs as well. In addition, the quality of the component is also impaired by Burr Formation.This paper examines to what extent short hole drilling by ultrasonic assistance can reduce Burr Formation. In order to assess the influence of ultrasound, the vibration amplitude is measured with and without load, depending on the excitation power. Based on these findings, the tests are carried out measuring exit Burrs and evaluating them. Results show that the smallest Burr values were measured without excitation, yet Burr Formation tends to decrease again with growing power.
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Influence of Minimum Quantity Lubrication on Burr Formation in Milling
Burrs - Analysis Control and Removal, 2009Co-Authors: Uwe Heisel, Michael Schaal, G. WolfAbstract:Workpieces that are manufactured by machining processes often have to be deBurred with considerable effort. This rework involves time and costs. The avoidance or at least minimisation of Burr Formation offers potential for a more economical production. Another possibility to save costs is to use minimum quantity lubrication. The investigation into the Burr Formation in milling with minimum quantity lubrication combines these two approaches. The test results presented in this paper show the influence both procedures have on Burr Formation.
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Burr Formation in short hole drilling with minimum quantity lubrication
Production Engineering, 2009Co-Authors: Uwe Heisel, Michael SchaalAbstract:Machining with minimum quantity lubrication (MQL) is state of the art. Previous investigations were, however, concerned with tool optimisation and the surface quality of workpieces as well as coating technology. By now the same or partly better machining results than in conventional cutting with flood lubrication can be achieved due to adjusted tool geometries, workpiece materials and coatings. Tests about Burr Formation in short hole drilling exist for dry cutting or the machining with emulsion. This paper expands these results to the Burr Formation in machining with MQL.
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Burr Formation in milling with minimum quantity lubrication
Production Engineering, 2009Co-Authors: Uwe Heisel, Michael Schaal, G. WolfAbstract:In milling, Burrs are formed on entry and exit edges of the workpiece to be machined like in all material removal processes. In the subsequent production these Burrs have to be removed. Understanding the influencing factors and Burr Formation mechanisms can help to avoid or reduce Burrs. Another possibility for saving costs is to reduce the process materials, for example, cutting fluids. This can be realised by using minimum quantity lubrication or dry machining. The investigations show which influence both methods have on Burr Formation.
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Burr Formation in intersecting holes
Production Engineering, 2008Co-Authors: Uwe Heisel, Michael SchaalAbstract:Regarding intersecting holes, the edges of cut are often difficult to access, as they are located inside the components. Hence it requires a lot of time and money to deBurr them. In addition, Burrs which come off in the later operation can lead to resultant damages. Examinations of intersecting holes showed that the effective exit surface angle, the angle between drill wall and exit surface, is crucial for Burr Formation. Based on the Burr calculation for exit surfaces perpendicular to the drill axis, a method of calculation was developed out of the experimental results. By means of this calculation method the Burr value g can be predicted for the short hole drilling of intersecting holes.
Xueqin Pang - One of the best experts on this subject based on the ideXlab platform.
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Analytical model and experimental verification of Poisson Burr Formation in ductile metal machining
Journal of Materials Processing Technology, 2021Co-Authors: Xueqin Pang, Jiayang Zhang, Yuning Zeng, Deng WenjunAbstract:Abstract Previous investigations on the theoretical model to predict Burr dimensions have normally been confined to a single geometric model, and the findings that have been proposed rarely take into account the influence of multi-physics factors on Burr Formation in the complex machining process. This paper proposes an analytical model to reveal subsurface plastic deFormation behavior in machining of ductile material. This model is developed based on coupled thermo-mechanical factors. More importantly, the material property and tool edge arc are taken into consideration. According to the proposed model, the two approaches are presented to predict Poisson Burr height and root thickness. Moreover, the material flow and Burr Formation mechanism are further investigated at great length. The effects of machining parameters and material properties on Burr Formation are analyzed and discussed in terms of plastic deFormation behavior. The results show that this proposed model can describe Burr morphology and predict Burr size accurately. Poisson Burr generation has a great sensitivity to machining parameters, as well as material property, and the transition of Burr morphology is caused by severe lateral material flow owing to material softening effect at high temperature. There is the synchronous interaction between machining parameters and material property influencing Burr Formation. As a result, this study provides a valuable theoretical reference and basis for the deBurring energy minimization, high surface quality, and machining parameters optimization.
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Investigation on the modelling and characterization of top edge Burr Formation in slotting finned tube
The International Journal of Advanced Manufacturing Technology, 2020Co-Authors: Xueqin Pang, Xiao Liu, Jiayang Zhang, Deng WenjunAbstract:In this study, a three-dimensional finite element model is utilized to analyse the top edge Burr Formation in orthogonal slotting copper finned tubes. To describe the top edge Burr generation, a conceptual model is developed to explain the material shear failure. The normalized Cockroft-Latham criterion is employed for a general understanding of the plastic behaviour and Burr Formation, and the critical damage value is obtained to qualify the Burr geometries by tensile tests. Based on material side flow and the progressive deFormation behaviour, the characteristics and mechanism of top edge Burr Formation are further investigated. The results show that the top edge Burr is formed by a combination of material tear and sideward flow. The top edge Burr Formation process can generally be divided into three phases: the initiation of the deFormation bulge, the development of the deFormation bulge, and tear Formation. The characteristics of the top edge Burr also consist of three parts: basal deFormation area, tensile area, and top tear area. The three parts of the Burr characteristics correspond to the three phases of the Burr Formation process. Additionally, the influences of rake face, feed rate, and cutting speed on the Burr size are studied based on a quantitative method. The study provides a basis for the minimization of top edge Burr Formation and optimization of machining parameters.
