Experimental and Numerical Investigation of Laser Assisted Milling of Silicon Nitride Ceramics PDF Download
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Author: Budong Yang
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
This study experimentally and numerically investigates laser assisted milling (LAMill) of silicon nitride ceramics. Experiments are conducted to study the machinability of Si3N4 under LAMill. The effects of temperature on cutting forces, tool wear, surface integrity, edge chipping and material removal mechanisms are investigated. It is shown that when temperature increases, cutting force and tool wear are significantly decreased, surface integrity is improved, chip size is increased and material removal demonstrates more plastic characteristics. The mechanisms of edge chipping at elevated temperature are investigated theoretically and experimentally. When temperature is above the softening point and below the brittle/ductile transition temperature, the mechanism is mainly through softening. When temperature is above the brittle/ductile transition temperature, toughening mechanism contributes significantly to the reduced edge chipping. The coupled effect of softening and toughening mechanisms shows that temperature range between 1200 to 1400°C has the most significant effect to reduce edge chipping. Distinct element method (DEM) is applied to simulate the micro-mechanical behavior of Si3N4. First, quantitative relationships between particle level parameters and macro-properties of the bonded particle specimens are obtained, which builds a foundation for simulation of Si3N4. Then, extensive DEM simulations are conducted to model the material removal of machining Si3N4. The simulation results demonstrate that DEM can reproduce the conceptual material removal model summarized from experimental observations, including the initiation and propagation of cracks, chip formation process and material removal mechanisms. It is shown that material removal is mainly realized by propagation of lateral cracks in machining of silicon nitride. At the elevated temperature under laser assisted machining, lateral cracks are easier to propagate to form larger machined chips, there are fewer and smaller median cracks therefore less surface/subsurface damage, and crushing-type material removal is reduced. The material removal at elevated temperature demonstrates more plastic characteristics. The numerical results agree very well with experimental observations. It shows that DEM is a promising method to model the micro-mechanical process of machining Si3N4.
Author: Budong Yang
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
This study experimentally and numerically investigates laser assisted milling (LAMill) of silicon nitride ceramics. Experiments are conducted to study the machinability of Si3N4 under LAMill. The effects of temperature on cutting forces, tool wear, surface integrity, edge chipping and material removal mechanisms are investigated. It is shown that when temperature increases, cutting force and tool wear are significantly decreased, surface integrity is improved, chip size is increased and material removal demonstrates more plastic characteristics. The mechanisms of edge chipping at elevated temperature are investigated theoretically and experimentally. When temperature is above the softening point and below the brittle/ductile transition temperature, the mechanism is mainly through softening. When temperature is above the brittle/ductile transition temperature, toughening mechanism contributes significantly to the reduced edge chipping. The coupled effect of softening and toughening mechanisms shows that temperature range between 1200 to 1400°C has the most significant effect to reduce edge chipping. Distinct element method (DEM) is applied to simulate the micro-mechanical behavior of Si3N4. First, quantitative relationships between particle level parameters and macro-properties of the bonded particle specimens are obtained, which builds a foundation for simulation of Si3N4. Then, extensive DEM simulations are conducted to model the material removal of machining Si3N4. The simulation results demonstrate that DEM can reproduce the conceptual material removal model summarized from experimental observations, including the initiation and propagation of cracks, chip formation process and material removal mechanisms. It is shown that material removal is mainly realized by propagation of lateral cracks in machining of silicon nitride. At the elevated temperature under laser assisted machining, lateral cracks are easier to propagate to form larger machined chips, there are fewer and smaller median cracks therefore less surface/subsurface damage, and crushing-type material removal is reduced. The material removal at elevated temperature demonstrates more plastic characteristics. The numerical results agree very well with experimental observations. It shows that DEM is a promising method to model the micro-mechanical process of machining Si3N4.
Author: Xinwei Shen
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Laser-assisted machining (LAM) is a promising non-conventional machining technique for advanced ceramics. However, the fundamental machining mechanism which governs the LAM process is not well understood so far. Hence, the main objective of this study is to explore the machining mechanism and provide guidance for future LAM operations. In this study, laser-assisted milling (LAMill) of silicon nitride ceramics is focused. Experimental experience reveals that workpiece temperature in LAM of silicon nitride ceramics determines the surface quality of the machined workpiece. Thus, in order to know the thermal features of the workpiece in LAM, the laser-silicon nitride interaction mechanism is investigated via heating experiments. The trends of temperature affected by the key parameters (laser power, laser beam diameter, feed rate, and preheat time) are obtained through a parametric study. Experimental results show that high operating temperature leads to low cutting force, good surface finish, small edge chipping, and low residual stress. The temperature range for brittle-to-ductile transition should be avoided due to the rapid increase of fracture toughness. In order to know the temperature distribution at the cutting zone in the workpiece, a transient three-dimensional thermal model is developed using finite element analysis (FEA) and validated through experiments. Heat generation associated with machining is considered and demonstrated to have little impact on LAM. The model indicates that laser power is one critical parameter for successful operation of LAM. Feed and cutting speed can indirectly affect the operating temperatures. Furthermore, a machining model is established with the distinct element method (or discrete element method, DEM) to simulate the dynamic process of LAM. In the microstructural modeling of a [Beta]-type silicon nitride ceramic, clusters are used to simulate the rod-like grains of the silicon nitride ceramic and parallel bonds act as the intergranular glass phase between grains. The resulting temperature-dependent synthetic materials for LAM are calibrated through the numerical compression, bending and fracture toughness tests. The machining model is also validated through experiments in terms of cutting forces, chip size and depth of subsurface damage.
Author: Shuting Lei PhD
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
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Book Description
Author: Xichun Luo
Publisher: Academic Press
ISBN: 0128131136
Category : Mathematics
Languages : en
Pages : 328
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Book Description
Hybrid Machining: Theory, Methods, and Case Studies covers the scientific fundamentals, techniques, applications and real-world descriptions of emerging hybrid machining technology. This field is advancing rapidly in industrial and academic contexts, creating a great need for the fundamental and technical guidance that this book provides. The book includes discussions of basic concepts, process design principles, standard hybrid machining processes, multi-scale modeling approaches, design, on-machine metrology and work handling systems. Readers interested in manufacturing systems, product design or machining technology will find this one-stop guide to hybrid machining the ideal reference. - Includes tables of recommended processing parameters for key engineering materials/products for each hybrid machining process - Provides case studies covering real industrial applications - Explains how to use multiscale modeling for hybrid machining
Author: Mohammed Mudassar Hussain Ansari
Publisher:
ISBN: 9780438855199
Category : Mechanical engineering
Languages : en
Pages : 57
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Book Description
The most commonly used technique for machining ceramics is diamond grinding. It accounts for up to 75% of the manufacturing costs resulting in high cost of the product. An LED bulb offering increased brightness, energy saving and long life by using ceramic integration to LED chips costs around 10 times to a normal LED bulb. Complex geometries used in electronics, medical surgeries, aerospace, and automobile industries require the use of costly molds or powder metallurgy for low batch production which does not justify the cost. Laser Assisted Machining (LAM) is a process that uses a laser to locally heat the surface of a component (made of ceramic), making it more ductile and machinable using conventional machine tools. Recent studies have shown that LAM gives improved material removal rate and surface finishing, and reduces the cost of machining, i.e. around 50% reduction in the manufacturing costs. Physical experiments require the use of advanced instruments and specialized tools making it a difficult and time-consuming process. It is necessary to have a predicting thermal study to help design more efficient physical experiments. In this study, Finite Element Analysis (FEA) has been used to analyze the thermal distribution of a workpiece under rotating and translating moving heat source. In LAM, there are many variables that greatly affect the temperature, such as laser size, laser power, translational velocity, etc. Extensive research has been performed on solid cylinders however many new applications such as thermocouple protection tube, cylinder lining, blasting nozzles, bone fusion in surgeries, etc., require application of hollow cylinders. Therefore, this work intends to perform a thermal study on a ceramic tube when a laser beam moving on its outer surface. As the generated heat due to the machining is insignificant compared to the heat created by the laser heat source, this study doesn't consider the mechanical removal of the material. The ceramic chosen for this study is Silicon Nitride as it is widely used due to its excellent wide range of properties making it suitable for all industries. The FEA method and assumptions that will be used on this research has been verified with previous experimental and numerical research on a solid cylinder.
Author: Sepehr Omidi
Publisher:
ISBN: 9781339455990
Category : Cutting
Languages : en
Pages : 86
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Book Description
Over the last decades Laser Assisted Machining (LAM) of hard materials has grown into a viable solution for the manufacturing industry. Interest in the machining of ceramics has grown due to the possibilities of LAM reducing tool wear and increasing productivity. The concept is based on heating the ceramic material into a soft phase that makes it much easier to machine. The other advantage this technology has over traditional grinding is that is possible to make complex shapes and even machine threads. While there has been research in LAM of ceramics such as Silicon Nitride, Zirconia, Alumina it often lacks comprehensive analysis for a particular laser source. In order for industry to adopt such a technology an optimized approach to providing results on ceramics is required. A few years ago as a result of ongoing research at NIU the commercial technology Easy to Machine Hard Materials (EMHM(TM)) was developed to address this issue. While research of Silicon Nitride, Zirconia, Alumina and Cemented Carbide are ongoing via EMHM the thrust of this research will be to provide a comprehensive approach and reduce the time required to optimize parameters for machining ceramics. The main issue to address for productivity in industry (when machining) is how to minimize tool wear (so tools last longer) while removing as much material as quickly as possible. This will obviously vary based on material and energy available. To experimentally carry all this work out would require a vast amount of resources and time. As such this proposal discusses the development of an easy to use ANSYS simulation program that will enable the user to see the surface temperature (which can translate to tool life) based on the feed rate, depth of cut, laser power and spindle speed. There are complex thermo-mechanical forces at play and so an optimized program is required to improve throughput of the analysis. We will develop the first generation ANSYS simulation which will help us verify experimental work we have done with the materials that have been researched via EMHM(TM).
Author: Li Sun
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
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Book Description
Author: Dehong Huo
Publisher: John Wiley & Sons
ISBN: 1118536614
Category : Technology & Engineering
Languages : en
Pages : 384
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Book Description
Micro-Cutting: Fundamentals and Applications comprehensively covers the state of the art research and engineering practice in micro/nano cutting: an area which is becoming increasingly important, especially in modern micro-manufacturing, ultraprecision manufacturing and high value manufacturing. This book provides basic theory, design and analysis of micro-toolings and machines, modelling methods and techniques, and integrated approaches for micro-cutting. The fundamental characteristics, modelling, simulation and optimization of micro/nano cutting processes are emphasized with particular reference to the predictabilty, producibility, repeatability and productivity of manufacturing at micro and nano scales. The fundamentals of micro/nano cutting are applied to a variety of machining processes including diamond turning, micromilling, micro/nano grinding/polishing, ultraprecision machining, and the design and implementation of micro/nano cutting process chains and micromachining systems. Key features • Contains contributions from leading global experts • Covers the fundamental theory of micro-cutting • Presents applications in a variety of machining processes • Includes examples of how to implement and apply micro-cutting for precision and micro-manufacturing Micro-Cutting: Fundamentals and Applications is an ideal reference for manufacturing engineers, production supervisors, tooling engineers, planning and application engineers, as well as machine tool designers. It is also a suitable textbook for postgraduate students in the areas of micro-manufacturing, micro-engineering and advanced manufacturing methods.
Author:
Publisher: Newnes
ISBN: 0080965334
Category : Technology & Engineering
Languages : en
Pages : 5485
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Book Description
Comprehensive Materials Processing, Thirteen Volume Set provides students and professionals with a one-stop resource consolidating and enhancing the literature of the materials processing and manufacturing universe. It provides authoritative analysis of all processes, technologies, and techniques for converting industrial materials from a raw state into finished parts or products. Assisting scientists and engineers in the selection, design, and use of materials, whether in the lab or in industry, it matches the adaptive complexity of emergent materials and processing technologies. Extensive traditional article-level academic discussion of core theories and applications is supplemented by applied case studies and advanced multimedia features. Coverage encompasses the general categories of solidification, powder, deposition, and deformation processing, and includes discussion on plant and tool design, analysis and characterization of processing techniques, high-temperatures studies, and the influence of process scale on component characteristics and behavior. Authored and reviewed by world-class academic and industrial specialists in each subject field Practical tools such as integrated case studies, user-defined process schemata, and multimedia modeling and functionality Maximizes research efficiency by collating the most important and established information in one place with integrated applets linking to relevant outside sources
Author: Satya Kumar Ajjarapu
Publisher:
ISBN:
Category :
Languages : en
Pages : 240
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Book Description
Developments in precision machining technology have shown that ductile regime machining of advanced ceramics such as Silicon Nitride (Si[subscript]3N[subscript]4) is possible under controlled cutting conditions. In the present work, the mechanics of ductile regime machining of silicon nitride at micron level depths was studied experimentally and numerically. Machining tests were carried out for depths of cut ranging from 250 nm to 10 [mu]m on Diamond Turning Machine (DTM). Force and surface roughness data collected from diamond turning of silicon nitride samples were presented. Chip morphology studies were also carried out using Scanning Electron Microscopy (SEM) for the machined samples. The mechanical behavior of silicon nitride is treated using the Drucker-Prager yield criterion and implemented in the commercial machining software AdvantEdge. Numerical simulations were conducted for depths of cut ranging from 1 [mu]m to 40 [mu]m and at rake angles from 0[superscript]o to -60[superscript]o. Pressure distribution at the tool and workpiece interface for different depths of cut and rake angles was studied. Experimental results were correlated with the numerical results for -5[superscript]o and -45[superscript]o rake angles.
