Download or read book Experimental and Numerical Analyses of Ductile Regime Machining of Silicon Nitride written by Satya Kumar Ajjarapu and published by . This book was released on 2004 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Experimental and Numerical Studies on Ductile Regime Machining of Silicon Carbide and Silicon Nitride written by Ravishankar Mariayyah and published by . This book was released on 2003 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of Ductile Machining of Silicon Nitride written by Thimmaiah Ganapathi Kumbera and published by . This book was released on 2001 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Machining of brittle materials presently involves time consuming operations such as grinding and polishing. Recent work has introduced ductile regime machining as a viable alternative to existing finishing operations in machining of brittle materials. In this work, the mechanics of ductile machining of Silicon Nitride (Si3N4) with a single point cutting tool is studied. Experimental work was carried out to determine the mode of material removal during the process. The main objective of the experimental study was to obtain the threshold values of the machining parameters for ductile machining. Surface analysis for possible fracture and chip morphology was also carried out. The orthogonal cutting process is modeled using the finite element analysis software ADVANTEDGE. Various conditions of temperatures, pressures and stresses that are conducive to ductile material removal are studied via parametric study of the effects of machining parameters on the process.
Download or read book Ductile Regime Machining of Silicon Nitride written by Satya K. Ajjarapu and published by . This book was released on 2000 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental and Numerical Investigation of Laser Assisted Milling of Silicon Nitride Ceramics written by Budong Yang and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Investigation of Cutting Mechanics in Single Point Diamond Turning of Silicon written by Amir Mir and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: As a kind of brittle material, silicon will undergo brittle fracture at atmospheric pressure in conventional scale machining. Studies in the last two decades on hard and brittle materials including silicon, germanium, silicon nitride and silicon carbide have demonstrated ductile regime machining using single point diamond turning (SPDT) process. The mirror-like surface finish can be achieved in SPDT provided appropriate tool geometry and cutting parameters including feed rate, depth of cut and cutting speed are adopted.The research work in this thesis is based on combined experimental and numerical smoothed particle hydrodynamics (SPH) studies to provide an inclusive understanding of SPDT of silicon. A global perspective of tool and workpiece condition using experimental studies along with localized chip formation and stress distribution analysis using distinctive SPH approach offer a comprehensive insight of cutting mechanics of silicon and diamond tool wear. In SPH modelling of SPDT of silicon, the distribution of von Mises and hydrostatic stress at incipient and steady-state was found to provide the conditions pertinent to material failure, phase transformation, and ductile mode machining. The pressure-sensitive Drucker Prager (DP) material constitutive model was adopted to predict the machining response behaviour of silicon during SPDT. Inverse parametric analysis based on indentation test was carried out to determine the unknown DP parameters of silicon by analysing the loading-unloading curve for different DP parameters. A very first experimental study was conducted to determine Johnson-Cook (J-C) model constants for silicon. High strain rate compression tests using split Hopkinson pressure bar (SHPB) test as well as quasi-static tests using Instron fatigue testing machine were conducted to determine J-C model constants.The capability of diamond tools to maintain expedient conditions for high-pressure phase transformation (HPPT) as a function of rake angle and tool wear were investigated experimentally as well as using SPH approach. The proportional relationship of cutting forces magnitude and tool wear was found to differ owing to wear contour with different rake angles that influence the distribution of stresses and uniform hydrostatic pressure under the tool cutting edge. A new quantitative evaluation parameter for the tool wear resistance performance based on the cutting distance was also proposed. It was also found that the machinability of silicon could be improved by adopting novel surface defect machining (SDM) method.The ductile to brittle transition (DBT) with the progressive tool wear was found to initiate with the formation of lateral cracks at low tool wear volume which transform into brittle pitting damage at higher tool edge degradation. A significant variation in resistance to shear deformation as well as position shift of the maximum stress values was observed with the progressive tool wear. The magnitude and distribution of hydrostatic stress were also found to change significantly along the cutting edge of the new and worn diamond tools.
Download or read book Precision Engineering written by M. V. Suryaprakash and published by Alpha Science Int'l Ltd.. This book was released on 2004 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: The current focus of manufacturing is towards flexible automation and miniaturization.
Download or read book Numerical Modeling and Experimental Investigation of Laser assisted Machining of Silicon Nitride Ceramics written by Xinwei Shen and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Properties and Applications of Silicon Carbide written by Rosario Gerhardt and published by BoD – Books on Demand. This book was released on 2011-04-04 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, we explore an eclectic mix of articles that highlight some new potential applications of SiC and different ways to achieve specific properties. Some articles describe well-established processing methods, while others highlight phase equilibria or machining methods. A resurgence of interest in the structural arena is evident, while new ways to utilize the interesting electromagnetic properties of SiC continue to increase.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1992 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Diamond Turning of Silicon Nitride written by Ronnie Rex Fesperman and published by . This book was released on 2004 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes experimental work carried out to study the ability to ductile single point diamond turn both Ceradyne's Ceralloy 147-31N and Allied Signal's GS-44 silicon nitride (Si[subscript]3N[subscript]4) and the effect single point diamond turning has on the strength of GS-44 Si[subscript]3N[subscript]4. The Nanocut II nanometric cutting instrument was first employed to determine if the critical depth of cut, corresponding to a ductile to brittle transition, for 147-31N Si[subscript]3N[subscript]4 was within the nanometric regime. A Precitech Nanoform 350 diamond turning machine was then employed to determine the limits of ductile regime machining at larger depths of cut for 147-3 IN and GS-44 Si[subscript]3N[subscript]4 . An investigation into the ability to diamond turn Si[subscript]3N[subscript]4 with both single crystal and polycrystalline diamond tools was performed. 140 GS-44 rectangular flexural bar test specimens in four sample sets of 35 specimens each were prepared by diamond turning with polycrystalline diamond tools at depths of 250 nm, 500 nm, 5 [mu]m, and 10 [mu]m. Four-point flexure testing was performed on the diamond turned flexure bars as well as flexure bars prepared by grinding to assess the effect single point polycrystalline diamond turning has on the strength of GS-44 Si[subscript]3N[subscript]4 in comparison to grinding. Fractography was carried out to identify the origin of failure of each specimen and Weibull statistical analysis was used to characterize the strength distribution for each machining condition. Finally, the effect of negative rake angle and rate of tool wear of single crystal diamond tools was studied by diamond turning thin disks of GS-44 Si[subscript]3N[subscript]4.
Download or read book Experimental and Numerical Study of Silicon Nitride for Powder Injection Moulding written by Leslie Poh Ping Yi and published by . This book was released on 2019 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental and Numerical Study of Silicon Nitride for Powder Injection Moulding written by Ping Yi Poh and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced Methods in Materials Processing Defects written by M. Predeleanu and published by Elsevier. This book was released on 1997-06-18 with total page 439 pages. Available in PDF, EPUB and Kindle. Book excerpt: This collection of papers focus on advanced methods for predicting and avoiding the occurrence of defects in manufactured products. A new feature is included, namely, the influence of the processing-induced defects on the integrity of structures.The following topics are developed: damage modeling; damage evaluation and rupture; strain localization and instability analysis; formability characterization; prediction of shape inaccuracies; influence of defects on structural integrity. The main manufacturing operations are covered and various materials are examined, such as new and conventional metal alloys, ceramics, polymers and composites.
Download or read book Engineered Materials Abstracts written by and published by . This book was released on 1993-10 with total page 826 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ceramic Abstracts written by and published by . This book was released on 1997 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt:
