Download or read book Simulating the Precision Glass Molding Process written by Fei Wang and published by . This book was released on 2014-04-22 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling Fracture Behavior in Precision Glass Molding written by Gang Liu and published by Apprimus Wissenschaftsverlag. This book was released on 2018-08-21 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: A temperature and strain rates dependent fracture model is developed based on Weibull statistics to quantitatively describe the brittle-ductile transition of glass fracture in precision glass molding process. Under the assistance of FEM simulation, this fracture model can be used to calculate the fracture probability of glass during the precision glass molding process. Meanwhile, the most probable fracture timing, location of fracture initiation and fracture pattern can be also predicted.
Download or read book Comparison of Computational Modeling of Precision Glass Molding of Infrared Lenses written by Mohamad Amin Moghaddas and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of manufacturing process of an infrared lens by using a commercial glass molding machine, GP-10000HT, is the second step to figure out all the details of a real precision glass molding process that help us to provide a simulation that makes a better prediction of glass molding process.
Download or read book Design and Fabrication of Nonconventional Optical Components by Precision Glass Molding written by Peng He and published by . This book was released on 2014 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Precision glass molding is a net-shaping process to fabricate glass optics by replicating optical features from precision molds to glass at elevated temperature. The advantages of precision glass molding over traditional glass lens fabrication methods make it especially suitable for the production of optical components with complicated geometries, such as aspherical lenses, diffractive hybrid lenses, microlens arrays, etc. Despite of these advantages, a number of problems must be solved before this process can be used in industrial applications. The primary goal of this research is to determine the feasibility and performance of nonconventional optical components formed by precision glass molding. This research aimed to investigate glass molding by combing experiments and finite element method (FEM) based numerical simulations. The first step was to develop an integrated compensation solution for both surface deviation and refractive index drop of glass optics. An FEM simulation based on Tool-Narayanaswamy-Moynihan (TNM) model was applied to predict index drop of the molded optical glass. The predicted index value was then used to compensate for the optical design of the lens. Using commercially available general purpose software, ABAQUS, the entire process of glass molding was simulated to calculate the surface deviation from the adjusted lens geometry, which was applied to final mold shape modification. A case study on molding of an aspherical lens was conducted, demonstrating reductions in both geometry and wavefront error by more than 60%.
Download or read book The Failure Mechanisms of Coated Precision Glass Molding Tools written by Kyriakos Georgiadis and published by Apprimus Wissenschaftsverlag. This book was released on 2015-10-19 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molding tools in precision glass molding fail easily, even with protective thin film coatings applied. In this work, various efficient methods for assessing glass-coating interactions are developed, including a new, automated testing rig. Analysis of the testing results provides a better understanding of these mechanisms and how they are influenced by material properties and process parameters, so that the appropriate measures can be taken to prolong the life of the molding tools.
Download or read book Precision Lens Molding of Glass A Process Perspective written by Jayson J. Nelson and published by Springer Nature. This book was released on 2020-04-10 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights the tools and processes used to produce high-quality glass molded optics using commercially available equipment. Combining scientific data with easy-to-understand explanations of specific molding issues and general industry information based on firsthand studies and experimentation, it provides useful formulas for readers involved in developing develop in-house molding capabilities, or those who supply molded glass optics. Many of the techniques described are based on insights gained from industry and research over the past 50 years, and can easily be applied by anyone familiar with glass molding or optics manufacturing. There is an abundance of information from around the globe, but knowledge comes from the application of information, and there is no knowledge without experience. This book provides readers with information, to allow them to gain knowledge and achieve success in their glass molding endeavors.
Download or read book A Computational Tool for Numerical Prediction of Precision Glass Molding Process written by Shriram Palanthandalam Madapusi and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Molding process which would generate residual stresses within acceptable limits and design appropriate mold geometry that can yield the correct shape of the final glass optics.
Download or read book Trade Products of the British Empire written by and published by . This book was released on 1919 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Optical Effects of Chalcogenide Glass in Precision Glass Molding and Applications on Infrared Micro Optical Manufacturing written by Lin Zhang and published by . This book was released on 2019 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: Precision glass molding (PGM) is being considered as an alternative to traditional methods of manufacturing large-volume, high-quality and low-cost optical components. In this process, glass optics is fabricated by replicating optical features from precision molds to glass at elevated temperature. Chalcogenide glasses are emerging as alternative infrared materials for their wide range infrared transmission, high refractive index and low phonon energy. In addition, chalcogenide glasses can be readily molded into precision optics at elevated temperature, slightly above its glass transition temperature (Tg), which in general is much lower compared to oxide glasses. The primary goal of this research is to evaluate the thermoforming mechanism of chalcogenide glass around Tg and investigate its refractive index change and residual stresses in molded lens in and post PGM. Firstly, a constitutive model is introduced to precisely predict the material behavior in PGM by integrating subroutines into a commercial finite element method (FEM) software. This modeling approach utilizes the Williams-Landel-Ferry (WLF) equation and Tool-Narayanaswamy-Moynihan (TNM) model to describe (shear) stress relaxation and structural relaxation behaviors, respectively. It is predicted that `index drop’ occurred inside the molded prism due to rapid thermal cycling and the cooling rate above Tg can introduce large geometry deviations to the molded optical lens. Secondly, the refractive index variations inside molded lenses are further evaluated by measuring deviation angle through a prism & wavefront changes through molded lens using a Shack-Hartmann wavefront sensor (SHS), while the residual stresses trapped inside the molded lenses are obtained by using a birefringence method. Measured results of the molded infrared lenses combining numerical simulation provide an opportunity for optical manufacturers to achieve a better understanding of the mechanism and optical performance variation of chalcogenide glasses in and post PGM. Upon completion of the aforementioned research, two typical micro IR optics are designed, fabricated and tested, an infrared SHS and a large field-of-view (FOV) microlens array, as demonstrations. A novel fabrication method combining virtual spindle based high-speed single-point diamond milling and PGM process is adopted to fabricate infrared microlens array. The uniqueness of the virtual spindle based single-point diamond milling is that the surface features can be constructed sequentially by spacing the virtual spindle axis at an arbitrary position based on a combination of rotational and transitional motions of the machine tool. After the mold insert is machined, it is employed to replicate the optical profile onto chalcogenide glass. On the other hand, an infrared compound-eye system consisting of 3×3 channels for a FOV of 48°×48° is developed. The freeform microlens array on a flat surface is utilized to steer and focus the incident light from all three dimensions (3D) to a two-dimension (2D) infrared imager. Using raytracing, the profiles of the freeform microlenses of each channel are optimized to obtain the best imaging performance. To avoid crosstalk among adjacent channels, a micro aperture array fabricated by 3D printing is mounted between the microlens array and IR imager. The imaging tests of the infrared compound-eye imaging system show that the asymmetrical freeform lenslets are capable of steering and forming legible images within the design FOV. Compared to a conventional infrared camera, this novel microlens array can achieve a considerably larger FOV while maintaining low manufacturing cost without sacrificing image quality. Finally, two rapid heating processes are explored and demonstrated by using graphene-coated silicon as an effective and high-performance mold material for precision glass molding. One process is based on induction heating and the other one is based on mid-infrared radiation. Since the graphene coating is very thin (~45 nm), a high heating rate of 5~20 °C/s can be achieved. The contact surface of the Si mold and the polymer substrate can be heated above the Tg within 20 s and subsequently cooled down to room temperature within tens of seconds after molding. The feasibility of this process is validated by the fabrication of optical gratings, micropillar matrices, and microlens arrays on polymethylmethacrylate (PMMA) substrate with high precision. The uniformity and surface geometries of the replicated optical elements are evaluated using an optical profilometer. Compared with conventional bulk heating molding process, this novel rapid localized heating process could improve replication efficiency with better geometrical fidelity.
Download or read book Modeling Sticking Force in Compression Glass Molding Systems written by Kyle David Fischbach and published by . This book was released on 2010 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Compression molding of glass is a promising manufacturing process for high precision, low cost glass optical elements. However, the conditions that glass molding processes are performed in are known to cause sticking between the glass work piece and the mold surface. When the glass-mold contact is repeated during heating-cooling cycles, some or all of a glass specimen often remains on a mold surface during de-molding and damages the formally high precision mold surface. In order to decrease the mold sticking and mold damage, mold materials for glass molds need to have high hardness, heat resistance, and chemical stability. Two examples of mold materials include tungsten carbide and silicon. The microstructures of popular mold materials such as WC-Co contain spots of a lower mechanical strength soft cobalt bonding agent that could adhere to the glass under high molding temperatures. To mitigate the problem, a thin layer coating of inert materials such as platinum or diamond like coating is deposited on the mold surface. In this research, two different coatings were applied to both tungsten carbide and silicon wafer substrates and then tested in a real molding environment. A new system was fabricated to test sticking force between the glass pieces and glass molds. Experiments demonstrated processing parameters including the level of compression, the time associated with compression and the time allowed for cooling significantly affected the glass to mold sticking force.
Download or read book Microfabrication and Precision Engineering written by J. Paulo Davim and published by Woodhead Publishing. This book was released on 2016-11-19 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microfabrication and precision engineering is an increasingly important area relating to metallic, polymers, ceramics, composites, biomaterials and complex materials. Micro-electro-mechanical-systems (MEMS) emphasize miniaturization in both electronic and mechanical components. Microsystem products may be classified by application, and have been applied to a variety of fields, including medical, automotive, aerospace and alternative energy. Microsystems technology refers to the products as well as the fabrication technologies used in production. With detailed information on modelling of micro and nano-scale cutting, as well as innovative machining strategies involved in microelectrochemical applications, microchannel fabrication, as well as underwater pulsed Laser beam cutting, among other techniques, Microfabrication and Precision Engineering is a valuable reference for students, researchers and professionals in the microfabrication and precision engineering fields. Contains contributions by top industry experts Includes the latest techniques and strategies Special emphasis given to state-of-the art research and development in microfabrication and precision engineering
Download or read book Experimental and Numerical Analysis of Thermal Forming Processes for Precision Optics written by Lijuan Su and published by . This book was released on 2010 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Glass has been fabricated into different optical elements including aspherical lenses and freeform mirrors. However, aspherical lenses are very difficult to manufacture using traditional methods since they were specially developed for spherical lenses. On the other hand, large size mirrors are also difficult to make especially for high precision applications or if designed with complicated shapes. Recently developed two closely related thermal forming processes, i.e. compression molding and thermal slumping, have emerged as two promising methods for manufacturing aspherical lenses and freeform mirrors efficiently. Compression molding has already been used in industry to fabricate consumer products such as the lenses for digital cameras, while thermal slumping has been aggressively tested to create x-ray mirrors for space-based telescopes as well as solar panels. Although both process showed great potentials, there are a quite few technical challenges that prevent them from being readily implemented in industry for high volume production. This dissertation research seeks a fundamental understanding of the thermal forming processes for both precision glass lenses and freeform mirrors by using a combined experimental, analytical and numerical modeling approach. First, a finite element method (FEM) based methodology was presented to predict the refractive index change of glass material occurred during cooling. The FEM prediction was then validated using experimental results. Second, experiments were also conducted on glass samples with different cooling rates to study the refractive index variation caused by non-uniform cooling. A Shack-Hartmann Sensor (SHS) test setup was built to measure the index variations of thermally treated glass samples. Again, an FEM simulation model was developed to predict the refractive index variation. The prediction was compared with the experimental result, and the effects of different parameters were evaluated. In the last phase of this dissertation research, an FEM simulation model was developed to study the thin glass slumping processes on both concave and convex mandrels. Simulation of thin glass sheet slumping on convex mandrel was performed to study the effects of different process parameters, i.e. thickness of the glass sheet, cooling and heating rate, soaking time and soaking temperature. Finally, experiments of thermal slumping glass plates on a parabolic concave mandrel were performed to study the thickness effect on slumping process and the final surface contour of the upper surface of the glass plate. Simulation was again conducted to predict the surface contour. The comparison between simulation and experiments showed that the FEM simulation is adequate for predicting the surface contour if the glass was fully slumped. It was also discovered that for process conditions used, thinner glass sheets were not fully slumped.
Download or read book Molded Optics written by Michael Schaub and published by CRC Press. This book was released on 2016-04-19 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: While several available texts discuss molded plastic optics, none provide information on all classes of molded optics. Filling this gap, Molded Optics: Design and Manufacture presents detailed descriptions of molded plastic, glass, and infrared optics. Since an understanding of the manufacturing process is necessary to develop cost-effective, produ
Download or read book 77th Conference on Glass Problems written by S. K. Sundaram and published by John Wiley & Sons. This book was released on 2017-06-22 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is part of the Ceramic Engineering and Science Proceeding (CESP) series. This series contains a collection of papers dealing with issues in both traditional ceramics (i.e., glass, whitewares, refractories, and porcelain enamel) and advanced ceramics. Topics covered in the area of advanced ceramic include bioceramics, nanomaterials, composites, solid oxide fuel cells, mechanical properties and structural design, advanced ceramic coatings, ceramic armor, porous ceramics, and more.
Download or read book Fabrication of Complex Optical Components written by Ekkard Brinksmeier and published by Springer Science & Business Media. This book was released on 2012-09-14 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: High quality optical components for consumer products made of glass and plastic are mostly fabricated by replication. This highly developed production technology requires several consecutive, well-matched processing steps called a "process chain" covering all steps from mold design, advanced machining and coating of molds, up to the actual replication and final precision measurement of the quality of the optical components. Current market demands for leading edge optical applications require high precision and cost effective parts in large volumes. For meeting these demands it is necessary to develop high quality process chains and moreover, to crosslink all demands and interdependencies within these process chains. The Transregional Collaborative Research Center "Process chains for the replication of complex optical elements" at Bremen, Aachen and Stillwater worked extensively and thoroughly in this field from 2001 to 2012. This volume will present the latest scientific results for the complete process chain giving a profound insight into present-day high-tech production.
Download or read book Frontiers of Manufacturing Science and Measuring Technology II written by Wen Pei Sung and published by Trans Tech Publications Ltd. This book was released on 2012-04-12 with total page 1870 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume is indexed by Thomson Reuters CPCI-S (WoS). This book brings together 389 pieces of peer- This book brings together 389 peer-reviewed papers on Manufacturing Science and Measuring Technology. It provides the reader with a broad overview of the latest advances in the field of manufacturing science and measuring technology. It is divided into: Chapter 1: Manufacturing and Design Science; Chapter 2: Materials Science and Engineering; Chapter 3: Measuring Technology and Mechatronics.
Download or read book Investigation of Injection Molding Process for High Precision Polymer Lens Manufacturing written by Chunning Huang and published by . This book was released on 2008 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Injection molding polymer optical components have long been used for its high volume, low cost and lightweight capability over traditional glass optics. However, the process has not been readily accepted in precision optical fabrication industry because several difficult issues such as geometry deviation, inhomogeneous index distribution, birefringence and freeform fabrication have hindered the implementation of injection molding process in high precision optical applications. This dissertation research was an attempt to create a methodology for injection molding process for high precision polymer lens manufacturing. The study included both experimental approach and numerical modeling in order to identify the proper polymer lens manufacturing processes. The scope of this research involved in both fundamental and systematic investigation in optical design, mold and lens fabrication, as well as optical metrology issues related to polymer lens manufacturing to obtain precision macro and micro polymer freeform optics with accurate geometry and proper optical performance by the state-of-the-art mold fabrication and molding technology. With the aid of DOE (design of experiment) and DEA (data envelopment analysis) methods, the critical process parameters were narrowed down and the optimal conditions were determined for lens geometry compensation. The mold compensation methodology was developed based on advanced freeform measurement and data analysis technology and slow tool servo freeform mold fabrication. The effects of the process parameters on optical performance such as birefringence, index distribution and surface scattering were carefully studied by theoretical and empirical analysis. Due to the complexity of the injection molding process, single process condition cannot fulfill all the requirements for lens quality, therefore balanced process parameters need to be selected as a compromise for desired specifications. Moreover, fabrication of macro Alvarez lens, micro Alvarez lens array, diffractive lens and Fresnel lens has proven that the advanced mold fabrication and injection molding process can provide an easy and quick solution for freeform optics. In addition, simulation with Moldflow MPI6.1 was implemented to verify the experiment results and the prediction of the simulation results was validated using experiment results. Experimental results also showed that injection molding process is capable for precision optics manufacturing with accurate mold compensation and process control.
