Multiphysics modeling and experiments of grayscale photopolymerization with application to microlens fabrication

Abstract A phenomenological model of a single-shot grayscale photopolymerization process is developed and used within a virtual process planning framework for microlens fabrication. Along with previous research, the kinetic relations describing the solidification of UV curable resin are derived based on the underlying chemical reactions involved in free radical photopolymerization. As enhancements to the state-of-the-art, our multiphysics model includes a recently proposed super-Gaussian description of the light field, as well as the photobleaching effect due to the live reduction in photoinitiator concentration during UV illumination. In addition, heat generation and thermal strains due to the exothermic chemical reactions, and chemical shrinkage due to polymerization and cross-linking of monomers are considered. The model is numerically implemented via finite element method in COMSOL Multiphysics software. Using a simulation-based virtual process planning framework, customized microlenses are fabricated with an in-house grayscale lithography experimental setup for digital micromirror device (DMD)-based volumetric additive manufacturing. Simulation and experimental results show that after the end of exposure, the temperature quickly rises by the advancement of exothermic chemical reactions and reaches a maximum rise of 100 K in a few seconds, followed by a slow cooling and recovery of thermal strains. It is observed that chemical and thermal shrinkages can compromise the dimensional accuracy of the final part near the resin-substrate interface due to the strong adhesion of the solidified part to the rigid substrate that prevents material shrinkage in the vicinity of the rigid substrate.

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Dynamic model identification for CNC machine tool feed drives from in-process signals for virtual process planning

Mechatronics ◽

10.1016/j.mechatronics.2020.102445 ◽

2020 ◽

Vol 72 ◽

pp. 102445

Author(s):

Mustafa Hakan Turhan ◽

Ginette Wei Get Tseng ◽

Kaan Erkorkmaz ◽

Baris Fidan

Keyword(s):

Machine Tool ◽

Dynamic Model ◽

Process Planning ◽

Model Identification ◽

Cnc Machine Tool ◽

Cnc Machine ◽

Feed Drives ◽

Virtual Process

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The Effect of Machining Toolpath on Surface Roughness and Dimensional Accuracy for High-Speed Micro Milling

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.261.69 ◽

2017 ◽

Vol 261 ◽

pp. 69-76

Author(s):

Amin Dadgari ◽

De Hong Huo ◽

David Swailes

Keyword(s):

Surface Roughness ◽

Process Planning ◽

Tool Path ◽

Dimensional Accuracy ◽

Machining Process ◽

Micro Milling ◽

Geometric Features ◽

Machining Parameters ◽

Machining Performance ◽

Planning Stage

This paper investigates different machining toolpath strategies on machining efficiency and accuracy in the micro milling of linear and circular micro geometric features. Although micro milling includes many characteristics of the conventional machining process, detrimental size effect in downscaling of the process can lead to excessive tool wear and machining instability, which would, in turn, affects the geometrical accuracy and surface roughness. Most of the research in micro milling reported in literature focused on optimising specific machining parameters, such as feed rate and depth of cut, to achieve lower cutting force, better surface roughness, and higher material removal rate. However, there was little attention given to the suitability and effect of machining tool path strategies. In this research, a tool path optimisation method with respect to surface roughness and dimensional accuracy is proposed and tested experimentally. Various toolpath strategies, including lace(0°), lace(45°), lace(90°), concentric and waveform in producing linear and circular micro geometric features were compared and analysed. Experimental results show that the most common used strategies lace(0°) and concentric reported in the literature have provided the least satisfactory machining performance, while waveform toolpath provides the best balance of machining performance for both linear and circular geometries. Hence, at process planning stage it is critical to assign a suitable machining toolpath strategy to geometries accordingly. The paper concludes that an optimal choice of machining strategies in process planning is as important as balancing machining parameters to achieve desired machining performance.

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Analysis of the Performance of Drilling Operations for Improving Productivity

10.5772/intechopen.96497 ◽

2021 ◽

Author(s):

Majid Tolouei-Rad ◽

Muhammad Aamir

Keyword(s):

High Speed ◽

Cutting Tools ◽

High Speed Steel ◽

Dimensional Accuracy ◽

Vital Role ◽

Machining Process ◽

Drilling Process ◽

Single Shot ◽

Drilling Operations

Drilling is a vital machining process for many industries. Automotive and aerospace industries are among those industries which produce millions of holes where productivity, quality, and precision of drilled holes plays a vital role in their success. Therefore, a proper selection of machine tools and equipment, cutting tools and parameters is detrimental in achieving the required dimensional accuracy and surface roughness. This subsequently helps industries achieving success and improving the service life of their products. This chapter provides an introduction to the drilling process in manufacturing industries which helps improve the quality and productivity of drilling operations on metallic materials. It explains the advantages of using multi-spindle heads to improve the productivity and quality of drilled holes. An analysis of the holes produced by a multi-spindle head on aluminum alloys Al2024, Al6061, and Al5083 is presented in comparison to traditional single shot drilling. Also the effects of using uncoated carbide and high speed steel tools for producing high-quality holes in the formation of built-up edges and burrs are investigated and discussed.

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ASUPPA: A Framework for Interactive and Iterative Synthesis and Improvement of Process Plans

Volume 1: 20th Computers and Information in Engineering Conference ◽

10.1115/detc2000/cie-14628 ◽

2000 ◽

Author(s):

Xiaomin Li ◽

Subbarao Kambhampati ◽

Jami Shah

Keyword(s):

Process Planning ◽

Search Space ◽

Organizational Resistance ◽

Context Sensitive ◽

Process Plans ◽

Search Mechanism ◽

Planning Framework ◽

Planning Methods ◽

Complete Automation ◽

Iterative Synthesis

Abstract The limited success and acceptance of automated process planning methods in the industry can be traced to the fact that most existing approaches aim at complete automation. We believe that the quest for complete automation is flawed, both because in practice optimality metrics for process plans are context-sensitive, and because there is significant organizational resistance to approaches that completely eliminate humans from the process planning framework. In this paper, we present an interactive and iterative planning framework, called ASUPPA, which focuses instead on providing intelligent assistance to a human process planner. After generating a “good” default process plan, ASUPPA engages in a “present – elicit criticism – revise” loop with an expert process planner. To operate successfully, ASUPPA needs access to the full search space of process plans, and have the ability to incrementally modify plans in response to expert criticism. The former is provided by basing ASUPPA on ASU Features Testbed, a comprehensive and systematic framework for recognizing and reasoning with features in machinable parts. To support the latter, the system is equipped with an iterative and interactive search mechanism. We will discuss the operational details of the resultant system, called ASUPPA.

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Synthesis of UV Curable Polymethylsilane by a one-Step Wurtz Route

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.233-235.250 ◽

2011 ◽

Vol 233-235 ◽

pp. 250-253

Author(s):

Yi He Li ◽

Qing Ling Fang ◽

Chun Yu Wang ◽

Wen Sen Chang ◽

Xiao Dong Li

Keyword(s):

Chemical Reactions ◽

Molecular Structures ◽

Promising Candidate ◽

Uv Curable ◽

One Step ◽

Ft Ir

UV curable vinylic polymethylsilane (v-PMS) was synthesized by a facile one-step Wurtz route, the products’ molecular structures were characterized by FT-IR and the mechanism of the chemical reactions was discussed in detail. The as-synthesized product was a promising candidate for the fabrication of micro ceramic structures for microfluidics by softlithography techniques.

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Integrate Manufacturing Planning to Cloud Manufacturing Framework

Volume 4: Bio and Sustainable Manufacturing ◽

10.1115/msec2017-3047 ◽

2017 ◽

Author(s):

Xiangyun Li ◽

Luping Zhang ◽

Chunxia Yu

Keyword(s):

Process Planning ◽

Cloud Manufacturing ◽

Concrete Case ◽

Planning And Scheduling ◽

Operational Mechanism ◽

Manufacturing Planning ◽

Sustainable Environment ◽

Planning Framework ◽

New Framework

We provide a cloud manufacturing based manufacturing planning framework for small and medium-sized enterprises. Manufacturing planning is conducted by separate units in the cloud instead of in corporations or manufacturing platforms. Disorders can be removed by the adoption of our newly-introduced units. To retain the workability of our new framework, three assumptions are imposed. A concrete case on process planning and scheduling is used for illustration of the necessity of our assumptions and operational mechanism of our design. Finally, a preliminary discuss on how intellect resources as well as small and medium-sized enterprises are involved to create a sustainable environment for small and medium-sized enterprises is placed.

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Probe into CO2-Coal Interactions with Differential Scanning Calorimetry

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.953-954.1286 ◽

2014 ◽

Vol 953-954 ◽

pp. 1286-1292 ◽

Cited By ~ 1

Author(s):

Li Jiang Duan ◽

Liang Chao Qu

Keyword(s):

Differential Scanning Calorimetry ◽

Chemical Reactions ◽

Active Sites ◽

Bituminous Coal ◽

Shanxi Province ◽

Heating Process ◽

Side Chains ◽

Scanning Calorimetry ◽

Slow Cooling ◽

Two Factors

In order to probe CO2-coal interactions, differential scanning calorimetry (DSC) experiment was carried out in the atmosphere of He and CO2with coals from Huozhou, Changzhi and Jincheng areas in Shanxi Province (classified as high-volatile bituminous coal, low-volatile bituminous coal and anthracite, respectively). It was found that, in a He atmosphere, all the three curves show no enthalpy and are almost reversible, indicating no adsorption occurs. However, in a CO2atmosphere, all the three curves show exothermic peaks and endothermic peaks and are irreversible, indicating, except for physical reactions, chemical reactions may also occur. It was proposed that the C atom of CO2accepted electrons from coal molecular, and formed an electron donor-acceptor complex (i.e., an EDA complex), in other words, chemical reactions occured, hence exothermic peaks occured. The interconnections of the active sites to other groups in coal molecular are weakened due to the formation of EDA complexes, so easily to be broken during heating, hence endothermic peaks occured. The irreversibility of the curves indicate structure change of coal, which may be influenced by two factors: a) during slow cooling, the ordering of side chains, which were expanded in high temperature, leads to a less associated structure; b) in heating process, the breakage of side chains enhances the associations of coal macromolecular, and leads to a more highly associated structure.

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