Computer-aided design and optimization of profile extrusion dies for thermoplastics and rubber: a review

2011 ◽  
Vol 225 (4) ◽  
pp. 280-321 ◽  
Author(s):  
J F T Pittman
Keyword(s):  
Design Optimization ◽  
Computer Aided Design ◽  
Cross Flow ◽  
Wall Slip ◽  
Economic Benefits ◽  
Die Design ◽  
Computer Assisted ◽  
Extrudate Swell ◽  
Design And Optimization ◽  
Extrusion Dies

A review is provided of issues and techniques in design and optimization of profile extrusion dies for thermoplastics and rubber, with particular emphasis on unplasticized polyvinyl chloride and rubber compounds. Traditional profile die design methods are contrasted with computer-based ones, with respect to efficiency and economic benefits. The main types of die construction are outlined. Physical phenomena relevant to the design and performance of dies are summarized, including: rheology and kinematics of the flow, wall slip, extrusion instabilities, residence time and degradation, extrudate swell, draw-down, and thermal effects. Approaches and strategies for die design are explained, including: flow balancing – with guidance from analytic flow results, the Avoid-Cross-Flow strategy, use of flow separators, and designing for extrudate swell. Published computer simulations of die flow used to assist with design are reviewed. Introducing automatic die design, the structure and elements of a computerized design optimization environment are set out. Key components and options within this are described, including: objective functions, constraints, design variables, optimization algorithms, design parameterization and flow domain meshing, and optimization strategies. Published implementations of computerized profile die design optimization are described. Automatic design optimization is compared with the work of a designer assisted by flow simulations in the industrial environment, showing how substantial reductions in demands on the designer's time are possible. The nature and potential of robust design is outlined, with techniques for its implementation. Conclusions are drawn as to the present state of the art in computer-assisted profile die design and optimization, and potential advances.

scholarly journals Internal Flow Optimization in a Complex Profile Extrusion Die Using Flow Restrictors and Flow Separators

2021 ◽  
Author(s):  
Jingyang Xing ◽  
Majed Alsarheed ◽  
Animesh Kundu ◽  
John P. Coulter
Keyword(s):  
Velocity Distribution ◽  
Cross Flow ◽  
Internal Flow ◽  
Outer Wall ◽  
Die Design ◽  
Cross Sectional ◽  
Polymer Flow ◽  
Extrusion Dies ◽  
Flow Imbalance ◽  
Distinct Features

Abstract The control of flow balance at the die exit is the key for successful extrusion of polymers. The complex cross-sectional variation in real-world hollow extrusion profiles intrinsically promotes flow imbalance in the die cavity. Special considerations are required for designing extrusion dies for such profiles. The die design for a complex door frame profile was computationally optimized in this study with the aid of a commercially available software package. The velocity distribution at the die exit, post-die extrudate deformation, temperature distribution, and pressure distribution of a traditional die was investigated in detail and found to be inadequate. A modified die incorporated three distinct features, flow restrictors, flow separators and approach angle of the torpedoes, to achieve a balanced and uniform velocity at the die exit. The flow restrictors and flow separators were added in the pre-parallel zone. Flow restrictors were added on top and bottom of the torpedoes to increase the restriction on polymer flow. A unique inclined flow restrictor was introduced to achieve uniform internal melt flow. Flow separators were added at junctions of outer wall and inner vertical walls to separate the polymer flow into different sections and minimize cross flow between these sections. The addition of these features proved to be highly effective for balancing the velocity distribution at the die exit. The combination of 3-D modeling and simulation is an effective cost and time efficient approach for optimizing complex die designs before manufacturing.

Computer Assisted Design and Structural Topology Optimization of Customized Craniofacial Implants

2017 ◽  
Author(s):  
Carlos A. Gómez Pérez ◽  
Hugo I. Medellín-Castillo ◽  
Raquel Espinosa-Castañeda
Keyword(s):  
Topology Optimization ◽  
Computer Aided Design ◽  
3D Model ◽  
Titanium Implants ◽  
Computer Assisted ◽  
Structural Topology ◽  
Design And Optimization ◽  
Cad System ◽  
Modern Engineering ◽  
Craniofacial Implants

Modern design and manufacturing engineering technologies have greatly improved the way in which modern craniofacial implants are designed and fabricated. However, few efforts have been made in order to optimize their design. While the weight of polymer-based implants (e.g. PMMA implants) may not affect the patient’s comfort, the higher weight of metal-based implants (e.g. titanium implants), could greatly affect the patient’s comfort, causing in some cases nuisances and imbalance problems. Thus, the optimization of the implant becomes relevant in order to guarantee its structural stiffness but with a reduced weight. In this paper, the design and structural optimization of customized craniofacial implants based on the use of modern engineering technologies is presented. The aim is to introduce an engineering methodology for the design and optimization of customized craniofacial implants. The methodology starts from the patient’s medical images, obtained from a computerized tomography (CT), which are processed to reconstruct the digital 3D model. Next, the geometrical design of the implant is carried out in a computer aided design (CAD) system using the patient’s 3D model. Then, the structural analysis of the implant is performed using the Finite Element Method (FEM) and considering a quasi-static load. The topology optimization of the implant is made using the Solid Isotropic Material Penalization (SIMP) method. Finally, the optimized customized implant is fabricated in an additive manufacturing (AM) system. A case study of a craniofacial implant is presented and the results reveal that the proposed methodology is an effective approach to design and optimize craniofacial implants.

Simulation of Three-Dimensional Stress Distribution in Compression Dies

2008 ◽  
Vol 575-578 ◽  
pp. 449-454
Author(s):  
Chu Yun Huang ◽  
Sai Yu Wang ◽  
Tao Yang ◽  
Xu Dong Yan
Keyword(s):  
Stress Distribution ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Distribution Model ◽  
Extrusion Dies ◽  
Maximum Value ◽  
Multiple Unit ◽  
Stress Freezing Method ◽  
Experimental Values ◽  
Aided Design

The stress fields of rectangular and T shape compression dies were simulated by three dimensional photo-elasticity of stress freezing method. The rules of stress distribution of σx, σy, σz on the surface of rectangular and T-shaped dies were discovered, and the rules were also found inside the dies. The results indicate that the stress distribution of rectangular die is similar to that of T shape die. Obvious stress concentration in corner of die hole was observed. σz rises from die hole to periphery until it achieves maximum value then it diminishes gradually, and σz between die hole and fix diameter zone is higher than it is in other position. At the same time, the equations of stress field of extrusion dies were obtained by curved surface fitting experimental values in every observed point with multiple-unit regression analysis method and orthogonal transforms. These works can provide stress distribution model for die computer aided design and make.

scholarly journals Chairside CAD/CAM Materials: Current Trends of Clinical Uses

Biology ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1170
Author(s):  
Giulio Marchesi ◽  
Alvise Camurri Piloni ◽  
Vanessa Nicolin ◽  
Gianluca Turco ◽  
Roberto Di Lenarda
Keyword(s):  
Clinical Outcome ◽  
Computer Aided Design ◽  
Fabrication Process ◽  
Computer Assisted ◽  
Current Trends ◽  
Computer Aided ◽  
Restorative Materials ◽  
Cad Cam ◽  
Aided Design

Restorative materials are experiencing an extensive upgrade thanks to the use of chairside Computer-aided design/computer-assisted manufacturing (CAD/CAM) restorations. Therefore, due to the variety offered in the market, choosing the best material could be puzzling for the practitioner. The clinical outcome of the restoration is influenced mainly by the material and its handling than by the fabrication process (i.e., CAD/CAM). Information on the restorative materials performances can be difficult to gather and compare. The aim of this article is to provide an overview of chairside CAD/CAM materials, their classification, and clinically relevant aspects that enable the reader to select the most appropriate material for predictable success.

Self-Screening of the polarized electric field in Wurtzite Gallium Nitride along [0001] direction

2021 ◽  
Author(s):  
Qiu-Ling Qiu ◽  
Shi-Xu Yang ◽  
Qian-Shu Wu ◽  
Cheng-Lang Li ◽  
Qi Zhang ◽  
...  
Keyword(s):  
Electric Field ◽  
Computer Aided Design ◽  
High Performance ◽  
High Electron Mobility Transistors ◽  
High Electron ◽  
Screening Effect ◽  
White Leds ◽  
Design And Optimization ◽  
Electron Mobility Transistors ◽  
Dimensional Electron Gas

Abstract The strong polarization effect of GaN-based materials is widely used in high-performance devices such as white-light-emitting diodes (white LEDs), high electron mobility transistors (HEMTs) and GaN Polarization SuperJunctions. However, the current researches on the polarization mechanism of GaN-based materials are not sufficient. In this paper, we studied the influence of polarization on electric field and energy band characteristics of Ga-face GaN bulk materials by using a combination of theoretical analysis and semiconductor technology computer-aided design (TCAD) simulation. The self-screening effect in Ga-face bulk GaN under ideal and non-ideal conditions is studied respectively. We believe that the formation of high-density two-dimensional electron gas (2DEG) in GaN is the accumulation of screening charges. So that, we also clarify the source and accumulation of the screening charges caused by the GaN self-screening effect in this paper and aim to guide the design and optimization of high-performance GaN-based devices.

3D PRINTING OF PHARMACEUTICALS – LEADING TREND IN PHARMACEUTICAL INDUSTRY AND FUTURE PERSPECTIVES

2020 ◽  
pp. 10-16
Author(s):  
SHANKHADIP NANDI
Keyword(s):  
Drug Delivery ◽  
Pharmaceutical Industry ◽  
3D Printing ◽  
Computer Aided Design ◽  
Release Kinetics ◽  
Research Work ◽  
Economic Benefits ◽  
Pharmaceutical Products ◽  
Dosage Forms ◽  
Fused Deposition

3D printing technology is a rapid prototyping process based on computer-aided design software that is proficient to construct solid objects with various geometrics by depositing numerous layers in a sequence. The major advantages of three-dimensional printing (3DP) technology over the traditional manufacturing of pharmaceuticals include the customization of medications with individually adjusted doses, on-demand tailored manufacturing, unprecedented flexibility in the design, manufacturing of complex and sophisticated solid dosage forms, and economic benefits. Recently, many researchers have been invested their efforts in applying 3DP technology to the pharmaceutical development of drug products and different drug delivery systems. Selective laser sintering, fused deposition modeling, semi-solid extrusion, stereolithography, etc., are the multiple 3DP technologies that can be established in several customized and programmable medicines. Sublingual, orodispersible, and fast-dissolving drug delivery formulations by 3DP technology have been already manufactured. Controlled-release formulations with different characteristics, doughnut-shaped multi-layered tablets with linear release kinetics, and drug-loaded tablets with modified-release characteristics are recently fabricated using 3DP. However, few 3DP methods produce uneven shapes of dosage forms and comparatively porous structures. Cost of transition, adaptation to the existing facility, achieving regulatory approval, etc., are the present challenges that can restrict the extensive application of 3DP technology to pharmaceutical products. Intense research work for modifying the 3DP methods is simultaneously sustained for by-passing the flaws and current limitations of this technology. 3DP technology can act as a convenient and potential tool for the pharmaceutical industry which will set a revolutionary manufacturing style in the near future to facilitate patient-centered health care.

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