Algorithms for Nesting of Ship/Offshore Structural Plates

17th Design Automation Conference: Volume 2 — Computer-Aided Design, Mechanical Systems Simulation, and Analysis, Mechanisms, and Robotics ◽

10.1115/detc1991-0122 ◽

1991 ◽

Author(s):

B. T. Cheok ◽

A. Y. C. Nee

Keyword(s):

Feature Extraction ◽

Search Time ◽

Computer Search ◽

Rectangle Packing ◽

Manual Method ◽

Input And Output ◽

Material Usage ◽

Shape Processing ◽

Cad Cam ◽

Cam Systems

Abstract This paper discusses the development of a set of algorithms for the automatic nesting of ship/offshore structural plates. The algorithms are developed to take advantage of the peculiarity of most ship/offshore structural plates with the aims of optimising material usage and minimising computer search time. The parts to be nested are first processed by a shape processing routine which employs a simple feature extraction approach to classify the plates according to predefined rules specially adopted for ship/offshore structural shapes. The most appropriate search path for each class of plates is used to obtain the best enclosing rectangle for similar shapes. The search paths are based on heuristics developed to simulate the manual method used by the human operator. Finally, all the plates are laid out on the stock sheet using a “rectangle packing” approach. A computer package, Patnest-Ship was developed to demonstrate the efficiency of the algorithms and very encouraging results are achieved. The input and output files to and from Patnest-Ship are described in DXF format so that it can be integrated with existing CAD/CAM systems. Pre- and post-processors for this package have been implemented on AutoCAD to permit the user to define the plates and interactively improve on the solutions provided by Patnest-Ship, if necessary.

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ANALYSIS OF THE PRICE OF THE MANUFACTURE OF BATCH PARTS FOR CNC MILLING AUXILIATED BY CAD / CAM SYSTEMS

10.26678/abcm.conem2018.con18-1134 ◽

2018 ◽

Author(s):

ERIC RAMALHO FERREIRA DE CARVALHO ◽

MARCOS VINICYUS OLIVEIRA ◽

erijanio Silva ◽

Gutembergy Diniz ◽

João Dehon Rocha Junior ◽

...

Keyword(s):

Cnc Milling ◽

Cad Cam ◽

Cam Systems

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Marginal and Internal Fit of Ceramic Prostheses Fabricated from Different Chairside CAD/CAM Systems: An In Vitro Study

Applied Sciences ◽

10.3390/app11020857 ◽

2021 ◽

Vol 11 (2) ◽

pp. 857

Author(s):

Keunbada Son ◽

Kyu-Bok Lee

Keyword(s):

Computer Aided Design ◽

In Vitro Study ◽

Vitro Study ◽

Marginal Gap ◽

Significant Difference ◽

Cad Cam ◽

Ceramic Crowns ◽

Internal Fit ◽

Cam Systems

The purpose of this in vitro study was to evaluate marginal and internal fits of ceramic crowns fabricated with chairside computer-aided design and manufacturing (CAD/CAM) systems. An experimental model based on ISO 12836:2015 was digitally scanned with different intraoral scanners (Omnicam (CEREC), EZIS PO (DDS), and CS3500 (Carestream)). Ceramic crowns were fabricated using the CAD/CAM process recommended by each system (CEREC, EZIS, and Carestream systems; N = 15). The 3-dimensional (3D) marginal and internal fit of each ceramic crown was measured using a 3D inspection software (Geomagic control X). Differences among the systems and various measurements were evaluated using the Kruskal–Wallis test. Statistically significant differences were validated using pairwise comparisons (α = 0.05). Occlusal gaps in the CEREC, EZIS, and Carestream groups were 113.0, 161.3, and 438.2 µm, respectively (p < 0.001). The axial gaps were 83.4, 78.0, and 107.9 µm, respectively. The marginal gaps were 77.8, 99.3, and 60.6 µm, respectively, and the whole gaps were 85.9, 107.3, and 214.0 µm, respectively. Significant differences were observed with the EZIS system compared with the other two systems in terms of the marginal gap sizes. The CEREC system showed no significant differences among the four measured regions. However, the EZIS and Carestream systems did show a statistically significant difference (p < 0.05). All three systems were judged to be capable of fabricating clinically acceptable prostheses, because the marginal gap, which is the most important factor in the marginal fit of prostheses, was recorded to be below 100 µm in all three systems.

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Machining Feature-Based CAD/CAPP for STEP-NC

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.598.591 ◽

2014 ◽

Vol 598 ◽

pp. 591-594 ◽

Cited By ~ 2

Author(s):

Li Yan Zhang

Keyword(s):

Process Planning ◽

Manufacturing Process ◽

Data Transfer ◽

Operation Planning ◽

Computer Aided Process Planning ◽

Machining Feature ◽

Computer Aided ◽

Cad Cam ◽

Feature Based ◽

Cam Systems

ISO 14649, known as STEP-NC, is new model of data transfer between CAD/CAM systems and CNC machines. In this paper, the modeling based on machining feature is proposed. The machining feature comes from the manufacturing process considering the restriction of machining technology and machining resource. Then the framework for computer aided process planning is presented, where the algorithms of operation planning is studied. The practical example has been provided and results indicate that machining feature based model can integrate with CAPP and STEP-NC seamlessly.

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Marginal fit of all-ceramic crowns fabricated using two extraoral CAD/CAM systems in comparison with the conventional technique

Clinical Cosmetic and Investigational Dentistry ◽

10.2147/ccide.s130856 ◽

2017 ◽

Vol Volume 9 ◽

pp. 13-18 ◽

Cited By ~ 11

Author(s):

Fawaz Alqahtani

Keyword(s):

Conventional Technique ◽

Marginal Fit ◽

All Ceramic ◽

Cad Cam ◽

Ceramic Crowns ◽

Cam Systems

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Effect of Particle Size of ZrO2(Y2O3) Powders on the Shrinkage of the Sintered Substrate with Coloring Gradient

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.87.162 ◽

2014 ◽

Vol 87 ◽

pp. 162-168

Author(s):

Paula Cipriano da Silva ◽

Roberto de Oliveira Magnago ◽

Camila Aparecida Araujo da Silva ◽

Bianca de Almeida Fortes ◽

Claudinei dos Santos

Keyword(s):

White Layer ◽

Linear Shrinkage ◽

Particle Sizes ◽

X Ray Diffraction ◽

X Ray ◽

Particles Size Distribution ◽

Cad Cam ◽

Effect Of Particle Size ◽

Cam Systems ◽

Zirconia Powders

ZrO2(Y2O3)-based ceramics with coloring gradient can facilitate the development of dental prosthesis by the improvement of esthetic properties. In this work, ZrO2 powders with different particle sizes were investigated. White and yellow zirconia powders (TOSOH Corporation-Japan) were characterized by particles size distribution using nanoSight-LM20 analyzer. Furthermore, samples were characterized by X-Ray diffraction, Scanning Electron Microscopy and relative density. Compacts with two layers, one white and one yellow were uniaxially pressed at 80MPa and sintered at 1530°C-120min. The yellow-powder presented average particles size of 180±66nm, while the white-powder presented particles size of 198±73nm. After sintering, full dense ceramics with tetragonal phase were obtained. The linear shrinkage of the yellow and white-layer was 22.75% and 22.05% respectively. This difference in shrinkage is important in the machining of prostheses in ceramic CAD/CAM systems, because they lead to difficulties in adapting this customized prosthesis in patients.

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Knowledge Based Expert Systems for CAD/CAM Experience of an EDM Application

13th Computers in Engineering Conference ◽

10.1115/cie1993-0035 ◽

1993 ◽

Author(s):

D. Kiritsis ◽

Michel Porchet ◽

L. Boutzev ◽

I. Zic ◽

P. Sourdin

Keyword(s):

Natural Language ◽

System Development ◽

Constraint Propagation ◽

Programming Environment ◽

Knowledge Based ◽

Natural Language Programming ◽

Cad Cam ◽

The One ◽

Rule System ◽

Cam Systems

Abstract In this paper we present our experience from the use of two different expert system development environments to Wire-EDM CAD/CAM knowledge based application. The two systems used follow two different AI approaches: the one is based on the constraint propagation theory and provides a natural language oriented programming environment, while the other is a production rule system with backward-forward chaining mechanisms and a conventional-like programming style. Our experience showed that the natural language programming style offers an easier and more productive environment for knowledge based CAD/CAM systems development.

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Vertical and Horizontal Misfit Analysis of 3-unit FDP Fabricated with Different Techniques and CAD/CAM Systems

Brazilian Dental Journal ◽

10.1590/0103-6440201801916 ◽

2018 ◽

Vol 29 (4) ◽

pp. 342-346

Author(s):

Eduardo Piza Pellizzer1 ◽

Caroline Cantieri de Mello ◽

Jéssica Marcela de Luna Gomes ◽

Joel Ferreira Santiago Júnior ◽

Cleidiel Aparecido Araújo Lemos ◽

...

Keyword(s):

Reference Model ◽

Optical Microscope ◽

The Other ◽

Marginal Adaptation ◽

Nicr Alloy ◽

Partial Denture ◽

Optical Scanning ◽

Fixed Partial Denture ◽

Cad Cam ◽

Cam Systems

Abstract The aim of this is was evaluate the vertical and horizontal marginal adaptation of 3-unit fixed partial denture frameworks fabricated using different techniques and CAD/CAM systems. A total of 40 framework specimens were fabricated and divided into four groups as follows: lost-wax casting (G1); lost-wax casting with welding (G2); extraoral optical scanning of models (3S/DWOS) (G3); intraoral optical scanning (Cerec Bluecam/Sirona) (G4). A reference model was used to simulate a fixed partial denture with three elements (with a central pontic). The frameworks of G1 and G2 were cast in nickel-chromium (NiCr) alloy, whereas those of G3 and G4 were milled in zirconia. In all groups, vertical and horizontal marginal adaptation (over-contour and under-contour) was evaluated using a three-dimensional optical microscope (Quick Scope, Mitutoyo). The results showed higher vertical marginal misfit in G1 than in the other groups (p<0.001). Regarding horizontal marginal misfit, higher over-contour values occurred in G3 than in the other groups (p<0.001). G3 did not show under-contour at all, whereas the other groups did not differ from each other in this regard (p>0.05). Within the limitations of this study, it can be concluded that lost-wax casting with welding is a viable alternative to the use of CAD/CAM systems to fabricate frameworks of three-unit FPDs, since the techniques yielded similar vertical misfit values. Extra-oral CAD/CAM systems showed the highest horizontal misfit (over-contour) compared to other groups.

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