Evaluation Of Dimensional Accuracy Research Articles

EVALUATION OF DIMENSIONAL ACCURACY AND DENSITY OF DENTAL STRUCTURES MANUFACTURED BY DIFFERENT TECHNOLOGIES

This study focuses on the fabrication and analysis of a total of 90 dental structures (metal parts of dental prostheses – coping, bridges) of 3 types made of cobalt-chromium alloy through different fabrication technologies which include casting, additive manufacturing by selective laser melting (SLM) and subtraction technology by CNC milling. The manufacturing accuracy analysis was carried out by comparing the nominal model and the actual model obtained by 3D scanning of the fabricated dental structures in GOM Inspect software. Density measurements were performed by helium-based gas pycnometry. The data obtained were statistically analysed and a statistically significant difference was confirmed between the subtraction and additive technology. Based on the available manufacturing technologies, materials and equipment used to fabricate the samples for this study, it can be concluded that dentures fabricated by 3D printing are more accurate than dental structures fabricated by milling or casting technology.

Correction to: Evaluation of dimensional accuracy and surface integrity of cylindrical array microelectrodes and cylindrical array microholes machined by EDM

Correction to: Evaluation of dimensional accuracy and surface integrity of cylindrical array microelectrodes and cylindrical array microholes machined by EDM

Numerical Simulation of Flow Behaviour of PLA and PLA-Copper during Fused Deposition Modeling Process

Fused deposition modeling (FDM) has been developed to adapt more application with a wide variety of material used, especially metal filled PLA filament. However, choosing wrong PLA-based filaments’ process parameters is a popular situation that causes great product’s dimensional error. This research is focused on studying the difference in the input velocity parameters between PLA and PLA-copper filament. This paper presents a numerical nozzle model and use finite element analysis method to investigate the melted filament fluid behavior. Flow parameters such as pressure, melting temperature range and velocity were discussed in detail. Experiments were then carried to determine optimal printing velocity range of the two filaments. Results show that the filament input velocity has great influence on flow parameters as this velocity changes, the flow parameters change as well. Finally, based on the evaluation of dimensional accuracy of printed samples, the optimal input velocity for each type of filament has been found, which are 2 – 3.5 mm/s for PLA and under 5 mm/s for PLA-copper.

Evaluation of dimensional accuracy and surface integrity of cylindrical array microelectrodes and cylindrical array microholes machined by EDM

Evaluation of dimensional accuracy and surface integrity of cylindrical array microelectrodes and cylindrical array microholes machined by EDM

Fabrication of Customized dental guide by stereolithography method and evaluation of dimensional accuracy with artificial neural networks

The present study was investigated the production dental guides by using additive manufacturing stereolithography (SLA) technology, and the dimensional aperture values of the dental guides for dental implant treatment using artificial intelligence technology. The aim of this study is to benefit from artificial neural networks (ANNs) to classify the results obtained from the new production freedom of SLA by changing the existing design concept of dental guides. In the study, the Three Dimensional (3D) anatomical model was designed by using Mimics programme the data obtained from the Cone Beam Computed Tomography (CBCT) images of the patient. Three different dental guide designs were performed using the 3-Matic programme for dental implant treatment on the obtained 3D anatomical model. Dental guide designs and mandible model were produced with a SLA 3D printer, and a data set was created using a 3D scanner. The dimensional aperture values were obtained by performing the 3D registration process between the mandible and dental guides. The data set was analyzed both statistically with Jamovi 2.0.0 software and ANNs. The results showed that the minimum and maximum aperture values obtained from the dental guides were very close to each other, indicating that the guides were compatible with the mandible bone. The statistical results showed that the dimensional aperture values decrease in proportion to the values with minimum arithmetic mean value in the data set, and it was determined that the dental guide-3 was the most suitable model for the mandible. When all test data in the confusion matrix obtained from ten different aritificial neural network models created using ANNs were examined, it was been seen that ANN model-5 was the most successful model with an accuracy rate of 99%.

A Comparative Evaluation of Dimensional Accuracy and Surface Detail Reproduction for Polyvinyl Siloxane and Vinyl Siloxane Ether under Dry and Moist Conditions- An In-vitro Study

Introduction: The conventional impression procedure plays a major role in prosthodontics inspite of advancement in intra- oral scanning devices and 3D imaging procedures. Dimensional accuracy and surface detail reproduction are important for recording an impression. Aim: The study evaluated and compared the dimensional accuracy and surface detail reproduction of Polyvinyl Siloxane (PVS) and vinyl siloxane ether impression materials when used under dry and moist conditions. Materials and Methods: An in-vitro study was conducted in the Department of Prosthodontics, Rural Dental College, Pravara Institute of Medical Sciences, Loni, Ahmednagar, Maharashtra, India, for a period of two years from October 2018 to September 2020. A total of 60 impressions were made with PVS (Group A) and vinyl siloxane ether (Group B) under dry (A1, B1) and moist (A2, B2) conditions of stainless steel dies which had lines engraved on superior surface of the die. Using a Harloc’s Tool maker’s microscope, dimensional accuracy was measured by comparing the width of line Y in each impression. Surface detail reproduction was evaluated by American Dental Association (ADA) specification no. 19 where it stated continuous replication of at least any two lines out of the three lines inscribed on the die. Data analysis processing was performed in the SYSTAT version 12 (made by Crane’s software, Bangalore). Student’s unpaired t-test and Chi-square test were performed to determine statistical difference between PVS and vinyl siloxane ether where the level of significance was set at 5% and 1%. Results: The mean dimensional change and SD values for PVS under dry condition ranged from 21.93±2.46 to 22.40±2.89 (in mm). The mean dimensional change and SD values for PVS under moist condition ranged from 22.87±3.20 to 23.33±3.42. The mean dimensional change and SD values for vinyl siloxane ether under dry condition ranged from 21.93±3.61 to 24.73±5.20. The mean dimensional change and SD values for vinyl siloxane ether under moist condition ranged from 21.93±4.48 to 22.87±4.15. No statistical difference was found under dry and moist conditions within 2 hours and after 24 hours for both the materials. Conclusion: The study revealed no significant difference between dimensional accuracy and surface detail reproduction for PVS and vinyl siloxane ether. Both the materials can reproduce the details under dry and moist conditions satisfactorily and remained dimensionally stable till 24 hours after impression making.

Evaluation of dimensional accuracy and degree of polymerization of stereolithography photopolymer resin under different postpolymerization conditions: An in vitro study

Statement of problemThe appropriate postpolymerization of stereolithography (SLA) resins with the least effect on dimensional accuracy and with optimal polymerization is unclear. PurposeThe purpose of this in vitro study was to investigate the dimensional accuracy and degree of polymerization of a photopolymer resin for SLA with different postpolymerizing times and temperatures. Material and methodsSixty 1.5-mm-thick specimens were made from clear photopolymer resin with a 3D printer to simulate a maxillary complete denture. They were postpolymerized for different periods (15 and 30 minutes) at 3 different temperatures (40 °C, 60 °C, and 80 °C). Both prepolymerization and postpolymerization gap sizes for each specimen were measured at 5 different locations under a stereomicroscope. The tissue surface was scanned before and after polymerization, and the images were superimposed. The deviation was analyzed by using computer-aided design (CAD) software; root mean square estimates (RMSE) and color map data were obtained. Fourier transform infrared spectrometry was used to determine the degree of conversion (DC) of all specimens. The Kruskal-Wallis and Mann-Whitney tests were used to calculate the difference value of the gap sizes (α=.05). One-way ANOVA and the Tukey test were used for RMSE and DC (α=.05). ResultsThe smallest average change in gap sizes was found at 15 minutes and 40 °C, and the largest change at 30 minutes and 80 °C. The lowest RMSE was obtained at 30 minutes and 40 °C (P<.05). On the color map, a uniform deposited layer was created at 15 minutes and 40 °C and 30 minutes and 40 °C. The highest DC was found at 30 minutes and 60 °C, which differed significantly from 15 minutes and 40 °C (P<.05). The lowest degree of polymerization was found at 30 minutes and 40 °C. ConclusionsThe polymerizing temperature exerted a greater effect than polymerizing time, with lower temperatures leading to improved fit and tissue surface accuracy. The recommended parameters for SLA polymerization are 15 minutes and 40 °C. These conditions offered high dimensional accuracy, favorable surface tissue adaptation, and satisfactory DC.

Evaluation of dimensional accuracy and mechanical behavior of 3D printed reinforced polyamide parts

This paper aims to evaluate the mechanical behavior, dimensional accuracy and total cost of fused deposition modeling (FDM) produced reinforced polyamide (RPA) parts; glass reinforced PA and Kevlar reinforced PA. First of all, the standard specimens are printed by varying three parameters, namely the layer thickness, the print speed and the extrusion temperature. Then, the weight and main dimensions of the obtained samples are measured before the mechanical characterization by tensile test. The results showed the effect of extrusion temperature and layer thickness on material properties is more significant than the impact of print speed. The influence of evaluated factors on the dimensional accuracy and total cost is also observed. Overall, this experimental investigation showed the advantage of reinforcement in enhancing mechanical performance (tensile and fatigue properties) and lead to improving the knowledge about geometrical tolerance of FDM printed reinforced polymer components.

Evaluation of dimensional accuracy and material properties of the MakerBot 3D desktop printer

Purpose – This paper aims to evaluate the material properties and dimensional accuracy of a MakerBot Replicator 2 desktop 3D printer. Design/methodology/approach – A design of experiments (DOE) test protocol was applied to determine the effect of the following variables on the material properties of 3D printed part: layer height, per cent infill and print orientation using a MakerBot Replicator 2 printer. Classical laminate plate theory was used to compare results from the DOE experiments with theoretically predicted elastic moduli for the tensile samples. Dimensional accuracy of test samples was also investigated. Findings – DOE results suggest that per cent infill has a significant effect on the longitudinal elastic modulus and ultimate strength of the test specimens, whereas print orientation and layer thickness fail to achieve significance. Dimensional analysis of test specimens shows that the test specimen varied significantly (p &lt; 0.05) from the nominal print dimensions. Practical implications – Although desktop 3D printers are an attractive manufacturing option to quickly produce functional components, this study suggests that users must be aware of this manufacturing process’ inherent limitations, especially for components requiring high geometric tolerance or specific material properties. Therefore, higher quality 3D printers and more detailed investigation into the MakerBot MakerWare printing settings are recommended if consistent material properties or geometries are required. Originality/value – Three-dimensional (3D) printing is a rapidly expanding manufacturing method. Initially, 3D printing was used for prototyping, but now this method is being used to create functional final products. In recent years, desktop 3D printers have become commercially available to academics and hobbyists as a means of rapid component manufacturing. Although these desktop printers are able to facilitate reduced manufacturing times, material costs and labor costs, relatively little literature exists to quantify the physical properties of the printed material as well as the dimensional consistency of the printing processes.

Evaluation of Different Internal Structure and Build Orientation for Multijet Modeling Process

Rapid Prototyping (RP) technology has proven its capability to produce complex parts with shorter lead time. This advantage could benefit tremendously in application such as the Investment Casting (IC) process. The focus of the study is the production of sacrificial IC patterns produced using Multijet Modeling (MJM) RP technology. It includes the evaluation of dimensional accuracy and the surface roughness of part with a hollow and quasi hollow inner support patterns. Different internal structure's pattern were developed using CAD software, and the part were fabricated using MJM technique in two different build orientations. Analyses were done using Coordinate Measuring Machine (CMM) and the surface roughness tester. Results show that part built with 90º orientation is better than part built with 0º orientation both in terms of accuracies and roughness. Different internal structure similarly affects the final part quality, though the post processing steps also have their influence, thus making it no clear different among the parts. However, it demonstrated parts with square structure produced the best dimensional accuracy and the part with hatch structure produced the best surface roughness.

On the evaluation of dimensional accuracy in rotary stretch bending

The main objective of this work is to quantify the impact of the most important parameters on dimensional accuracy in stretch forming, combining analytical models and experiments conducted in industry-like stretch forming operations. Using the deformation theory of plasticity, an analytical moment-curvature model for prediction of deformations of a curved flange under the action of longitudinal stretching and transversal (local) bending was established. By combining suitable equilibrium and compatibility equations, the model was used for prediction of cross-sectional distortions. The overall results formed the basis for the development of a closed-form relationship for prediction of cross-sectional distortions. This model explicitly expresses the most important influential parameters and their impact on cross-sectional distortions. The results show that anisotropy, as represented by a Hill (1948) relationship, is the most important material characteristic with regard to suck-in of individual cross-sectional members. The strain hardening characteristic and the initial yield stress level of the material have very limited impact on local distortions. Moreover, geometrical parameters such as flange width, flange thickness, cross sectional height and web depth, play an important role with regard to dimensional accuracy. The analytical model also shows that the flange width is the single most important design parameter with regard to the nominal value of the flange’s suck-in, whereas the flange thickness is the main source to variability, i.e. noise parameter. The analytical results show remarkably good correlation with experimental results obtained in a full-scale rotary stretch forming setup.

Design, development and evaluation of 3D mold inserts using a rapid prototyping technique and powder-sintering process

In this research work, attempts have been made to design, develop and evaluate the performance of mould inserts for injection moulding by using a powder-sintering process. Maraging steel powder, sintering aid and binder are materials used in this proposed development process. Attempts have been made to perform in-depth studies and to apply the powder-sintering process, to eventually produce the final sintered components. In addition, an analysis of the dimensional accuracy of the respective stereolithography master models and an analysis of the sintered specimens during various stages of powder-sintering process have been carried out. The intelligent manufacturing systems (IMS) test part with minor modifications has been used in the evaluation of dimensional accuracy, tolerances, distortion and volumetric variations. The main reason for using this unique geometry is the suitability of its design for injection-moulding processes and tooling.