scholarly journals Dimensional Accuracy of Stone Casts Obtained with Multiple Pours into the Same Mold

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Valdimar da Silva Valente ◽  
Artêmio Luiz Zanetti ◽  
Pedro Paulo Feltrin ◽  
Ricardo Tatsuo Inoue ◽  
Carmem Dolores Vilarinho Soares de Moura ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Coordinate Measuring Machine ◽  
Dimensional Accuracy ◽  
Wait Time ◽  
Type Iv ◽  
Impression Technique ◽  
Fixed Prosthesis ◽  
Measuring Machine ◽  
Master Model ◽  
Made In

Aim. The aim of the present study was to compare the dimensional accuracy of stone casts obtained with vinyl polysiloxane molds through the double-impression technique with three pours into the same mold. Methods. A stainless steel master model was constructed simulating a three-unit fixed prosthesis. Twelve impressions were taken of this master model with addition silicone, using the double-impression technique. Three pours of type IV gypsum were then made into each mold, thus producing 36 casts. The pours were made 1 hour, 6 hours and 24 hours after the impression procedure. Next, intra- and interabutment measurements were made in a coordinate measuring machine. Results. Comparative analysis of the dimensional accuracy of stone casts resulting from multiple pours was not statistically significant in pours first and second (P>0.05). These values, however, were statistically significant at third pour in the height in abutment 1 and upper distance interabutment. Conclusion. The wait time (1 hour, and 6 hours) observed before pouring the stone into the same molds did not cause significant dimensional accuracy of the casts.

scholarly journals Measurement of the accuracy of dental working casts using a coordinate measuring machine

2016 ◽  
Vol 73 (10) ◽  
pp. 895-903 ◽  
Author(s):  
Michal Potran ◽  
Branko Strbac ◽  
Tatjana Puskar ◽  
Miodrag Hadzistevic ◽  
Janko Hodolic ◽  
...  
Keyword(s):  
Coordinate Measuring Machine ◽  
Impression Material ◽  
Type Iv ◽  
Impression Accuracy ◽  
Dental Impression ◽  
Abutment Teeth ◽  
Measuring Machine ◽  
Master Model ◽  
Degree Of Convergence

Background/Aim: Dental impressions present a negative imprint of intraoral tissues of a patient which is, by pouring in gypsum, transferred extraorally on the working cast. Casting an accurate and precise working cast presents the first and very important step, since each of the following stages contributes to the overall error of the production process, which can lead to inadequately fitting dental restorations. The aim of this study was to promote and test a new model and technique for in vitro evaluation of the dental impression accuracy, as well as to asses the dimensional stability of impression material depending on the material bulk, and its effect on the accuracy of working casts. Methods. Impressions were made by the monophasic technique using the experimental master model. Custom trays with spacing of 1, 2 and 3 mm were constructed by rapid prototyping. The overall of 10 impressions were made with each custom tray. Working casts were made with gypsum type IV. Measurement of working casts was done 24 h later using a co-ordinate measuring machine. Results. The obtained results show that the working casts of all the three custom trays were in most cases significantly different in the transversal and sagittal planes in relation to the master model. The height of abutments was mainly unaffected. The degree of convergence showed certain significance in all the three custom trays, most pronounced in the tray with 3 mm spacing. Conclusion. The impression material bulk of 1?3 mm could provide accurate working casts when using the monophasic impression technique. The increase of the distance between abutment teeth influences the accuracy of working casts depending on the material bulk.

Three-Dimensional Accuracy of Implant and Abutment Level Impression Techniques: Effect on Marginal Discrepancy

2011 ◽  
Vol 37 (6) ◽  
pp. 649-657 ◽  
Author(s):  
Marzieh Alikhasi ◽  
Hakimeh Siadat ◽  
Abbas Monzavi ◽  
Fatemeh Momen-Heravi
Keyword(s):  
Angular Displacement ◽  
Angular Position ◽  
Three Dimensional ◽  
Coordinate Measuring Machine ◽  
Dimensional Accuracy ◽  
Acrylic Resin ◽  
Positional Accuracy ◽  
Type Iv ◽  
Marginal Discrepancy ◽  
Measuring Machine

Impression techniques should precisely represent the 3-dimensional status of implants to allow for the fabrication of passively fitting prostheses and subsequently the elimination of strain on supporting implant components and surrounding bone. The aim of this study was to compare the accuracy of an abutment level impression method with that of an implant level (direct and indirect) impression method using polyether impression material to obtain precise definitive casts and prostheses. A reference acrylic resin dentoform with 2 internal connection implants (Implantium) was made. A total of 21 medium-consistency polyether impressions of the dentoform, including 7 direct implant level, 7 indirect implant level, and 7 abutment level (after 2 straight abutments were secured), were made. Impressions were poured with American Dental Association (ADA) type IV stone, and the positional accuracy of the implant replica heads and abutment analogs in each dimension of x-, y-, and z-axes, as well as angular displacement (Δθ), was evaluated using a coordinate measuring machine. Noble alloy 3-unit castings were fabricated and seated on the abutments in 3 groups; marginal discrepancies were measured at 4 points between prostheses and abutments. Data were analyzed using Mann-Whitney U test, 1-way analysis of variance (ANOVA), and Kruskal-Wallis tests. In comparisons of different impression techniques, only significant statistical Δθ differences were noted between the abutment level method and other techniques (P < .001). Results of this study reveal that although the implant level impression method could better transfer the angular position of the implants (Δθ), the impression method could not affect Δy, Δx, and Δz coordinates of the implants or marginal discrepancy of the 3-unit fixed partial dentures (FPD).

scholarly journals Evaluation of dimensional accuracy of dental bridges manufactured with conventional casting technique and CAD/CAM system with Ceramill Sintron blocks using CMM

2018 ◽  
Vol 12 (4) ◽  
pp. 264-271 ◽  
Author(s):  
Alireza Izadi ◽  
Fariborz Vafaee ◽  
Arash Shishehian ◽  
Ghodratollah Roshanaei ◽  
Behzad Fathi Afkari
Keyword(s):  
Reference Model ◽  
Coordinate Measuring Machine ◽  
Dimensional Accuracy ◽  
Three Dimensions ◽  
Casting Technique ◽  
Dimensional Changes ◽  
Conventional Casting ◽  
Cad Cam ◽  
Milling Method ◽  
Measuring Machine

Background. Recently, non-presintered chromium-cobalt (Cr-Co) blocks with the commercial name of Ceramill Sintron were introduced to the market. However, comprehensive studies on the dimensional accuracy and fit of multi-unit frameworks made of these blocks using the coordinate measuring machine (CMM) are lacking. This study aimed to assess and compare the dimensional changes and fit of conventional casting and milled frameworks using Ceramill Sintron. Methods. A metal model was designed and scanned and 5-unit frameworks were fabricated using two techniques: (I) the conventional casting method (n=20): the wax model was designed, milled in the CAD/CAM machine, flasked and invested; (II) the milling method using Ceramill Sintron blocks (n=20): the wax patterns of group 1 were used; Ceramill Sintron blocks were milled and sintered. Measurements were made on the original reference model and the fabricated frameworks using the CMM in all the three spatial dimensions, and dimensional changes were recorded in a checklist. Data were analyzed with descriptive statistics, and the two groups were compared using one-way ANOVA and Tukey test (α=0.05). Results. The fabricated frameworks in both groups showed significant dimensional changes in all the three dimensions. Comparison of dimensional changes between the two groups revealed no significant differences (P>0.05) except for transverse changes (arch) that were significantly greater in Ceramill Sintron frameworks (P<0.05). Conclusion. The two manufacturing processes were the same regarding dimensional changes and the magnitude of marginal gaps and both processes resulted in significant dimensional changes in frameworks. Ceramill Sintron frameworks showed significantly greater transverse changes than the conventional frameworks.

Experimental Investigations for Rapid Moulding Solution of Plastics Using Polyjet Printing

2011 ◽  
Vol 701 ◽  
pp. 15-20 ◽  
Author(s):  
Rupinder Singh ◽  
Varinderjit Singh
Keyword(s):  
Plastic Material ◽  
Coordinate Measuring Machine ◽  
Dimensional Accuracy ◽  
Point Of View ◽  
Experimental Investigations ◽  
Support Material ◽  
Economic Point ◽  
Measuring Machine ◽  
Plastic Components ◽  
Polyjet Printing

Rapid prototyping (RP) has been in evidence for the past twenty years and is being widely used in diverse areas, from the building of aesthetic and functional prototypes to the production of tools and moulds for technological prototypes. The purpose of the present study is to experimentally investigate the rapid moulding (RM) solutions for plastic components using polyjet printing (PP) technique. Starting from the identification of component/benchmark, prototypes with three different type of plastic material were produced, at different orientation and support material. Measurements on the coordinate measuring machine helped in calculating the dimensional tolerances of the plastic components produced. Some important mechanical properties were also compared to verify the suitability of the components. The study highlighted the best orientation, support material quantity and type of plastic material for the selected component from dimensional accuracy and economic point of view as RM solution for plastic components. This process ensures rapid production of pre-series technological prototypes and proof of concept at less production cost and time.

On-Machine Inspecting

2005 ◽  
Vol 127 (04) ◽  
pp. 30-33 ◽  
Author(s):  
Paul Sharke
Keyword(s):  
Stainless Steel ◽  
Coordinate Measuring Machine ◽  
Machine Shop ◽  
Colorado Springs ◽  
Complex Curves ◽  
Measuring Machine ◽  
One Machine

This article discusses about on-machine inspecting. This type of inspecting has helped to turn around business for at least one machine shop, Tech Machine in Colorado Springs, Colo., where it is made a big dent in scrap rates. Tech Machine manufactures tight-tolerance stainless steel and titanium medical parts that have many complex curves and very smooth finishes. On-machine inspecting has helped to turn around business for at least one machine shop, Tech Machine in Colorado Springs, Colo., where it is made a big dent in scrap rates. Tech Machine manufactures tight-tolerance stainless steel and titanium medical parts that have many complex curves and very smooth finishes. A part that can be measured at the machine and corrected there is one that avoids moving between the numerically controlled machine and the coordinate measuring machine. Small cuts can be made and then checked immediately.

scholarly journals Characterization of machining quality attributes based on spindle probe, coordinate measuring machine, and surface roughness data

2014 ◽  
Vol 1 (2) ◽  
pp. 128-139 ◽  
Author(s):  
Tzu-Liang Bill Tseng ◽  
Yongjin James Kwon
Keyword(s):  
Surface Roughness ◽  
Coordinate Measuring Machine ◽  
Dimensional Accuracy ◽  
Quality Characteristics ◽  
Machining Parameters ◽  
Production Environment ◽  
Significant Interaction Effect ◽  
Machining Quality ◽  
Measuring Machine ◽  
Touch Probe

Abstract This study investigates the effects of machining parameters as they relate to the quality characteristics of machined features. Two most important quality characteristics are set as the dimensional accuracy and the surface roughness. Before any newly acquired machine tool is put to use for production, it is important to test the machine in a systematic way to find out how different parameter settings affect machining quality. The empirical verification was made by conducting a Design of Experiment (DOE) with 3 levels and 3 factors on a state-of-the-art Cincinnati Hawk Arrow 750 Vertical Machining Center (VMC). Data analysis revealed that the significant factor was the Hardness of the material and the significant interaction effect was the Hardness + Feed for dimensional accuracy, while the significant factor was Speed for surface roughness. Since the equally important thing is the capability of the instruments from which the quality characteristics are being measured, a comparison was made between the VMC touch probe readings and the measurements from a Mitutoyo coordinate measuring machine (CMM) on bore diameters. A machine mounted touch probe has gained a wide acceptance in recent years, as it is more suitable for the modern manufacturing environment. The data vindicated that the VMC touch probe has the capability that is suitable for the production environment. The test results can be incorporated in the process plan to help maintain the machining quality in the subsequent runs.

Experimental Investigations for Statistically Controlled Rapid Moulding Solution of Plastics Using Polyjet Printing

2010 ◽  
Author(s):  
Rupinder Singh ◽  
Varinderjit Singh ◽  
Manohar Singh Saini
Keyword(s):  
Plastic Material ◽  
Coordinate Measuring Machine ◽  
Dimensional Accuracy ◽  
Point Of View ◽  
Experimental Investigations ◽  
Economic Point ◽  
The Past ◽  
Measuring Machine ◽  
Plastic Components ◽  
Polyjet Printing

Rapid prototyping (RP) has been in evidence for the past twenty years and is being widely used in diverse areas, from the building of aesthetic and functional prototypes to the production of tools and moulds for technological prototypes. The purpose of the present study is to experimentally investigate statistically controlled rapid moulding (RM) solutions for plastic components using polyjet printing (PP). Starting from the identification of component/benchmark, prototypes with three different type of plastic material were prepared, at different orientations. Measurements on the coordinate measuring machine helped in calculating the dimensional tolerances of the components prepared. Some important mechanical properties were also compared to verify the suitability of the components. The study highlighted the best orientation, support material quantity and type of plastic material for the selected component from dimensional accuracy and economic point of view as RM solution for plastic components. Final components prepared are acceptable as per ISO standard UNI EN 20286-I (1995). This process ensures rapid production of statistically controlled pre-series technological prototypes and proof of concept at less production cost and time.

Dimensional Tolerance of Casting in the Bridgman Furnace Based on 3D Printing Techniques

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 299
Author(s):  
Xintao Zhu ◽  
Fu Wang ◽  
Dexin Ma ◽  
Andreas Bührig-Polaczek
Keyword(s):  
3D Printing ◽  
Investment Casting ◽  
Systematic Approach ◽  
Low Cost ◽  
Coordinate Measuring Machine ◽  
Dimensional Accuracy ◽  
Metal Casting ◽  
Measuring Machine ◽  
Printing Techniques ◽  
Short Times

In this article, the feasibility and the dimensional accuracy based on the 3D printing technology during investment casting of non-vacuum and Bridgman furnace are investigated based on the coordinate measuring machine to calculate the dimensional tolerances through a systematic approach. The research proved that both the investigated RC solutions are effective at obtaining cast technological prototypes in short times and at low cost, with dimensional tolerances that are completely consistent with metal casting processes.

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

2013 ◽  
Vol 315 ◽  
pp. 587-591 ◽  
Author(s):  
M.N. Hafsa ◽  
M. Ibrahim ◽  
S. Sharif ◽  
M.F.M. Omar ◽  
M.A. Zainol
Keyword(s):  
Surface Roughness ◽  
Internal Structure ◽  
Coordinate Measuring Machine ◽  
Dimensional Accuracy ◽  
Part Quality ◽  
Modeling Process ◽  
Measuring Machine ◽  
Complex Parts ◽  
Processing Steps ◽  
Better Than

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.

A Study on the Shrinkage Characteristics and Dimensional Accuracy of Cast Gears

1992 ◽  
Author(s):  
Jimmy Adjunta ◽  
Donald Houser
Keyword(s):  
Investment Casting ◽  
Coordinate Measuring Machine ◽  
Dimensional Accuracy ◽  
Machining Process ◽  
Spur Gears ◽  
Design Phase ◽  
Process Variables ◽  
Measuring Machine ◽  
Thickness Measurements

Abstract This paper is primarily concerned with the evaluation of the dimensional quality of spur gears produced by two casting processes, i. e., the investment casting and v-sand casting processes. The casting patterns used were designed by compensating for process shrinkage, and were manufactured using a flexible CNC gear machining process. A computer program, CASTGR, was written to facilitate the design phase of the patterns. The various gear configurations cast were inspected using an universal coordinate measuring machine. The geometry of the casting and pattern were correlated to verify the contraction characteristics of the gear castings. In an attempt to categorize the precision capabilities of the two casting processes, the spread of the deviations found for tooth thickness measurements and measurements along profiles and leads of the cast gears were examined. The observed effects of other process variables is also included.

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