Analysis of Characteristics of Non-Commercial Software Systems for Assessing Flatness Error by Means of Minimum Zone Method

As far as machine parts are concerned, accuracy can be defined in many aspects. In order for a workpiece to be functional, dimensional and surface roughness requirements are not enough. Accuracy of geometric elements and position tolerances is necessary information. The notation, definitions, interpretations and general values of geometric tolerances are defined by standards. Nevertheless, there are several mathematical methods of calculating values based on data measured by means of coordinate measuring machines. Standards demand the use of the minimum zone method in assessing form deviation without mentioning the way of obtaining it. In this paper, the minimum zone method, which is an iterative algorithm, was investigated. Thus, the result of flatness measurement was calculated by continuous approximation. There are various methods of defining the steps of iteration, affecting the length of time and accuracy of the flatness value. The aim of the research was to examine the characteristics of two non-commercial software solutions for assessing the minimum zone in comparison with the commercial CMM software. Based on the analysis, it can be concluded that the developed software solutions are efficient in assessing flatness error and that the differences between these and the commercial software are negligible

The Analysis of Metrological Characteristics of Different Coordinate Measuring Systems

The aim of this paper is to examine the metrological characteristics of some of the most commonly used coordinate measurement systems in industry in a case study of the flatness error. The accuracy and measurement uncertainty of the coordinate measuring machine with contact probe, point by point mode and scanning mode, and with non - contact probe, then performance measuring arm, optical scanner and finally industrial computed tomography were analyzed. In order to exclude factors that affect the accuracy of measurement and measurement uncertainty, and are not part of the hardware structure of the CMS, the experiment was conducted on a reference workpiece and an independent software solution was used to estimate the error of flatness. The accuracy of measuring systems was determined as the difference between the reference value and the mean value of repeated measurements and the measurement uncertainty was determined according to the instructions for estimating the measurement uncertainty GUM. The results of the research showed high metrological performance of the coordinate measuring machine and the optical scanner for this measuring task. Also, it was found that industrial computed tomography gives a very large measurement error and that the measurement uncertainty is very difficult to determine

Ispitivanje preciznosti radnih modela pomoću koordinatne merne mašine u stomatologiji

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 coordinate 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.Uvod/Cilj. Otisak predstavlja negativ intraoralnih tkiva, čijim se izlivanjem u gipsu njihova morfologija prenosi ekstraoralno na budući radni model. Sa laboratorijskog aspekta izrade zubnih nadoknada, izlivanje tačnog i preciznog radnog modela predstavlja prvi i veoma bitan korak, pošto svaka sledeća faza doprinosi daljem povećanju greške tokom izrade, što za krajnji ishod može imati neodgovarajuću zubnu nadoknadu. Cilj istraživanja bio je da se ispitaju novi model i tehnika za in vitro procenu preciznosti zubnih otisaka, kao i da se odredi uticaj količine otisnog materijala na dimenzionu stabilnost otisaka i preciznost izrade radnih modela. Metode. Za uzimanje otisaka korišćena je monofazna tehnika otiskivanja. Individualne kašike sa međuprostorom od 1, 2 i 3 mm napravljene su aditivnom tehnologijom za brzu izradu prototipova. Sa svakom kašikom napravljeno je po 10 otisaka. Radni modeli izlivani su u gipsu tipa IV. Merenje radnih modela vršeno je nakon 24 sata na koordinatnoj mernoj mašini. Rezultati. Rezultati pokazuju da radni modeli napravljeni pomoću sve tri individulane kašike u transverzalnoj i sagitalnoj ravni značajno odstupaju od glavnog dela modela. Visina patrljaka je u većini slučajeva bila kao na glavnom modelu. Stepen konvergencije pokazao je određena odstupanja samo kod kašike sa međuprostorom od 3 mm. Zaključak. Monofazna tehnika otiskivanja i otisni materijal debljine od 1 do 3 mm obezbeđuju izradu preciznih radnih modela. Rastojanje između zubnih patrljaka utiče na preciznost izrade radnih modela u zavisnosti od količine otisnog materijala

Advanced procedure for fabrication of substructure in dentistry

The paper presents some aspects of the novel integrated system, procedure for fabrication of metal substructure of metal-ceramic crowns. The results been shown that the CAD/CAE/RP technology integration presented in this paper can be fully applied to casting metal substructures. The substructure fabricated in this way, confirm the reduction of the total manufacturing time, with an increase in the percentage of high quality castings that use integrated system

Inteligentni robotski sistemi za ekstremno diverzifikovanu proizvodnju

U okviru ovog rada navode se rezultati sprovedenih istraživanja na četvorogodišnjem projektu TR35007 koji zajednički realizuju Mašinski fakultet Univerziteta u Beogradu, Fakultet tehničkih nauka Univerziteta u Novom Sadu i kompanija Ikarbus iz Beograda. Ovaj projekat finansijskih podržava Ministarstvo prosvete i nauke u okviru četovorogodišnjeg ciklusa istraživačkih projekata za tehnološki razvoj, od 2011. do 2014. godine. Prvo se navode istraživački okvir projekta, osnovni ciljevi koji postavljeni pred istraživački tim i organizacija projekta koja je izvedena po modelu radnih paketa. U drugom delu rada navode se osnovni rezultati ostvaranih u prvoj istraživačkoj godini, sa odgovarajućim opisom i osnovnim detaljima tehničke i organizacione prirode

NETWORKS AND QUALITY IMPROVEMENT

Tools used in the past to analyze business value creation, such as value chain and process models, are simply too slow, inadequate, or inappropriate to address this new level of business complexity. In stead of that, company has to find way to create quality management system in a multi-layered supply chain. The problem can be solved by networking in the cluster. Cluster can be known as a competitive cooperation in the purpose to gain higher level of competitiveness and success. Bat there is another problem: Organization of the production process in a company is extremely complex process itself, and when we transfer it to the cluster level, we get a complex task which is difficult to solve. For that purpose, this paper analyses the conditions and possibilities that would enable those structures to adapt to changes in the surroundings - flexibility and management adequacy of production and organizational structures - by creating network value system

Application of group technology in complex cluster type organizational systems

The aim of this research was to contribute to the development of structural design procedures of complex - cluster type organizational systems. Industrial clusters can help companies to improve their own market positions, effectiveness, productivity and product quality. Organization of the production process in a company is an extremely complex process itself, and when it is transferred to the cluster level, the result is a complex task which is difficult to solve. For that purpose, this paper analyses the conditions and possibilities that would enable those structures to adapt to changes in the surroundings - flexibility and management adequacy of production and organizational structures - by lowering the degree of complexity. For the time being, no simple models which would enable an increase of process effectiveness in complex organizational units like clusters have been developed. One of the possible solutions which would decrease the complexity of flows and increase process effectiveness within an industrial cluster is the application of Group approach

Comparative analysis of the results of measuring roundness

Coordinate measuring machines are devised for most complex measurements. Besides their dimension measuring abilities, the CNC operated machines can measure geometrical characteristics of form, such as straightness, roundness, cylindricity, etc. These are vital features in current times when control needs to submit very thorough reports not only on the form, but also on the geometrical features of the given workpiece. Yet the question arises: are these measuring data regarding roundness received from the CMM accurate and reliable enough for them to be exploited? In order to confirm this statement, the geometrical roundness characteristics are measured on three types of coordinate measuring machines, the results of which are analyzed from several aspects. The results have shown a special importance of specific measuring parameters and have shown to be independent of the type of measuring machines

Determination of Emissivity of Brass Alloy using Infrared Thermographic Technique

This paper presents the experimental determination of the dependence of emissivity of brass on surface roughness and temperature. The investigation was conducted using the infrared thermographic technique on brass alloy C27200 workpieces with different degrees of surface roughness, during the continuous cooling process. The results obtained showed that the emissivity of the chosen brass alloy increases with greater surface roughness and decreases during the cooling process, its value ranging from 0.07 to 0.19. It was concluded that surface roughness has a greater influence on the increase of the emissivity at higher temperatures, which can be seen in the three-dimensional infrared images. Multiple regression analysis confirmed a strong correlation between the examined parameters and the emissivity, and an original multiple regression model was determined