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Прегледај по Аутор "Kraišnik, Milija"

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ADDITIVE MANUFACTURING OF FUNCTIONAL PARTS BASED ON MATERIAL EXTRUSION TECHNOLOGY
(Akademija nauka i umjetnosti Republike Srpske, 2016) Šljivić, Milan; Fragassa, Cristiano; Pavlović, Ana; Kraišnik, Milija; Ilić, Jovica; Stanojević, Mićo
This paper presents the advantages and the process of making of complex functional parts using additive manufacturing technology. Design and manufacturing of components were performed at the Laboratory for Technology of Plasticity and Processing Systems at the Faculty of Mechanical Engineering in Banja Luka. The parts were designed using SolidWorks and Catia software packages. Then, CatalystEX and Simplify3D software packages were used to process the CAD model and to prepare it for 3D printing, which included defining of the process parameters, generating layers and support. Functional parts were produced on 3D printers based on the principle of material extrusion. The results of this study show that additive manufacturing technology, specifically technology based on material extrusion, enables very fast production of complex functional parts, with high accuracy and much lower costs and development time compared to conventional technologies.
An Intuitionistic Fuzzy Multi-Criteria Approach for Prioritizing Failures That Cause Overproduction: A Case Study in Process Manufacturing
(MDPI, 2024) Sudžum, Ranka; Nestić, Snežana; Komatina, Nikola; Kraišnik, Milija
Overproduction is one of the most significant wastes of Lean that can occur in any manufacturing company. Identifying and prioritizing failures that lead to overproduction are crucial tasks for operational managers and engineers. Therefore, this paper presents a new approach for determining the priority of failures that cause overproduction, based on an intuitionistic fuzzy Multi-Criteria Optimization model and the Failure Mode and Effects Analysis framework. The existing vagueness in the relative importance of risk factors and their values is described using natural language words, which are modeled with trapezoidal intuitionistic fuzzy numbers. Determining the relative importance of risk factors is defined as a fuzzy group decision-making problem, and the weight vector is obtained by applying the proposed Analytical Hierarchy Process with trapezoidal intuitionistic fuzzy numbers. The compromise solution, as well as the stability check of the obtained compromise solution, is achieved using the proposed Multi-Criteria Optimization and Compromise Solution with trapezoidal intuitionistic fuzzy numbers. The proposed model was applied to data collected from a process manufacturing company.
ANALIZA POUZDANOSTI PODSISTEMA ZA KOPANJE ROTORNOG BAGERA ER - 1250 RELIABILITY ANALYSIS OF BUCKET WHEEL DRIVE ON BUCKET-WHEEL EXCAVAVTOR ER - 1250
(Elektrotehnički fakultet, Univerzitet u Istočnom Sarajevu, 2010) Trifković, Spasoje; Kraišnik, Milija; Radić, Nebojša
Rad prikazuje izračunavanje pouzdanosti podsistema za kopanje bagera ER – 1250, za vremenski period od 2006. do 2009. godine. Za analizu otkaza korišćene su dvije metode iz teorije pouzdanosti, analiza stabla otkaza (FTA) i EFTES metoda alokacije pouzdanosti iz razloga njihove velike primjenjivosti i upotrebljivosti u analizama svih perioda životnog vijeka. Za realizaciju proračuna razvijen je programski paket za izračunavanje alociranog inteziteta otkaza i pouzdanosti.
ANALYSIS OF MICROSTRUCTURAL DAMAGE ON C45E STEEL IN THE PROCESS OF COLD UPSETTING OF A CYLINDER
(Faculty of Technical Sciences, Institute for Production Engineering, 2016) Kraišnik, Milija; Vilotić, Dragiša; Šiđanin, Leposava; Šljivić, Milan; Stefanović, Milentije; Ilić, Jovan
From the production point of view, the appearance of cracks of metal components is very negative, except in some metal forming processes when fracture is deemed necessary in order to obtain a product with the required characteristics. However, in general a plastic crack stops further forming processes and is thus a major factor limiting the increase of productivity, especially in cold metal forming. Previous studies have confirmed that the mechanism of nucleation, growth and coalescence of microcavities, which control the level of microstructure damage and lead to initiation and expansion of fracture, are influenced by various factors, with the generated stress state in the forming zone having the strongest influence. In this paper, these problems were investigated in the process of upsetting of cylindrical sample with flat plates. Based on the SEM examination of the microstructure of C45E steel with the aim to quantify microstructural damage and the FEM analysis of the stress state in the critical zone of forming, it can be concluded that there is a different impact of individual components of stress on the accumulation of critical level of damage.
APPLICATION POTENTIAL OF SOME CRITERIA OF DUCTILE CRACK IN BULK FORMING PROCESSES
(University POLITEHNICA Timisoara, 2016) Kraišnik, Milija; Vilotić, Dragiša; Šiđanin, Leposava; Stefanović, Milentije; Anić, Jelica
Ductile crack criteria are unavoidable tool for material formability analysis. Their basic task is foreseeing the location of crack occurrence and critical value of deformation level in the course of forming process. However, in order to provide successful application of certain criterion it is necessary to be familiar with material characteristics, specificities of forming processes and forming conditions. For all the above mentioned reasons this paper deals with the analysis of application potential of some widely used criteria of ductile crack in cold bulk forming processes according to representative literature resources. Results can contribute better understanding of phenomenon of material microstructure damage and adequate choice of ductile crack criterion in the analysis of formability in various processes and forming conditions.
Characterization of Microstructural Damage and Failure Mechanisms in C45E Structural Steel under Compressive Load
(MDPI, 2022) Kraišnik, Milija; Čep, Robert; Kourˇil, Karel; Baloš, Sebastian; Antić, Aco; Milutinović, Mladomir
In this paper, the microstructural damage evolution of a steel with a ferrite–pearlite microstructure (C45E) was investigated during the process of cold upsetting. The development and the accumulation of microstructural damage were analyzed in different areas of samples that were deformed at different strain levels. The scanning electron microscopy (SEM) results showed that various mechanisms of nucleation of microcavities occurred during the upsetting process. In quantitative terms, microcavities were predominantly generated in pearlite colonies due to the fracture of cementite lamellae. In addition, the mechanism of decohesion had a significant influence on the development of a macroscopic crack, since a high level of microcracks, especially at higher degrees of deformation, was observed at the ferrite/pearlite or ferrite/ferrite interfaces. It was found that the distribution of microcavities along the equatorial plane of the sample was not uniform, as the density of microcavities increased with increasing strain level. The influence of stress state, i.e., stress triaxiality, on the nucleation and distribution of microcracks, was also analyzed.
Comparing the accuracy of 3D slicer software in printed enduse parts
(2019) Šljivić, Milan; Pavlović, Ana; Kraišnik, Milija; Ilić, Jovica
This study aims to compare the accuracy offered by 3D Slicer Software in printing end-use parts inside a Fused Deposition Modeling process of Additive Manufacturing. The purpose, in particular, is to investigate the surface quality and the dimensional stability of the manufactured parts comparing the effect of selecting a different 3D Slicer tool among Simplify3D, Cura and Slic3r 3D. With this scope, parts were produced using these process tools while results were analysed in terms of accuracy, production time and consumption of material. Results, graphically and visually presented, show significant differences in the dimensional and surface accuracy with an optimum outcome offered by the Simplify3D as best 3D slicer tool. The Simplify3D slicer has essential advantages in printed end-use parts because creates the 3D models with significantly better accuracy and quality support.
COMPARING THE ACCURACY OF MASTER MODEL AND THEIR REPLICAS PRODUCED BY RAPID TOOLING USING VACUUM CASTING
(Mašinski fakultet, Univerzitet u Banjoj Luci, 2019) Kraišnik, Milija; Ilić, Jovica; Jotić, Goran; Mačkić, Tihomir; Anić, Jelica; Gvero, Petar; Prochaska, Biljana
In this paper we compared the accuracy of an original master model which was used to make the silicone mold and mold cavity and its replicas obtained by the vacuum casting technology. This technology allows us to create small batches of parts based on the master model in a relatively short time. The aim of the paper is to compare the accuracy of replicas produced with the OEM part using a reversible engineering technique, that is, CAD to part.
COMPRESSIVE PROPERTIES OF COMMONLY USED POLYMERS IN ADDITIVE MANUFACTURING PROCESSES
(University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2017) Kraišnik, Milija; Šljivić, Milan; Ilić, Jovica; Anić, Jelica
Production methods based on additive manufacturing technologies represent a powerful approach to the rapid and efficient production of complex prototypes and functional parts from different materials. This paper presents the procedure of development and production of a holder using a fusing deposition modeling process. Since compression is the dominant load on the holder in exploitation, mechanical testing was carried out and the results obtained can contribute to adequate material selection.
DEVELOPMENT OF SMALL BATCHES OF FUNCTIONAL PARTS USING INTEGRATION OF 3D PRINTING AND VACUUM CASTING TECHNOLOGY
(University of Banja Luka, Faculty of Mechanical Engineering, 2017) Šljivić, Milan; Kraišnik, Milija; Ilić, Jovica; Anić, Jelica
In conditions of dynamic market environment there is an increasing requirement for rapid development and production of complex and functional parts from different materials. In this paper, we present the process of development and production of small batches of functional parts in the integrated system of additive and vacuum casting technology. All advantages of this integrated approach were used during the research. Data obtained from the manufacturer were used for the proper selection of materials and they relate to the value of mechanical characteristics.
EXPERIMENTAL VERIFICATION OF DIFFERENT THEORETICAL APPROACHES FOR DEFINING FLD
(Faculty of Engineering Hunedoara, University POLITEHNICA Timisoara, 2014) Kraišnik, Milija; Vilotić, Dragiša; Šiđanin, Leposava; Petrović, Žarko
Workability of materials is the possibility of permanent changes in shape and dimensions of workpieces without cracking or other forms of damage to the structure. This property, which numerically valorized by size of limit effective strain, depends on type of material, the initial structure and processing conditions. This paper shows results related to the defining of FLD in bulk metal forming processes, based on theapplication of various theoretical approaches for determining of mean values of ß – factor and strainlimit.
FABRICATION OF SMALL BATCHES OF FUNCTIONAL AND AUTHENTIC PARTS FOR OLD-TIMERS USING INTEGRATION OF MATERIAL EXTRUSION AND VACUUM CASTING TECHNOLOGIES
(Department of Mechanical Engineering, Aristotle University of Thessaloniki, Greece, 2017) Kraišnik, Milija; Šljivić, Milan; Ilić, Jovica; Anić, Jelica
This paper focuses on production of small series of functional parts for old timers, for which it is very difficult and in some cases impossible to find spare parts. Specifically, the paper presents the possibilities of designing and making authentic parts with special requirements of the owner or the collector of old timers. As a result of this study, a small series of authentic parts and replicas based on the existing functional parts of the oldtimers was designed and fabricated. The results of experimental studies have highlighted the advantages of production that is based on the integration of technology of material extrusion and vacuum casting, especially for small series of complex and specific products.
FEASIBILITY STUDY FOR REPLACMENT HEATING SYSTEM ON NATURAL GAS WITH PELLET BOILERS AT PRIMARY SCHOOL "SVETI SAVA " IN LUKAVICA
(Mašinski fakultet, Univerzitet Istočno Sarajevo, 2014) Vasković, Srđan; Gvero, Petar; Medaković, Vlado; Halilović, Velid; Milić, Davor; Marković, Biljana; Antunović, Ranko; Kraišnik, Milija
This study describes the possibility of installation of pellet boilers for the production of thermal energy for heating in the primary school "Sveti Sava" in Lukavica. Existing heating system with natural gas turned out to be very expensive with high costs in terms of consumption of natural gas on annual level but also due to the high price of natural gas. Alternative possibility of heating premises within the school is seen in the installation of boilers that use wood pellets as an energy source. Above all, wood pellet represents an environmentally clean fuel in terms of CO2 emissions, but also because of the availability of resource from nearby factories that produce pellets, it can be used as a domestic fuel. In this way, the story of sustainable community development is encouraged, as well as the flow of capital within the community is closed .
Industry 4.0 and New Paradigms in the Field of Metal Forming
(University North, 2021) Milutinović, Mladomir; Milošević, Mijodrag; Ilić, Jovica; Movrin, Dejan; Kraišnik, Milija; Ranđelović, Saša; Lukić, Dejan
Over the last few year, the metalworking sector has been undergoing rapid and radical transformations driven by global competition and the revision of the production focus that is being moved from mass customization to mass individualization. A results of this is introduction of new manufacturing strategies such as Industry 4.0, a concept that combines cyber-physical systems and promote communication and connectivity. Therefore, this concept changes not only the face of the manufacturing systems but also causes transformation of existing business models and the society as a whole. This paper deals with the recent trends and paradigms in the field of metal forming, resulting from the concept of Industry 4.0 and the modern market challenges. The maim attention is paid on the flexibility of manufacturing systems and recent developments in design of smart forming tools.
MATERIAL FORMABILITY AT BULK METAL FORMING, CRITERIA, METHOD OF DETERMINATION AND APPLICATION
(UNIVERRSITY POLITEHNICA TIMISOARA, FACULTY OF ENGINEERING HUNEDOARA, 2019) Vilotić, Dragiša; Kraišnik, Milija; Milutinović, Mladomir; Movrin, Dejan; Vilotić, Marko; Anić, Jelica; Ficko, Mirko
Material formability it is material ability to deform permanently in different stress condition without structure damage. The fracture limit of material in bulk metal forming is based on fracture and formability criteria. In metal forming, two formability criteria and two workability diagrams are being used: a) the strain based and b) stress based formability diagram. Strain based formability diagram represents the dependence of the principal strains on the free surface of specimen at the moment of the fracture occurrence. The stress based formability diagram represents the relation between limit strain and stress triaxiality ratio in the zone of fracture. In this paper, methodology of formability diagrams determination is presented and application of formability diagram for the limit strain prediction in multi-stage upsetting of prismatic specimen by V-shape dies is performed.
MORPHOLOGY OF STEEL C45E MICROSTRUCTURE DURING UPSETTING
(Faculty of Engineering Hunedoara, University POLITEHNICA Timisoara, 2015) Kraišnik, Milija; Vilotić, Dragiša; Šiđanin, Leposava; Petrović, Žarko; Šljivić, Milan; Stefanović, Milentije
Entirely understanding of all factors and mechanisms which influence nucleation and accumulation of ultimate level of material failure is necessary for adequate choice of material and rational projecting of metal forming technological procedure. The first step in research refers to the morphology characterization of material micro constituents during processing. This paper contains qualitative-quantitative analysis of morphology changes of ferrite and colonies of pearlite in the steel C45E microstructure during upsetting of cylindrical specimen with flat dies. Relative microforming level of ferrite grains was determined based on direct measurements, while indirect way has been suggested for determination of pearlite colonies forming ability. The approach is based on monitoring of area fraction changes of pearlite colonies in relation to area fraction of ferrite basis during upsetting process. The results of SEM testing have shown that ferrite grains and pearlite colonies are formed unequally.
NUMERICAL ANALYSIS OF FREE UPSETTING CYLINDER USING FEM WITH EXPERIMENTAL VERIFICATION
(Elektrotehnički fakultet, 2011) Radić, Nebojša; Kraišnik, Milija; Trifković, Spasoje
This paper describes numerical simulation of upsetting process of cylindrical specimen by flat die performed by Finite Element Analysis on the bases of results of experimental research. Software CATIA V5 R18 is used for modeling and simulation. Having in mind that during the upsetting process large deformation occurred, nonlinear analysis is performed. It is needed to take into consideration large displacement and contact friction, as well as large pressure cylinder and rigid die. Results gained by Finite Element Analysis and by experiment show high degree of similarity, so this way of modeling could be used for even more complex technology of plasticity.
OSNOVNI PRINCIPI I PRAVILA PRIMJENE LAKOG DIZAJNA U MAŠINSTVU
(Mašinski fakultet Istočno Sarajevo, Univerzitet u Istočnom Sarajevu, 2014-12) Đurić, Aleksija; Marković, Biljana; Pelkić, Srđan; Marković, Biljana; Antunović, Ranko; Kraišnik, Milija
Kroz ovaj rad biće predstavljeni osnovni principi i pravila primjene lakog dizajna pri konstruisanju mašinskih sistema. Takođe, rad će dati odgovore na pitanja koji je cilj i koje su strategije primjene lakog dizajna, koji se to materijali koriste za izradu i kako na pravi način izabrati adekvatne materijale, a da se kao rezultat dobije, ne samo smanjenje težine konstrukcije, nego i da se ona učini ekološki i ekonomski prihvatljivom. Cilj je da se naučnom, nastavnom i privrednom ambijentu približi ova savremena metoda u konstruisanju mašinskih sistema, koja će, u bliskoj budućnosti, predstavljati ključ za opstanak na svjetskom tržištu za sve kompanije iz oblasti mašinske industrije.
Polymers in Additive Manufacturing: the Case of a Water Pump Impeller
(Faculty of Mechanical Engineering, Belgrade University, 2017) Pavlović, Ana; Šljivić, Milan; Kraišnik, Milija; Ilić, Jovica; Anić, Jelica
This research aimed at evaluating which of the polymers commonly used for rapid prototyping in the process of additive manufacturing can also meet the functional requirements in the preparation of final parts. In particular, the investigation was focused on a water pump impeller as a practical case study. A comparison between mechanical properties was proposed for this scope. ABSplus, ABS and PLA polymers were considered. Materials were tested in tensile and bending conditions. Results showed that ABSplus and ABS polymers satisfy all the mechanical requirements, while PLA fails. Then, the impellers were built-in and tested. All functional requirements, together with the necessary stability were verified. In this way, it was proved that, by selecting a suitable polymer, additive manufacturing can be successfully used to produce complex final elements, thus leading to extremely fast production, high accuracy and precision and even lower costs compared to other conventional technologies.
SOME ASPECTS OF DEVELOPMENT OF DUCTILE CRACK IN THE PROCESS OF COLD BULK FORMING
(Faculty of Engineering Hunedoara, University POLITEHNICA Timisoara, 2017) Kraišnik, Milija; Šljivić, Milan; Anić, Jelica; Ilić, Jovica; Mijatović, Biljana
The main limiting factor in increasing the productivity of the process of cold bulk metal forming is the appearance of plastic fracture. However, proper design of a technological process can greatly increase formability of the material. For those activities it is necessary to fully understand all the factors that affect constituent stages of development and the appearance of macroscopic damage on metal components. Therefore, based on the available literature resources and our own research, the impact of the most dominant factors on accumulation of critical damage of microstructure in cold bulk metal forming processes with special reference to the impact of stress state was analyzed in this paper.

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