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The development of advanced materials and technologies based on magnetocaloric Gd and its compounds requires an understanding of the dependency of mechanical properties on their underlying microstructure. Therefore, the aim of the study was to characterize microstructural inhomogeneities in the gadolinium that can be used in magnetocaloric refrigeration systems. Microstructures of magnetocaloric gadolinium cylinders were investigated by light microscopy and FE-SEM (Field Emission Scanning Electron Microscopy), EDS (Energy-dispersive X-ray Spectroscopy), and BSE (Back-scattered Electrons) in both the extrusion and the extrusion-transversal directions. XRD (X-ray Diffraction) analyses were performed to reveal the presence of calcium- and fluorine-based compounds. Metallographic characterization showed an oxidized and inhomogeneous microstructure of the cross-sections. The edges and the outer parts of the cylinders were oxidized more intensively on the surfaces directly exposed to the processing tools. Moreover, a significant morphological anisotropy of the non-metallic inclusions was observed. CaF inclusions act as active nucleation sites for internal oxidation. The non-metallic, Ca- and F-containing inclusions can be classified as complex calciumoxyfluorides. The solubility of Er and Yb in the CaF was negligible compared to the Gd matrix and/or the oxide phase. Lower mechanical properties of the material are a consequence of the lower structural integrity due to selective oxidation of surfaces and interfaces.

The development of the product from stainless steel, which is produced for the client in large series, is presented. Technological optimisation was mainly focussed on the design of the deep drawing process in a single operation, which proved to be technologically unstable and therefore unfeasible for the prescribed shape of the product. Testing of prototype products showed unacceptable wrinkling due to the coneshaped geometry of the workpiece. For this purpose, the research work was oriented towards technological optimisation of forming operations and set-up of proper phase plan in order to eliminate the wrinkling of the material. Testing of several different materials of the same quality was performed to determine the appropriate input parameters used for digital analyses. The analyses were focussed towards the set-up of optimal forming process and appropriate geometry of the corresponding tool, which allowed deep drawing of the workpiece without tearing and/or wrinkling of the material. Performed analyses of the forming process in the digital environment were tested with experiments, which showed a good correlation between the results of both development concepts. Predstavljen je razvoj izdelka iz nerjavnega jekla, ki se za naročnika izdeluje v masovni proizvodnji. Tehnološka optimizacija je bila fokusirana predvsem na načrtovanje procesa globokega vleka v eni operaciji, ki se je izkazala za tehnološko nestabilno in zaradi tega neizvedljiva za zahtevano obliko izdelka. Testiranje prototipne serije je pokazalo nedopustno gubanje materiala zaradi konične oblike preoblikovanca. Zaradi tega so raziskave bile usmerjene v tehnološko optimizacijo preoblikovalnih operacij in vzpostavitev ustreznega metodnega plana za odpravo gubanja materiala. Testiranja številnih materialov enake kakovosti so služila izbiri ustreznih vhodnih parametrov digitalnih analiz. Te smo fokusirali predvsem v vzpostavitev optimalnega preoblikovalnega procesa in izbire ustrezne geometrije pripadajočega orodja. Ta omogoča globoki vlek preoblikovanca brez gubanja in/ali trganja materiala. Izvedene analize preoblikovalnega procesa v digitalnem okolju so bile preverjene z eksperimenti, ki so pokazali dobro ujemanje rezultatov obeh razvojnih konceptov.

In this paper, is given a systematic quantitative review of Single Point Incremental Forming (SPIF) process parameters that affect the formability of the polymer sheets during forming process. The obtained results from several relevant papers are collected and compared, such as a tool diameter, material thickness, step down, feed rate, spindle speed and their interactions were analysed. Only the most basic process parameters are selected because it has been shown that those ones are necessary for every SPIF process. This analysis contains data of an ideal operating range for each process parameter for seven different polymers. In the study, it has been shown that main parameters of SPIF process of polymers are not independent.

Paper deals with the description of the implementation of innovative Zn-PTFE coating into industrial production. Zn-PTFE composite coating is presumed to be used primarily on (high-strength) bolts. This coating offers excellent anticorrosive properties together with low friction coefficient. The article summarizes the technological production process of coating which was optimized to ensure homogeneous distribution of PTFE (polytetraflouethylene) particles in the coating and also to achieve optimal tribological parameters. The article mainly aims to present the structure of the industrial plating line and the general description of the technical conditions that need to be resolved in order to ensure this electroplating process to function properly.

This study deals with a modern way of detecting surface grease pollution. It explains, how to calculate the amount of oil pollution – how to find out the thickness of the oil layer and the related parameters.

This investigation proposes modeling of new deep drawing tool geometry for thin sheet metal. TS230 (W. nr. 1.0371, T50HF) D2, 8/5, 60 41 ST/Fin thin walled (0.155 mm) material properties are investigated and results are put in numerical simulation. Tooling with influential parameters is modelled and analyzed with ABAQUS software. Minimum drawing force necessary for selected tool geometry and overall tool behaviour is investigated. Heat generation of selected tooling of deep draw process and its influence on thin sheet metal deformation is also considered. Optimization of process is achieved by elimination of errors that appear in form of wrinkling, excessive thinning or fracture.

It is known that in warm and hot forming the forming speed and with it combined strain rate has immense role on material flow in bulk and sheet metal operations. In contrast, the influence of the strain rate on the flow curve is only rarely analyzed at room temperature. Presented work analyzes the influence of strain rate on flow curve of DC04 deep drawing material obtained by the uni-axial tensile test. After the evaluation of the flow curves as a function of strain rate the deep drawing of box-shaped test specimen was performed with two drawing speeds. The influence of the forming speed on the forming force and onset of necking was analyzed. Hitrost deformacije je pri preoblikovanju v toplem in vročem stanju ključni parameter procesa tako pri preoblikovanju pločevine kot tudi pri masivnem preoblikovanju. Nasprotno od tega je vpliv hitrosti preoblikovanja le redko analiziran za preoblikovanje v hladnem. V članku je analiziran vpliv hitrosti deformacije na krivuljo plastičnosti jekla za globoki vlek kakovosti DC04, pridobljeno z enoosnim nateznim preizkusom. Po ovrednotenju krivulj plastičnosti v odvisnosti od hitrosti deformacije smo z dvema hitrostima izvedli tudi globoki vlek preizkusne pravokotne škatle. Opazovali smo potek preoblikovalne sile in lokalizacijo materiala v odvisnosti od preoblikovalne hitrosti.

In this paper experimentally obtained data related to material mechanical properties, material behavior at elevated temperatures and numerical modeling of material creep responses are presented. Tensile tests at different elevated temperatures are carried out, and for some of these temperatures one-dimensional short time creep tests for different constant stresses are made. Before presented experimental investigations the used materials were not treated. The curves representing specimen strain elongation are also presented. The materials under consideration are 56NiCrMoV7 (1.2714) and X153CrMoV12 (1.2379)

Cold extrusion of steel is one technology which makes possible to produce accurate components of small and middle size, with very good mechanical properties and high quality of surfaces. However, due to relatively high costs of dies and equipment, this technology is economical only if batch size is big enough. In cold extrusion processes high pressures occur. In order to perform appropriate die design and die construction the amount and distribution of acting stresses should be known. Of special importance are contact stresses which take place between die and workpiece surface. Current paper investigates the contact stresses in radial direction at the container (die) wall in the process of cold forward extrusion of low carbon steel. Investigation has been carried out by two methods: Finite Element simulation and by experiment. Comparison of the results obtained by both methods shows good agreement.

Emerging photovoltaic (PV) solar cell technologies such as thin film and photo electro chemical (PEC) solar cells technology tend to be cheaper than PV cells made in standard technologies. In future it is expected that these technologies would increase their share in market. It is expected also that new converter types are going to appear in order to achieve low DC voltage/ high current conversion into the grid. In this paper H bridge active power filter with variable voltage is proposed. Its advantages and disadvantages are compared with standard active power filter (APF) and boost converter. This article also shows impact of different solar cells technologies on power converters and impact of advances in silicon and another material processing technology to other branches of engineering.

Goal of the paper is to determine the strain energy in different production processes giving the identical product by means of numerical and stochastic analysis. In order to predict the strain energy for the forming of bars and sheets (the same material Al Mg Si 1) and compare it for the processes of deep drawing and backward extrusion, the numerical and stochastic analysis and experimental investigations were done. Experimental research serves to check the correction and the verification of stochastic and numerical obtained results. Experimental investigations of both processes were performed according to an active experimental design ; it is the special form of the central composition plan applying the modeling and adaptive control in the processes with more variables. Also, according to the active experimental design the numerical simulation and stochastic examination were performed. The represented examples of strain energy determined at the deep drawing and backward extrusion processes shows how, with relatively few experimental data, it could be obtained model of strain energy. It is the base for the determining of optimal values of the process parameters.

The deformation limits of sheet metals, which are determined with localizationand fracture, represent an important parameter for the analyses ofsheet-metal forming processes. The forming limits of sheet metal are represented by a forming limit diagram (FLD), which shows the various deformation states. For an experimental determination of a FLD extensive and expensive tests are necessary. An alternative method for determining the forming limit curve (FLC) is an analysis performed using numerical simulations. This paper introduces a method for determining the forming limit curve for the whole range of the FLD for sheet metal. A simulation of the Marciniak test with the finite element method (FEM) was performed for hot-galvanized steel using the ABAQUS program. The criterion for determining the FLD with a numerical simulation is presented. Finally, the numerically obtained forming limit curve is compared with an experimental curve. Deformacijske meje pločevine, opredeljene z lokalizacijo in trganjem materiala, so pomemben parameter pri analizi preoblikovalnih postopkov. Meje dopustnih deformacij pločevine pri različnih deformacijskih stanjih najbolje prikazemo v diagramu mejnih deformacij. Za preizkusno določitev diagrama so potrebni obsezni in dragi preizkusi. Alternativna metoda za določitev krivuljemejnih deformacij (KMD) je analiza trganja materiala z numeričnimi simulacijami. V prispevku je predstavljena metoda določevanja krivulje mejnih deformacij za celotno področje. Z uporabo programskega paketa ABAQUS je bila izvedena simulacija MKE po Marciniaku preizkusa vroče cinkane jeklene pločevine. Opisan je kriterij za določitev KMD z numerično simulacijo in na koncu se primerjava numerično in preizkusno dobljene KMD.

Because of demands for increased vehicle rigidity, along with a simultaneous reduction of vehicle weight, the automotive industry is facing technological problems involving the manufacture of ever more complex formed parts. Often, the shape and mechanical properties of formed parts no longer permit their manufacture using conventional forming technologies, such as bending, stretching and deep drawing. Due to the complexity of primarily structural vehicle parts, tube hydroforming is increasingly used. However, because of the large number of process parameters, this procedure is very demanding. Forming pressures inside a tube with orders of magnitude of a few hundred to afew thousand bars represent a process limitation that requires special forming tools and machines. This paper presents the process parameters of tubehydroforming, the analysed process and the geometrical parameters, and theperformed numerical simulations for the forming of two typical formed parts-T-parts and Y-parts. Avtomobilska industrija se zaradi zahtev po povečevanju togosti vozil ob hkratnem zmanjševanju njihove mase srečuje s tehnološkimi problemi izdelave vse bolj zahtevnih preoblikovanih komponent. Oblikovne in mehanske lastnosti preoblikovancev pogosto ne omogočajo več izdelave z običajnimi preoblikovalnimi tehnologijami, kakor so krivljenje, izbočevanje in globoki vlek. Zaradi zahtevnosti predvsem strukturnih delov avtomobila se vse pogosteje uporablja preoblikovanje cevi z medijem pri visokih notranjih tlakih. Postopek je zaradi velikega stevila parametrov zelo zahteven. Preoblikovalni tlaki reda velikosti od nekaj sto do nekaj tisoč barov delujejov notranjosti cevi in pomenijo omejitev, ki zahteva posebna preoblikovalna orodja in stroje. V prispevku so predstavljeni parametri preoblikovanja cevi z medijem pri visokih notranjih tlakih, analizirani postopkovni in geometrijski parametri postopka ter izvedene numerične simulacije preoblikovanja dveh tipičnih preoblikovancev - kosa T in kosa Y.

Due to the increasing complexity of products, forming procedures are becoming ever more demanding. As a consequence, the holding procedure is becoming better adapted to the forming process through the use of various optimisation concepts. This paper presents the modern methods for the optimisation of holding, with an emphasis on the temporary optimisation of the blankholder force and the use of elastic and segmented blankholders. Preoblikovalni postopki postanejo zaradi zapletenosti izdelkov iz dneva v dan zahtevnejši. Pridrževanje pri globokem vleku se zaradi tega vedno bolj prilagaja poteku preoblikovalnega postopka, za kar se uporabljajo različni optimizacijski prijemi. V prispevku so predstavljeni sodobni načini optimizacije pridrževanja s poudarkom na časovni optimizaciji sile držala, elastičnih in segmentnih pridrževalih.

Pri postopku globokega vleka pride do tanjšanja stene izdelka. Ker na to vpliva več dejavnikov, smo na začetku diplomskega dela raziskali preoblikovanje pločevine in globoki vlek. Globoki vlek je temelj tega diplomskega dela, zato smo podrobno opisali postopek in parametre. Na podlagi tega smo določili tri glavne parametre, s katerimi smo izvedli eksperiment. Za načrtovanje eksperimentov smo uporabili Taguchijevo metodo. Eksperiment smo izvedli na hidravlični stiskalnici. Za merjenje debeline stene smo najprej raziskali načine in metode merjenja. Na podlagi tega smo izbrali metodo, s katero smo izmerili najmanjšo debelino stene lončka. Na koncu diplomskega dela smo analizirali rezultate, izračunali merilno negotovost in z uporabo programa dobili enačbo, ki predstavlja vpliv začetnih parametrov. S programom smo ugotovili, da imajo izbrani začetni parametri pomemben vpliv na debelino stene izdelka. In the deep drawing process, the wall of the product becomes thinner. Since this is influenced by several factors, at the beginning of the thesis we investigated sheet metal forming and deep drawing. Deep drawing is the foundation of this thesis, so we have described the process and parameters in detail. Based on this, we determined three main parameters with which we conducted the experiment. The Taguchi method was used to design the experiments. The experiment was carried out on a hydraulic press. To measure the thickness of the wall, we first investigated the ways and methods of measurement. Based on this, we chose the method with which we measured the minimum thickness of the wall of the pot. At the end of the thesis, we analyzed the results, calculated the measurement uncertainty and using the program obtained an equation representing the influence of the initial parameters. With the program, we found that the selected parameters have a significant impact on the wall thickness of the product.

Zaključna naloga obravnava analizo računalniških simulacij eno-točkovnega inkrementalnega preoblikovanja pločevine iz dvofaznega jekla. V začetnih poglavjih so prikazane teoretične osnove inkrementalnega preoblikovanja, računalniških simulacij in načrtovanja simulacij, potrebne za razumevanje naloge. Na podlagi postavljenega simulacijskega modela v programskem okolju Abaqus, so po postavljenem načrtu simulacij izvedene računalniške simulacije. Rezultati analiz simulacij po Taguchi in Random forest metodi ter njihova primerjava so prikazani s pomočjo programov MATLAB in Design Expert. Prikazana je vplivnost in korelacija nekaterih materialnih lastnosti na tanjšanje materiala in vertikalno komponento preoblikovalne sile. The final thesis deals with the analysis of computer simulations of single point incremental forming of sheet metal, made from dual phase steel. In the first chapters the theoretical basics of incremental forming, computer simulations and design of experiments necessary to understandig the tasks are shown. Based on the established simulation model in Abaqus software environmnet, computer simulations are carried out according to the design of experiment. The results of simulations, based on Taguchi and Random forest method, and their comparison are shown using MATLAB and Design Expert programs. The influence and correlation of some material properties on material thinning and vertical force component are shown.

Diplomska naloga izhaja iz problema, pri katerem je bilo potrebno za podan končni izdelek načrtovati geometrijo odkovka in tehnološki proces utopnega kovanja. Evalvacija tehnološkega procesa je bila izvedena s pomočjo programske opreme QForm UK Cloud 10.2.0, ki omogoča simuliranje različnih preoblikovalnih procesov. Problem je bil obravnavan kot 2D osnosimetričen. Obstoječa rešitev problema, je predstavljala izhodišče diplomske naloge, v kateri je izvedena podrobna analiza obstoječe rešitve in nadaljnja optimizacija geometrije odkovka ter procesa kovanja v skladu z navodili naloge. Rezultat diplomske naloge je izboljšana geometrija odkovka ob smiselnem upoštevanju vpliva temperaturnega raztezanja. Materialni izkoristek predstavljenega tehnološkega procesa znaša 81,4%. K izboljšanju procesa kovanja je bistveno pripomogel popravek začetnih dimenzij surovca, ustreznejša izbira maziva, dvig začetne temperature surovca in uporaba sestavljenih orodij. The diploma thesis is based on a problem in which it was necessary to plan the geometry of the forging and the technological process of hot bulk forging and trimming for a given final product. The evaluation of the technological process was carried out with the help of QForm UK Cloud 10.2.0 software, which enables simulations of various forming processes. The problem was treated as 2D axisymmetric. The existing solution to the problem presented the starting point of the diploma thesis, in which a detailed analysis of the existing solution and further optimization of the geometry of the forging and the forging process was carried out in accordance to the instructions of the thesis. The result of the diploma thesis is an improved geometry of the forging with reasonable consideration of the influence of thermal expansion. The material efficiency of the presented technological process is 81.4%. The correction of the initial dimensions of the blank, a more appropriate choice of lubricant, raising the initial temperature of the blank and the use of compound tools significantly contributed to the improvement of the forging process.

V magistrskem delu je predstavljen problem ožiganja injekcijsko brizganih polimernih izdelkov in odzračevanje orodja za injekcijsko brizganje termoplastov. Na začetku smo opisali osnove potrebne za razumevanje injekcijskega brizganja termoplastov, sestavo orodij za brizganje in načine odzračevalnih sistemov orodij. V nadaljevanju smo primerjali orodje s klasičnim odzračevanjem kalupne votline napram orodju s podtlačnim odzračevanjem ob pomoči zunanje vakuumske črpalke. Nato smo primerjali površino izdelkov narejenih z obema metodama, tako, da smo merili hrapavost in geometrijo izdelka. Ugotovili smo, da v primeru vakuumskega odzračevanja zmanjšamo ožiganje površine, s čimer je hrapavost izdelka manjša, izgled površine boljši, hkrati pa s podtlačnim odzračevanjem ne vplivamo na ostale dimenzije izdelka. In master's thesis we presented a problem of outgassing of injection molded poylmer parts as well as venting of molds for injection molding. At first, we explaind basic knowledge of injection molding, as well as parts of molding tools and types of venting systems. We compared conventional venting of mold with vacuum assisted mold venting provieded by external vacuum pump. In next step we compared parts surface by measuring roughness and geometry of samples. We found that by vacuum venting, we eliminate outgassing of surface, by which value of roughness is lower and look of measured surface is more desirable. At the same time other dimensions of samples remain unchanged.

Namen magistrskega dela je bila ugotovitev vpliva procesnih parametrov na iztiskavanje tankostenskega profila. Pri tem materiala nismo spreminjali, ampak je bil izbran predčasno. Za lažjo analizo smo uporabili metodo načrtovanja preizkusov, ki je narekovala, katere preizkuse na napravi za iztiskavanje smo izvedli glede na različne procesne parametre. Po zaključenih preizkusih smo iz profilov izdelali epruvete. Z njimi smo izvedli natezni preizkus in rezultate analizirali. Po končani analizi smo izvedli še potrditveni test. Ugotovili smo, da na natezno trdnost bistveno vplivata temperatura taline in vrtljaji polža naprave za iztiskavanje, medtem ko hitrost vleka nima bistvenega vpliva na natezno trdnost. The purpose of the master's thesis was to determine the influence of process parameters on the extrusion of a thin walled profile. In this case, we did not change the material, but it was chosen in advance. For ease of analysis, we used the Design of Experiment method, which dictated the tests we carried out on the extrusion machine, according to various process parameters. After the tests were completed, we made test tubes from the profiles. From them we performed a tensile test and analyzed the results. After the analysis, we performed a confirmation test. We found that the tensile strength is significantly affected by the temperature of the melt and the revolutions of the screw of the machine, while the pulling speed has no significant effect on the tensile strength.

V zaključni nalogi smo raziskovali vpliv mazanja na kakovost izdelanega statorskega segmenta. V teoretičnem delu smo se dotaknili osnov celotnega procesa rezanja in mazanja elektropločevine pri štancanju. V eksperimentalnem delu smo želeli ugotoviti, kako količina dodanega mazalnega sredstva na elektropločevino pri postopku štancanja vpliva na velikost poseda in raztržne sile statorskih segmentov. Posed smo merili na tlačnem preizkuševališču, raztržno silo pa na nateznem preizkuševališču. Naredili smo primerjavo, kako na velikost poseda statorskih segmentov vplivajo: količina dodanega mazalnega sredstva, dolžina sponk in spremenjena zavorna sila v orodju. Opazovali smo še, kako mazalno sredstvo vpliva na korozijo in na nabiranje laka na orodju. Ugotovili smo, da ima dodajanje mazalnega sredstva na velikost poseda majhen vpliv v primerjavi z različno dolgimi sponkami in korekcijo na zavorni sili. Ugotovili smo, da dodajanje mazalnega sredstva ščiti statorske segmente pred korozijo in, da mazalno sredstvo okrušen lak z elektropločevine sproti odnaša z orodja. In this thesis we have investigated influence of lubrication on the quality of the manufactured stator segment. In the theoretical part, we touched the basics of the entire process of cutting and lubrication of sheet metal during stamping. In the experimental part we have wanted to find out, how adding of different amounts of lubricant on the sheet metal during stamping process affects on the size of preasure stability and the size of pull off force. Preasure stability was measured with the compression test and pull off force was measured with the tensile test. We have compared how the amount of lubricant added, the depth of interlocking clips and the modified braking force in the tool affects the size of preasure stability of stator segment. Besides we have also observed how lubricant affects on corrosion and the accumulation of lacquer on the tool. We came to the conclusion that adding of a lubricant has a small effect on the size of preasure stability compared to different depth of interlocking clips and a correction to the braking force. We also came to conclusion that adding of a lubricant protects the stator segment from corrosion and that the lubricant carries away the chipped sheet lacquer from the tool.