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Polymers filled with natural-based fillers have shown growing demand/interest in recent years, including in additive manufacturing. Like most natural fillers in 3D printing, wood particles serve mainly as a filler that lowers the cost of the printing material due to their low price. However, could wood be used as a main ingredient to affect/improve the properties of 3D-printed parts? Several advantages, such as its reinforcing ability, biodegradability, availability as waste material from other industries, ability to be used in different forms or only in partial components, recycling options or even the use of its undesirable hydromorph-induced dimensional instability for 4D printing, indicate the importance of exploring its use in 3D printing. A review of publications on 3D printing with wood biomass and technologies involving the use of wood particles and components was conducted to identify the possibilities of using wood in additive technologies and their potential.

The effects of dielectric barrier discharge (DBD) plasma treatment on the dielectric properties of Norway spruce wood (Picea abies (L.) Karst.) were investigated using dielectric analysis. Dielectric constant (i.e. permittivity) and loss coefficient were determined at various frequencies. The resulting changes on lamellae specimens of different thicknesses were compared with the change in mass and moisture content. A significant influence of the plasma was found, leading to an increase of the dielectric constant by about 2%, and a decrease of sample mass directly after the plasma treatment by approx. 14%, whereas a reduction in moisture content by only about 0.6% and a corresponding change in loss coefficient were detected. Overall, the mechanisms of the observed changes remain unclear and seem mainly uncorrelated with the hitherto known chemical changes in wood surfaces caused by similar plasma discharges.

Proučevali smo vpliv temperature termične modifikacije na utrjevanje in kakovost lepilnih spojev. Uporabili smo les smreke, ki je bil termično modificiran pri temperaturah 150, 170, 190, 210 in 230 °C ter različna lepila: fenol-formaldehidno (FF) za vroče lepljenje ter tri lepila za hladno lepljenje: polivinilacetatno (PVAc), poliuretansko (PU) ter melamin-urea- formaldehidno (MUF). Utrjevanje lepil smo spremljali z merjenjem reoloških lastnosti z reometrom pri čemer smo namesto standardnih aluminijastih diskov uporabili diske iz termično modificiranega lesa z različno stopnjo modifikacije ter z različnimi vlaţnostmi. Uporabili smo oscilatorni test z "multiwave" tehniko merjenja. Ugotovili smo, da so PVAc, PU ter MUF lepila utrjevala počasneje glede na stopnjo termične modifikacije lesa, vendar so bili razlogi različni. PVAc in MUF lepili sta utrjevali počasneje zaradi slabše absorpcije vode v modificiran les, PU lepilo pa zaradi niţje vlaţnosti modificiranega lesa. Termična modifikacija lesa je vplivala tudi na striţno trdnost lepilnih spojev. Striţna trdnost FF lepilnih spojev je padala z naraščanjem temperature modifikacije lepljencev, kar je bila posledica manjše utrjenosti lepila in niţje trdnosti modificiranega lesa. Po namakanju v vodi se je striţna trdnost FF spojev prepolovila, vendar so bolj modificirani preskušanci obdrţali večji deleţ začetne trdnosti. Povprečna efektivna penetracija FF lepila je sicer nekoliko naraščala s stopnjo modifikacije, vendar razlike niso bile statistično značilne. Termična modifikacija je zmanjšala omočitev površine lesa z vodo, toda izboljšala omočitev površine lesa s FF lepilom. Pri spojih s PVAc lepilom sta striţna trdnost spojev in deleţ loma po lesu padala s stopnjo termične modifikacije tako pri suhih preskušancih kot po namakanju preskušancev v vodi. Trdnost suhih PU lepilnih spojev se je zniţala glede na stopnjo termične modifikacije lesa, vendar manj kot pri PVAc lepilu. Po namakanju preskušancev v vodi pa sta se trdnost PU spojev in deleţ loma po lesu povečevala s stopnjo modifikacije lesa. Razlog je bil verjetno v navzemu vode in nabrekanju lesa. Navzem vode med 24 urnim namakanjem lepljencev v vodi je padal s stopnjo termične modifikacije lesa. Pri MUF lepilu je striţna trdnost suhih spojev padala s stopnjo termične modifikacije nekoliko bolj kot pri PU lepilu, vendar precej manj kot pri PVAc lepilu. Po namakanju preskušancev je striţna trdnost MUF spojev padla na polovico začetne trdnosti suhih spojev ter bila neodvisna od stopnje termične modifikacije, vendar je deleţ loma po lesu ostal 100 %. Skupna ugotovitev pri vseh lepilih je bila, da višja kot je bila stopnja termične modifikacije, manjša je bila deformacija pri kateri je prišlo do loma ter bolj krhek je bil lom. Skupna delaminacija PVAc lepilnih spojev je bila precej velika in se je povečevala s stopnjo termične modifikacije lesa. Pri PU in MUF lepilnih spojih izrazite delaminacije ni bilo. In the thesis the effect of the temperature used for the thermal modification of wood on the curing of adhesive and on bond performance was investigated. Spruce wood, heat treated at temperatures of 150, 170, 190, 210 and 230 °C, and four different types of adhesives were used: one adhesive for hot pressing, phenol-formaldehyde (PF), and three adhesives for cold setting: polyvinyl acetate (PVAc), polyurethane (PU) and melamine-urea-formaldehyde (MUF). The curing of the adhesives was monitored by measuring their rheological properties with a rheometer. Wooden discs, prepared from wood that had been subjected to different degrees of thermal modification and having different moisture contents, were used, instead of standard aluminium discs. The oscillation test with the "multiwave" measurement technique was used. It was found that the PVAc, PU and MUF adhesives cured more slowly depending on the degree of thermal modification, but the reasons for the retardation of curing were different. PVAc and MUF curing was slower because of the lower degree of adsorption of water in the modified wood, whereas the PU cured slower because of the lower moisture content of the modified wood. Thermal modification had a significant influence on the shear strength of the adhesive bonds. The shear strength of the PF adhesive bonds decreased with an increasing temperature of thermal modification, because of the lower degree of adhesive cure and the lower strength of the modified wood. After soaking in water, the shear strength of the PF joints reduced by half, but the more strongly modified specimens retained a greater proportion of the initial shear strength. The average effective penetration of the PF adhesive slightly increased with the degree of thermal modification, but these differences were not statistically significant. Thermal modification reduced surface wetting with water, but improved wetting with the PF adhesive. The shear strength and wood failure of the PVAc adhesive bond (of dry specimens and after soaking in water) decreased with a higher degree of thermal modification. The shear strength of the PU adhesive bonds decreased with degree of thermal modification of the wood, but less than in the case of the PVAc adhesive bonds. After soaking in water the shear strength and wood failure of the PU adhesive bonds increased with the degree of thermal modification. The reason was probably water intake and swelling of the wood. The water intake after 24 h of soaking decreased with the degree of thermal modification of the wood. The shear strength of the MUF adhesive bonds decreased with the degree of thermal modification slightly more than that of the PU adhesive bonds, but much less than that of the PVAc adhesive bonds. After soaking in water the shear strength of the MUF adhesive bonds dropped to half the initial dry strength, and was observed to be independent of the degree of thermal modification. The average wood failure of the wood remained at 100 %. In the case of all the adhesives bonds is was noticeable that with a higher degree of thermal modification the deformation was smaller when failure of the bond occurred, and that the failure was more brittle. The total delamination of the PVAc adhesive bonds was quite high, and increased with the degree of thermal modification of the wood. Delamination of the PU and MUF adhesive bonds was not pronounced.

Merjenje reoloških lastnosti se večinoma uporablja za spremljanje kakovosti izdelkov in njihovih lastnosti v proizvodnji hrane, kozmetike, gume, plastičnih mas, barv, črnil in mnogih drugih izdelkov. Spremljanje utrjevanja lepil z merjenjem sprememb reoloških lastnosti z reometrom je razmeroma nova tehnika, ki omogoča merjenje dinamičnega strižnega modula, spremembe viskoznosti in izgubnega kota med utrjevanjem proučevanega lepila. V osnovi je podobna klasični dinamični mehanski analizi (DMA), saj vzorec materiala med utrjevanjem dinamično obremenjujemo in merimo njegov odziv na obremenitev. Rezultati reoloških meritev omogočajo natančno določitev točke želiranja in zamreženja lepila. Z dodatno opremo lahko hkrati spremljamo tudi spremembe dielektričnih lastnosti lepila med utrjevanjem ter na ta način ugotovimo povezavo med njegovimi dielektričnimi in reološkimi lastnostmi, kar je izjemno pomembno za aplikacijo v industriji lepljenega lesa. Measuring the rheological properties is often used for quality control in food, cosmetics, tires, polymers, colors, and many other products. Monitoring adhesive cure by measuring change of rheological properties is a new technique. This method enables measuring of dynamic shear modulus, viscosity change, and phase angle during curing of selected adhesive. It is similar to dynamic mechanical analysis (DMA), because the sample of material is dynamically loaded during curing and it response is measured. Rheological measurements allow to determine gel point and vitrification point. With additional equipment is also possible to measure change of dielectric properties and find out the correlation between dielectric and rheological properties, what is very important for application in laminated wood industry.

S termično modifikacijo lesu zmanjšamo ravnovesno vlažnost, izboljšamo dimenzijsko stabilnost, povečamo trajnost ter odpornost proti glivam in insektom. Termično modificiran les ima drugačne lastnosti kot naraven les, zato je lepljenje takega lesa običajno zahtevnejše. Študije so pokazale, da termično modificiran les lahko kakovostno lepimo z večino industrijskih lepil za les, vendar je pogosto potrebno prilagoditi pogoje lepljenja in/ali modificirati lastnosti lepila. Trdnost lepilnih spojev termično modificiranega lesa je v splošnem odvisna od vrste lesa in stopnje modifikacije ter vrste lepila. Težavno je predvsem lepljenje z lepili na vodni osnovi, saj je modificiran les bolj hidrofoben. Thermal modification of wood reduces its equilibrium moisture content, improves dimensional stability, and increases durability and decay resistance.Bonding of heat-treated wood is difficult, because of its modified properties. Several studies had shown that heat treated wood can be sufficiently bonded with most of industrial wood adhesives, but usually some modifications of bonding process and/or adhesive need to be made. Adhesive bond strength of heat-treated wood depends on wood species, degree of modification and type of adhesive. Especially bonding with waterborne adhesives presents difficulties, because heat-treated wood is more hydrophobic.

The withdrawal capacity of screws in heat-treated spruce wood (Picea abies Karst.) was measured in the radial and tangential directions. Wood was heat-treated at temperatures of 150, 170, 190, 210, and 230°C. Screw withdrawal capacity decreased as the degree of thermal modification was increased. Also,image analysis was used to measure the size of the deformed wood area around the screw, which increased with higher thermal modification temperatures. This leads to the practical recommendation that connections in heat-treated wood should be constructed with screws with larger diameters and deeper penetration. Moreover, larger spacing between screws is needed to ensure sufficient withdrawal capacity compared to non-treated wood

Energy efficiency is essential in the efforts to achieve a 20 % reduction of primary power consumption by 2020. It is widely recognized that the potential of energy saving in buildings is large. Considering the tendencies of energy production and price, it is becoming urgent to reduce energy consumption in buildings. The choice of materials for a building with a high energy efficiency becomes much more important and strategies for reducing the use of primary energy for the production of materials and components becomes key. Renewable building materials should already be integrated into the early phases of building planning. The positive trend towards wooden construction is dictated by international guidelines, where a wooden building is an important starting point, not only for low-energy, but also low-emission building with exceptional health and safety aspects. In Europe, the most comprehensive and widely used is a concept of ultra-low energy house, more precisely, the passive house concept. Most Slovenian buildings combine contemporary styling with a degree of energy efficiency that comes close to passive house standards. It is widely recognised that the Slovenian construction industry is relatively advanced in the field of low energy buildings. In the light of the growing importance of energy-efficient building methods, it could be said that timber passive house would play an increasingly important role in the future.

Namen magistrskega dela je bil proučiti različne programske opreme za obdelavo oblakov točk, pridobljenih s 3D laserskim skeniranjem. Delo je nastalo v okviru dela v podjetja LES CAD d.o.o., ki se ukvarja z načrtovanjem notranje opreme in pri svojem delu uporablja modelirni program TopSolid. Naredili smo pregled naprav za lasersko skeniranje in preizkusili skener Leica RTC360 s skeniranjem pisarne. Za obdelavo oblaka točk smo preizkusili naslednje programe: MeshLab, CloudCompare, Revit, Rhino in AutoCAD. Cilj je bil iz oblaka točk pridobiti datoteko primerno za uvoz v program TopSolid in izdelati natančen 3D model prostora, ki omogoča nadaljnje modeliranje notranje opreme. S pravilno izbiro programske opreme in ustreznega postopka smo uspešno pridobili datoteko za uvoz v program za modeliranje in pripravili model objekta. Ugotovili smo, da se z izbiro ustrezne programske opreme in obdelave zmanjša velikost datoteke ter olajša nadaljnje modeliranje opreme v izbranem prostoru. Čas obdelave se sicer ne zmanjša, se pa s skeniranjem občutno zmanjša čas meritev na objektu. Za podjetje LES CAD d.o.o., ki se ukvarja z načrtovanjem notranje opreme, je najprimernejša obdelava oblaka točk v programu AutoCAD ter izdelava končnega modela v programu TopSolid. S to kombinacijo lahko pridobijo model prostora, ki zagotavlja dovolj visoko natančnost za nadaljnje delo. The aim of this work was to investigate different software for processing point clouds obtained by 3D laser scanning. The work was carried out within the company LES CAD d.o.o., which deals with interior design and uses the TopSolid modelling program for its work. During the research we obtained an overview of laser scanning devices and tested the Leica RTC360 scanner by scanning an office. We tested the following point cloud processing programs: MeshLab, CloudCompare, Revit, Rhino and AutoCAD. The goal was to obtain from the point cloud a file suitable for importing into TopSolid and to create an accurate 3D model of the room, which would allow further modelling of the interior in the selected room. With the right choice of software and the appropriate approach, we managed to obtain a file for importing into the modelling program and create a model of the room. We found that choosing the right software and procedure reduces the file size and facilitates further modelling of the furnishings in the selected room. The processing time is not reduced, but the time needed to measure the objects is significantly shorter when scanning is used. For LES CAD d.o.o., which deals with interior design, processing the point cloud in AutoCAD and creating the final model in TopSolid is the most suitable approach. In this way, a model of the space is obtained that provides sufficient accuracy for further work.

Pohištvo za domače ljubljenčke, posebej mačke, predstavlja področje z veliko potenciala. Z znanjem o mačkah, prepoznavanjem njihovih potreb, z ustrezno izbiro materialov ter željami potencialnih kupcev lahko razvijemo ter skonstruiramo kvalitetno pohištvo, ki bo ustrezalo tako hišnim ljubljenčkom, kot tudi njihovim lastnikom. V diplomski nalogi smo se posvetili razvoju pohištva za mačke, zato smo naprej naredili pregled različnih karakteristik mačk, nato smo se osredotočili na že obstoječe primere pohištva oziroma opreme za mačke na trgu. S pomočjo anketnega vprašalnika smo preučili preference potencialnih kupcev. Ugotovili smo, da potencialni kupci strmijo po čim večji funkcionalnosti ter kvaliteti. Preferirajo svetle odtenke pohištva, izdelke v velikosti od 100 do 200 cm in s sorazmerno razporeditvijo odprtih, zaprtih prostorov ter prostora za praskanje. V programu SolidWorks smo na podlagi rezultatov anketnega vprašalnika zasnovali 8 modulov, katere odlikuje odlična modularnost. Pohištvo, skupaj z vsemi zasnovanimi moduli, smo poimenovali The Cat’s Decision. Tako v Sloveniji kot tudi v tujini še nismo zasledili podobnih modulov, zato menimo, da imajo le-ti velik prodajni potencial. Furniture for pets, especially cats, is a market with a lot of potential. By knowing about cats, identifying their needs, selecting the right materials and combining that with the wishes of potential customers, we can develop and construct quality furniture that will suit both pets and their owners. In the thesis we focused on the development of furniture for cats, so we first made an overview of the different characteristics of cats, then we focused on the existing examples of furniture or accessories for cats on the market. We used a questionnaire to study the preferences of potential buyers. We found that potential buyers are looking for maximum functionality and quality. They prefer light-coloured furniture in sizes between 100 and 200 cm, with a proportional distribution of open, closed and scratching areas. The results of the questionnaire helped us to design and construct furniture for cats. We designed eight modules in SolidWorks, which are distinguished by their excellent modularity. We named the furniture – including all the designed modules – The Cat’s Decision. We have not seen any similar modules in Slovenia or abroad, so we believe that they have significant sales potential.

V diplomski nalogi smo se ukvarjali s procesom uvoza in obdelave 3D modelov iz različnih formatov v programsko okolje SolidWorks in SWOOD. Narejen je bil pregled vodilnih programov, ki so prilagojeni za konstruiranje in proizvodnjo lesenega pohištva, s poudarkom na SolidWorksu. V predstavljenem podjetju od naročnikov pogosto dobijo 3D modele izdelkov v različnih formatih datotek, kar zahteva ustrezen postopek dela, da modele prilagodijo SWOOD modulu. Pri uporabi tega modula je zelo pomembno zaporedje korakov – prikazan je izbran optimalen proces urejanja uvoženih 3D modelov s programom SolidWorks. Podane so prednosti in slabosti uporabljenega programa ter morebitne težave. Izbrani program lahko s pravilnim postopkom dela precej skrajša čas za izdelavo vseh potrebnih dokumentov za proizvodnjo, vendar je pred tem treba precej časa vložiti v prilagoditev knjižnic potrebam in načinu dela v podjetju. This study examined the process of importing and editing 3D models from various formats in the SolidWorks software with added SWOOD module. The first part of this study was an overview of existing programs which are specified for the woodworking industry. In the company examined in this work the constructors often receive 3D models from clients in different file formats which have to be treated differently. With the use of a SolidWorks and SWOOD software environment the editing steps are very important, and the optimal procedure of editing imported 3D models with SolidWorks is shown. At the end the advantages, disadvantages and possible problems with this approach are given. With the correct work process, the selected software environment can significantly reduce the time required to create all the necessary documents for production, but it is necessary to invest a lot of time in adapting the library to the way the specific company works.

Oblikovali in natisnili smo vezne elemente, s katerimi bi skupaj z enostavnimi lesenimi elementi lahko sestavili estetsko zanimivo mizo, ki bi ustrezala zahtevam standardov. Miza je bila oblikovana tako, da je enostavna za sestavo in pri tem ni potrebna uporaba posebnih orodij. Konstruirana je bila s programom SolidWorks, v katerem smo s simulacijami obremenitev tudi preizkušali variante veznikov. Izbrano varianto veznikov smo nato 3D natisnili iz PLA-polimera, za ostale dele mize pa smo uporabili topolovo vezano ploščo in borove palice. Lesene in 3D natisnjene dele smo sestavili s poliuretanskim lepilom in vijaki. Mizo smo nato testirali po metodah standarda SIST EN 1730:2012 in zahtevah standarda SIST EN 12521:2010. Miza ni prestala prvega testa vertikalne obremenitve, saj so popustili trije vezni elementi. Na podlagi teh testov in simulacij smo nato konstruirali še tretjo verzijo mize. Simulacije v programu so pokazale, da bi ta miza lahko prestala večje obremenitve in pri tem imela manjše deformacije. Ugotovili smo, da je mogoče izdelati mizo s 3D natisnjenimi vezniki, vendar je za zadostitev zahtevam standarda SIST EN 1730:2012 potrebna še optimizacija celotnega procesa. We designed and 3D printed connectors that, along with simple wooden elements, allowed us to assemble an aesthetically interesting table that meets the requirements of the related standards. The table was designed to be easily assembled without the need for special tools. It was designed using the SolidWorks program, in which we also tested various connection variants with load simulations. The selected variant of the connectors was then 3D-printed from PLA polymer, and for the other parts of the table we used poplar plywood and pine elements. The wooden parts and 3D-printed parts were assembled using one-component polyurethane glue and screws. The table was then tested according to the methods of the SIST EN 1730: 2012 standard and the requirements of the SIST EN 12521: 2010 standard. The table failed the initial vertical load test because three connecting elements failed. Based on testing and simulations, we then designed another, third version of the table. The simulations in the program showed that this table could withstand higher loads and had lower deformations. We concluded that it was possible to produce a table with 3D connectors, but optimization of the whole process is still needed to meet the requirements of the standard SIST EN 1730: 2012.

V okviru diplomske naloge smo proučevali osnovne mehanske lastnosti in dimenzijsko stabilnost 3D natisnjenih vzorcev iz štirih različnih materialov v spreminjajočih se klimatskih pogojih. Uporabili smo čisti PLA ter tri lesno-plastične kompozite z različnimi deleži lesa (do 40 %, 15 % in 25 %). Vzorce smo najprej navlaževali, nato pa smo jih sušili ter spremljali njihove dimenzijske spremembe. S pridobljenimi informacijami o izbranih materialih smo se lotili priprave in izdelave vzorcev iz dveh različnih materialov (PLA in lesno-plastični kompozit) v različnih debelinah plasti v sestavljenem vzorcu. Za lažjo predstavo, kako se bodo naši preizkušanci odzivali, smo izpeljali računalniške simulacije v programu SolidWorks ter izbrali optimalne kombinacije debelin plasti in materialov, ki naj bi v spreminjajočih se klimatskih pogojih dosegli največje spremembe oblike. Material PLA je bil v vseh primerih izbran za pasivno plast, za aktivno plast smo izbrali materiala s 15 % in 25 % deležem lesenega prahu. Pri tako natisnjenih elementih smo ugotavljali njihov odziv na izpostavitev v vlažni klimi (RZV 88 %). S kombinacijo dveh materialov v enem elementu in z izpostavitvijo teh elementov v vlažni klimi smo sprožili avtonomen odziv sistemov (vzorci so se samodejno odklonili). Najbolj so spremenili obliko – se odklonili vzorci, ki so imeli v aktivni plasti material z večjim deležem lesa, na velikost in hitrost odklona pa vpliva tudi razmerje med debelino plasti PLA in lesno-plastičnega kompozita. In the thesis, we studied the basic mechanical properties and dimensional stability of 3D printed samples from four different materials in changing climatic conditions. We used pure PLA and three wood-plastic composites, with different wood ratios (up to 40 %, 15 %, and 25 %). The samples were first moistened, then dried and their dimensional changes monitored. With the obtained information on selected materials, we started preparing and making samples from two different materials (PLA and wood-plastic composite) in different layer thicknesses in the composite sample. To make it easier to see how our tests will respond, we performed computer simulations in SolidWorks and selected the optimal combinations of layer thicknesses and materials to achieve the greatest shape changes in changing climatic conditions. In all cases, the PLA material was selected as the passive layer, and the material with the 15 % and 25 % wood dust content was chosen as the active layer. In the case of such printed elements, we determined their response to exposure in a humid climate (RZV 88 %). By combining two materials in one element and exposing these elements in a humid climate, we triggered an autonomous response of the systems (samples were automatically curved. The samples, which had material with a higher proportion of wood in the active layer, changed the shape – curved the most, and the size and velocity of the deformation are also influenced by the ratio between the thickness of the PLA layer and the wood-plastic composite.

Tehnologije 3D tiska postajajo iz dneva v dan bolj dostopne vsakemu izmed nas. Močno se širi tudi sama izbira materialov namenjenih 3D tiskanju. Skozi zadnja leta vedno večji pomen pridobivajo okolju prijazni materiali, v katere sodijo tudi lesno-plastični kompoziti. V naši nalogi smo proučili, kako se 3D tiskani deli iz lesno-plastičnega kompozita, PLA in ABS odzivajo na površinsko obdelavo. Tekom eksperimenta smo določili nekaj osnovnih značilnosti premaznih sredstev in izmerili stične kote treh testnih tekočin na 3D tiskani površini, na podlagi katerih smo izračunali prosto površinsko energijo. Ugotovili smo, da z brušenjem izboljšujemo vodoodbojne lastnosti vseh materialov in znižamo hrapavost površine. Oprijem premazov je bil najboljši na podlagi iz lesno-plastičnega kompozita. Prišli smo do zaključka, da lahko vse uporabljene materiale površinsko obdelamo in s tem dosežemo željen končni videz površin (sijaj, barva) ter želeno gladkost. 3D printing technologies are becoming more accessible, and the choice of the materials used for 3D printing is also expanding greatly. In recent years, environmentally friendly materials, such as wood-plastic composites, are becoming increasingly important. In our thesis, we studied how 3D-printed parts made of wood-plastic composite, PLA and ABS materials respond to surface treatment. During the experiment, we determined some basic coating characteristics and measured the contact angles of three test fluids on a 3D printed surface, on the basis of which we then calculated the surface free energy. We found that sanding improved the water-repellent properties of all materials and reduced the surface roughness. The adhesion of coatings was best on a wood-plastic composite substrate. We conclude that all the used materials can be surface treated and thus achieve the desired final appearance of the surface (gloss, colour) as well as the desired roughness.

V diplomski nalogi smo preučevali različne verzije 3D tiskanega veznika za stol za domačo rabo. Namen raziskave je bilo nadomestiti originalni kovinski veznik, ki povezuje štiri noge in sedišče stola, s 3D tiskanim veznikom in s tem zmanjšati maso. Pri izdelavi veznika smo želeli uporabiti lesno-plastični kompozit ter s 3D tiskanjem izdelati oblikovno zanimivejši detajl stola. Veznik je bil po originalu modeliran v programu SolidWorks, v katerem so bile narejene tudi simulacije obremenitev. Simulacije so pokazale deformacije in napetosti na vezniku, hkrati pa območja, potrebna ojačitve. Uporabili smo tudi študijo topologije, katere namen je zmanjšati maso izdelka, vendar kljub temu ohraniti trdnost celotnega izdelka, in zmanjšanje deformacij, ki se pojavijo ob delovanju obremenitev. Ojačan model smo s pomočjo študije topologije optimizirali in preoblikovali. Optimizirana 3D tiskana veznika smo natisnili iz polilaktične kisline (PLA) in lesno-plastičnega kompozita ter testirali v Laboratoriju za preizkušanje pohištva po zahtevi standarda SIST EN 12520:2010. Optimiziran 3D tiskan veznik, narejen iz PLA materiala, je zahtevi standarda zadostil, veznik, narejen iz lesno-plastičnega kompozita, pa ni ustrezal, saj je prišlo do loma. Ugotovili smo, da je s simulacijami v programu SolidWorks mogoče dokaj natančno modelirati model, ki bo zadostili zahtevam standarda. S študijo topologije in natančnim poznavanjem lastnosti materialov je mogoče veznik optimizirati ter zmanjšati maso, ne da bi zmanjšali njegove mehanske lastnosti. In this thesis, we studied different versions of a 3D printed chair connector. The purpose of the research was to replace the original metal connector that connects the four legs and the seat of the chair with a 3D printed connector, thus reducing weight. For this purpose, we wanted to use a wood-plastic composite when making the connector and 3D printing to create a more interesting design detail of the chair. The connector was originally modelled in SolidWorks, in which load simulations were also made. Simulations showed deformations and stresses on the connector at the same time as the required reinforcement ranges. We also used a topology study, which aims to reduce the mass of the product, while still maintaining the strength of the whole product and reducing the deformations that occur under the action of loads. The reinforced model was optimised and redesigned using a topology study. Optimised 3D printed connectors were printed from polylactic acid (PLA) and wood-plastic composite and tested in the Furniture Testing Laboratory according to the requirements of the SIST EN 12520:2010 standard. The optimised 3D printed connector made of PLA material met the requirements of the standard, and the connector made of wood-plastic composite did not, as a fracture occurred. We discovered that simulations in SolidWorks make it possible to produce a model that will meet the requirements of the standard quite accurately. With topology study and accurate knowledge of properties of the material it is possible to optimise the connector and reduce weight without reducing the mechanical properties.

V diplomski nalogi je predstavljena uporaba tehnike zarezovanja dukte pri izdelavi izdelka. Cilj diplomske naloge je bil preskusiti različne vzorce zarezovanja, vpliv le-teh na upogibanje/krivljenje plošče ter zasnova izdelka z uporabo dukte tehnike in izdelava prototipa lesenega računalniškega ohišja. V prvem delu naloge smo preskušali različne vzorce zarezovanja vezane plošče in vpliv na upogibanje. Za izdelavo preizkušancev in izdelka smo uporabili furnirne vezane plošče različnih debelin, katere smo z laserjem različno zarezali ter jih testirali na tritočkovnem preizkusu, s posebno izdelanimi čeljustmi. Z izbranim vzorcem zarezovanja smo nato v programu SolidWorks zasnovali izdelek - računalniško ohišje. Izrez plašča z dukto vzorcem je bil izveden z laserskim razrezom. Pri izbiri tipa vzorca dukte so bili, poleg izgleda, pomembni tudi velikost radija, ki smo ga lahko dosegli pri krivljenju, velikost potrebne sile za ukrivitev dukte ter odpornost na dinamične obremenitve. The thesis presents the use of the “dukta” cutting technique in the manufacture of a product. The goal of the thesis was to test various cutting patterns, their impact on panel bending and product design using dukta patterns and the production of a prototype wooden computer case. In the first part of the research, we tested various patterns of cutting of plywood and their influence on bending. For the preparation of specimens and the product, we used plywood of different thicknesses, which were cut differently with a laser and tested using a three-point bending test with specially designed fixtures. We then designed in the SolidWorks computer program a wooden computer case using the selected cutting pattern. Laser cutting was used for cutting the computer case. Besides the appearance, the size of the radius which we could achieve in curvature, the size of the necessary force needed to bend the dukta pattern and the resistance to dynamic loads were all important when selecting the type of dukta cutting pattern used.

V raziskavi smo preskušali materiale za tiskanje iz PLA polimera z dodatkom lesnega prahu. Uporabili smo pripravljene filamente z vsebnostjo 10 %, 20 %, 30 %, 40 % in 50 % lesnega prahu glede na maso filamenta. S 3D tiskalnikom Zortrax M200 smo iz vsakega materiala natisnili 12 preizkušancev, ki smo jih po sušenju in tehtanju kondicionirali v komorah z različno vlažnostjo (relativna zračna vlažnost 33 %, 65 % in 87 %), ob tem pa spremljali spremembe dimenzij in mase. Po končanem kondicioniranju smo izmerili tudi upogibno trdnost in trdoto natisnjenih delov. Ugotovili smo, da je masa in vlažnost preskušancev naraščala ob kondicioniranju v vlažni klimi, kar pomeni, da les v filamentu vpliva na lastnosti natisnjenega izdelka. S preizkušanjem smo ugotovili, da upogibna trdnost in trdota natisnjenih delov padata z deležem lesnega prahu v filamentu. Vzrokov je predvidoma več: majhni delci lesa delujejo predvsem kot polnilo, pri tiskanju pride do nastanka praznih prostorov v strukturi in slabše zlepljenosti slojev, saj so imeli filamenti z lesnim deležem neenakomeren premer, kar povzroči neenakomerno ekstrudiranje materiala skozi tiskalno šobo ter pri večji vsebnosti lesnega prahu prihaja do mašenja tiskalne šobe. In this study, we tested printing materials from PLA thermoplastic with the addition of wood dust. We used filaments with a content of 10 %, 20 %, 30 %, 40 % and 50 % of wood dust based on the weight of filament. With 3D printer Zortrax M200 we printed 12 samples from each material, which were conditioned after drying and weighing in chambers with varying humidity (relative humidity 33 %, 65 % and 87 %), and measured changes in dimensions and mass. The bending strength and hardness of the printed parts were measured after conditioning. We found that the mass/moisture content of specimens increased during conditioning in a humid climate, which means that the content of wood in the filament affects the properties of the printed product. By testing, we found that the bending strength and hardness of printed parts are decreasing with the proportion of wood dust in the filament. There are several reasons for this: small wood particles act primarily as a filler, during printing several empty spaces and poor adhesion between layers occurs due to irregular diameter of manufactured filaments with wood particles, which causes uneven extrusion of the material through the print nozzle and with higher content of wood dust we get more nozzle clogging.