1. Initial study of immersion thermal manikin development and its manufacture from solid blocksIvo Pahole, Bogdan Valentan, Daniela Zavec Pavlinič, Mirko Ficko, Jože Balič, 2015, original scientific article Abstract: Article presents the development and manufacture of a new generation of thermal manikins that can be used for testing different personal protective equipment as used under extreme environmental conditions. The demonstrated steps from the initial idea towards the final product were taken with the help of modern CAD/CAM tools and CNC manufacturing procedures. This article also presents some of the problems that occurred and had to be solved during the designing, manufacturing and assembly of the thermal manikin.
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Keywords: extreme environment, personal protective equipment, safety, thermal manikin
Published in DKUM: 12.07.2017; Views: 1422; Downloads: 358
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2. Processing poly(ether etherketone) an a 3D printer for thermoplastic modellingBogdan Valentan, Žiga Kadivnik, Tomaž Brajlih, Andy Anderson, Igor Drstvenšek, 2013, original scientific article Abstract: PEEK, poly(ether etherketone), is one of the high-quality industrial polymers. It is widely used in extremely demanding areas like automotive, aircraft and space industries. Because of the fact that it is bio-compatible, PEEK is also used for medical implants that are usually made by milling a block of the material. The article presents the results of an investigation of processing PEEK on a 3D printer for thermoplastic modelling. The used procedure is one of the additive manufacturing procedures and, as such, it builds a product by adding material layer by layer to get the finished product. Commercially available machines are unable to achieve the required melting and environment temperatures, so a new machine was developed. The machine was designed and built at the company Ortotip d.o.o. and it is able to produce the parts of up to 130 mm Ž 130 mm Ž 150 mm. After the initial testing, test specimens, according to standards EN ISO 527-2: 2012 and EN ISO 178: 2011, were produced and tested at the facilities of the PEEK manufacturer Invibio (from the UK). The article presents the steps taken when developing the PEEK modelling machine, the test methods to verify the mechanical properties of manufactured products and the results of the material testing. The machine was developed to produce medical implants (specific maxillofacial prosthesis), but with additional testing (that will help to improve the mechanical properties of produced parts) practically all bone-replacement implants can be made.
Keywords: PEEK, 3D printer, implant, medical application, thermoplastic, FDM, biocompatible, additive technology
Published in DKUM: 17.03.2017; Views: 3203; Downloads: 181
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4. Development of a part-complexity evaluation model for application in additive fabrication technologiesBogdan Valentan, Tomaž Brajlih, Igor Drstvenšek, Jože Balič, 2011, original scientific article Abstract: Klasičnim odrezovalnim postopkom so se v zadnjih letih pridružili tako imenovani dodajalni postopki (slojevite tehnologije ali po domače 3D-tiskalniki). Če smo še pred leti vsaj okvirno vedeli kateri postopek izbrati za kateri izdelek, pa danes, ob upoštevanju vedno širše palete slojevitih tehnologij, temu ni več tako in le redki posamezniki še zmorejo slediti razvoju na tem izredno živahnem in hitro rastočem področju. Predstavljen je način določanja kompleksnosti izdelka na osnovi 3D-modela in uporaba izračuna pri izbiri izdelovalnega postopka ter določanju časa poobdelave pri določenih slojevitih tehnologijah. Članek opisuje osnovne značilnosti formata STL kot izhodne CAD-datoteke, ki predstavlja osnovo za analizo in razvoj postopkov določanja kompleksnosti oblike samega modela. Predstavljenih je več modelov iz realnega okolja, na katerih je izvedena analiza vhodnih podatkov in postopek določanja kompleksnosti oblike. Predstavljeni so aktualni izdelovalni postopki, primerni tako za izdelavo unikatnih izdelkov kot tudi za serijsko izdelavo, s posebnim poudarkom na slojevitih tehnologijah. Na osnovi temeljnih lastnosti izdelovalnih tehnologij so analizirani testni modeli in s pomočjo ocene kompleksnosti določeni primerni postopki izdelave oziroma čas, potreben za poobdelavo posameznega izdelka, izdelanega po postopkih slojevitih tehnologij. Rezultati so primerljivi z izkustveno določitvijo izdelovalnega postopka na osnovi ocene strokovnjakov, tako da je ob manjših dodelavah metoda tudi praktično uporabna. Sistem dokaj natančno izloči modele, ki jih je moč izdelati po postopku struženja, prav tako je ustrezno določena meja za uporabo rezkalnega stroja. Pri slojevitih tehnologijah enoznačno izbiro omejuje dejstvo, da te tehnologije v večini primerov omogočajo izdelavo izdelkov ne glede na njihovo kompleksnost. Izbira se je tako omejila na dve skupini, in sicer slojevite tehnologije, pri katerih je potreben dodaten podporni material, in slojevite tehnologije, pri katerih podporni material ni potreben, oziroma ga je mogoče reciklirati. Pri izbiri izdelovalnega postopka bi, ob upoštevanju določenih dodatnih omejitev posameznih slojevitih tehnologij, bila mogoča natančnejša izbira glede na kriterije, kot so čas izdelave, proizvodni stroški, material idr., vendar bi to zahtevalo aktualno bazo podatkov o samih postopkih. Sam način izračuna je bil izbran zaradi razmeroma preprostega izračuna in dokaj natančnega določanja kompleksnosti. Uporaba kompleksnosti za določanje izdelovalnega postopka pred tem ni bila raziskana. S problemom določanja časa poobdelave se danes srečujemo pri praktično vseh slojevitih tehnologijah, ta dejavnik pa bistveno vpliva tako na celoten čas izdelave kot tudi na ceno izdelka. Predstavljena rešitev omogoča izračun časa poobdelave na uporabniku razumljiv način in ob upoštevanju individualnih vplivov specifične naprave s preprosto primerjalno metodo glede na čas poobdelave testnih modelov.
Keywords: rapid prototyping, STl, complexity, shape, layered technology, technology selection
Published in DKUM: 10.07.2015; Views: 1652; Downloads: 101
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5. Possibilities of using three-dimensional optical scanning in complex geometrical inspectionTomaž Brajlih, Tadej Tasič, Igor Drstvenšek, Bogdan Valentan, Miodrag Hadžistević, Vojko Pogačar, Jože Balič, Bojan Ačko, 2011, original scientific article Abstract: Brezkontaktno optično zajemanje, merjenje in digitalizacija postajajo vedno bolj razširjeni postopki v sistemih zagotavljanja kakovosti. Prednosti optičnega skeniranja v primerjavi s konvencionalnimi kontaktnimi merilnimi postopki so preprosto zajemanje, visoka gostota pridobljenih podatkov ter povezava med povratnim inženirstvom in preverjanjem oblike. Optični skener se zaradi trirazsežnega zajemanja podatkov pogosto obravnava kot alternativa koordinatni merilni napravi. Prednost optičnega skeniranja je predvsem večja hitrost zajemanja podatkov, medtem ko natančnost še ne dosega ravni koordinatne merilne tehnike. Ta prispevek obravnava možnosti uporabe optičnega skenerja pri preverjanju natančnosti izdelave. Predstavljen je primer, pri katerem je za preverjanje natančnosti izdelka uporabljen optični skener GOM ATOS II. V prvem delu prispevka je predstavljeno specifično področje preverjanja natančnosti medicinskih vsadkov. Predstavljene so prednosti, zaradi katerih je optično skeniranje pri takšnih izdelkih primernejše od koordinatnega merjenja. V drugem delu prispevka so predstavljeni rezultati optičnega zajemanja geometrije merilnih kladic ter merilna negotovost postopka. V zadnjem delu je predstavljena neposredna primerjava rezultatov optičnega skeniranja in koordinatnega merjenja krogle. Glede na rezultate merjenja merilnih kladic in primerjave rezultatov merjenja krogle smo dokazali, da je natančnost optičnega skenerja GOM ATOS II primerna za preverjanje oblike medicinskih vsadkov z ozirom na zahtevano natančnost izdelka pred samim operacijskim posegom. Nadaljnje raziskave na tem področju bodo namenjene predvsem ločevanju in vrednotenju merilnih pogreškov optičnega zajemanja, ki so posledica nenatančnosti same naprave ter pogreškov, ki nastajajo zaradi naknadne poobdelave (poligonizacije) zajetih podatkov. Preizkus natančnosti optičnega sistema je bil omejen na merjenje merilnih kladic in na primerjavo meritve krogle s koordinatno merilno napravo. Prispevek predstavlja izvirno področje preverjanja natančnosti izdelave kompleksnih geometrijskih oblik. Predstavljena sta postopek zajemanja in poobdelave podatkov ter metoda preizkusa natančnosti naprave. Prispevek je namenjen vsem, ki se ukvarjajo s preverjanjem kompleksnih geometrijskih oblik, saj se bo z razvojem novih sistemov za optično zajemanje oblik povečevala tudi njihova natančnost. Te naprave bodo zato postajale vedno pomembnejše na širšem področju zagotavljanja kakovosti in ne samo na specifičnem primeru, predstavljenem v tem članku.
Keywords: 3D optical scanning, uncertainty of measurement, geometry inspection, rapid manufacturing, reverse enginering, quality assurance
Published in DKUM: 10.07.2015; Views: 1807; Downloads: 132
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6. A fast method to predict the cooling time of wax for investment casting procedureBogdan Valentan, Ana Pilipović, Tomaž Brajlih, Peter Sever, Ivo Pahole, Mirko Ficko, Jože Balič, Igor Drstvenšek, 2012, original scientific article Abstract: The investment casting of metal parts is a rapid tooling/manufacturing method for small series production, where wax pattern is produced separately and then extracted from the mould. The wax parts commonly used as patterns are usually obtained after wax casting silicone rubber moulds. The time needed for the wax to solidify is critical and difficult to predict. This article presents an experimental method for cooling-time determination using a simplified applicable solution (needed in hash industrial environment and short deadlines) based on real-life parts experience.
Keywords: odlivki, vosek, silikonski gumijasti modeli, čas hlajenja, hitra proizvodnja
Published in DKUM: 10.07.2015; Views: 1503; Downloads: 72
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7. Development of a 3D printer for thermoplastic modellingBogdan Valentan, Dušan Pogačar, Tomaž Brajlih, Tjaša Zupančič Hartner, Ana Pilipović, Igor Drstvenšek, 2012, original scientific article Abstract: Additive technologies are entering the market in all price segments and the development of new machines and materials is rapidly growing. Machines under 2000 EUR are more and more interesting for home and educational use. This paper presents the development of a 3D printer that shapes the parts layer by layer by depositing the material on a predefined position. The development is presented from the engineering point of view. The construction steps, the control and the actuator solutions are presented. The ABS plastic was analysed for its material properties. The 3D printer evolved from a prototype to the pre-production phase.
Keywords: polymers, rapid prototyping, additive technologies, 3D print
Published in DKUM: 10.07.2015; Views: 1525; Downloads: 140
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8. Basic solutions on shape complexity evaluation of STL dataBogdan Valentan, Tomaž Brajlih, Igor Drstvenšek, Jože Balič, 2008, original scientific article Abstract: Purpose of this paper is to present basic solutions on shape complexity, based on basic information of the STL data. Design/methodology/approach: Paper presents a few methods of mathematically evaluating the complexity of the shape. Methods vary from very simple based on the number of triangles in STL file, STL file size and the parts volume, to the more complex mathematical evaluation based on the basic relations of the STL data. Findings: We discovered that evaluation of shape complexity based only on basic data of STL data gives us some basic results on part complexity and can be used for further researches. Research limitations/implications: For parts with large block volume/part volume ratio and thinner parts with free form surfaces only the first method is suitable and gives suitable results. Practical implications: In a rapidly developing field of manufacturing technologies choosing the optimal manufacturing procedure is a difficult and crucial decision. Usually the decision is based on experience evaluation that is fast and can be optimal. Usually, this method produces goods results, but in some cases this method can lead to cost increases and reduced economic efficiency without us even knowing that. Therefore, it is crucial, that a fast and simple solution is developed, by which the optimal way of manufacturing can be determined. Originality/value: Choosing maximum efficient manufacturing processes on base of part complexity is a new perspective in manufacturing, which, properly evolved and complied can cause revolution in manufacturing optimization, especially in hybrid manufacturing processes.
Keywords: manufacturing systems, shape complexity, complex shapes, manufacturing optimization, engineering design, STL files, STL file parameters
Published in DKUM: 01.06.2012; Views: 2098; Downloads: 69
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9. Additive fabrication in metallurgy - case study of grey cast iron valve productionBogdan Valentan, Igor Drstvenšek, Tomaž Brajlih, Peter Sever, Simon Brezovnik, Jože Balič, 2010, professional article Abstract: Additive Fabrication technologies are well known from the last two decades. In that time Additive Fabrication technologies have evolved from strictly prototype part production into an option that can also be used to produce end-user parts. With development of Additive Fabrication machines capable of producing metal parts, a complete substitution of conventional metal casting technologies is possible. However, direct Additive Fabrication of metal parts is still not time/cost effective when producing large volume parts, and nowadays there is still lack of materials that can be used on those machines. This paper presents a method how a conventional sand casting process can be assisted by Additive Fabrication technologies. A sand mould pattern is produced by Selective Laser Sintering. Additive Fabrication is also used in direct manufacturing of cores.
Keywords: gray cast iron, layered technologies, rapid prototyping, rapid manufacturing, sand casting
Published in DKUM: 31.05.2012; Views: 2299; Downloads: 23
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10. RAZVOJ MODELA ZA OCENO ZAHTEVNOSTI OBLIKE IZDELKA IN UPORABO V SLOJEVITIH TEHNOLOGIJAHBogdan Valentan, 2010, dissertation Abstract: S skokovitim razvojem in razmahom naprav za proizvodnjo, tako klasičnih odrezovalnih kot postopkov slojevitih tehnologij (znanih tudi kot 3D tiskalniki), se pojavi vprašanje, kako med množico tehnologij in naprav izbrati ustrezno.
Delo opisuje osnovne značilnosti STL formata, kot izhodne CAD datoteke, ki predstavlja osnovo za analizo in razvoj postopkov določevanja kompleksnosti oblike samega modela.
Predstavljenih je več modelov iz realnega okolja, na katerih je izvedena analiza vhodnih podatkov in postopek določevanja kompleksnosti oblike.
Predstavljeni so aktualni izdelovalni postopki, primerni tako za izdelavo unikatnih izdelkov kot tudi za serijsko izdelavo, s posebnim poudarkom na slojevitih tehnologijah.
Na osnovi temeljnih lastnosti izdelovalnih tehnologij so analizirani testni modeli in s pomočjo ocene kompleksnosti določeni primerni postopki izdelave oziroma čas, potreben za poobdelavo posameznega izdelka, izdelanega po postopkih slojevitih tehnologij.
Rezultati so primerljivi z izkustveno določitvijo izdelovalnega postopka na osnovi ocene strokovnjakov, sistem določevanja izdelovalnega postopka je mogoče z manjšimi prilagoditvami praktično uporabiti.
Keywords: HITRA IZDELAVA, STL, ZAHTEVNOST, OBLIKA, SLOJEVITE TEHNOLOGIJE, IZBIRA TEHNOLOGIJE
Published in DKUM: 01.06.2010; Views: 3656; Downloads: 465
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