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postupka izrade kalupai ulivanja smole. To sedešava prvenstvenozbog toga što je nemogućnadzor nad dešavanjimau kalupu, iliukratko ZATO ŠTO SENE MOŽE VIDETI ŠTASE DEŠAVA U KALU-PU. Iz toga je slediozaključak, da nam je zarad potreban materijalza kalup kroz koji ćemomoći da vidimo šta seunutra dešava. Nakonmnogih proba počelismo da radimo sa PVCplastičnom folijom.Kupujemo je pod imenomVakumska plastika.Ime dolazi od procesaizrade ambalažekoja je u širokoj upotrebi(amabalaža zubnečetke). Folija se možetoplotno obrađivati.Foliju savijamo prekoforme i ona nakon hlađenja zadrži oblik. Na nju se smolane lepi. Odlivak uliven u kalup od PVC folije ima vrloglatku površinu i izgled dopune je vrlo blizu sjaju kojiima površina stakla. PVC foliju upotrebljavamo zaspoljašnji kalup, dok za unutrašnji upotrebljavamo silikonskugumu (slika 2).Takav proziran kalup omogućuje nam uvid u procesrada i odstranjivanje nepravilnosti. Tako izbegavamonaknadno popravljanje grešaka. Sledi opis rešavanjaproblema prvenstveno preko upoređivanja s kalupomizrađenim od silikonske gume.Rešenja sa prozirnim kalupom1. Pričvrščivanje kalupa na staklo (slika 3)problemi: izlivanje smole, stepenica i prelivanje prekostakla, slivanje lepka za lepljenje kalupa u kalup.Kroz prozirni kalup vidi se da li je kalup svugde ipravilno zalepljen. Kao što to kontrolišemo kroz stakloprilikom pričvršćivanja unutrašnjeg kalupa od silikonskegume, možemo da kontrolišemo pravilno pričvrščivanjespoljašnjeg prozirnog kalupa kroz njegov providnizid (slika 4). To je kod kalupa od silikonske gume ilivoska mnogo teže postići. Prozirni kalup nam omogućavada jasno vidimo da li kalup dobro naleže uz stakloili postoji mogućnost nastanka veće stepenice. U vremenudok silikonska guma, kojom se na staklo lepi prozirnikalup, ne završi reakciju, možemo kalup bliže priljubitiuz staklo. Ako silikonska guma iscuri u kalup(slika 5), a to se dobro vidi, moramo da odstranimospoljašnji kalup, da ga očistimo i ponovno da ga učvrsmouldsand casts,mainly because it wasnot possible to see andtherefore to controlwhat was happeninginside the mould. Itmight therefore be possibleto obtain a transparentmoulding material.After experimentingwith several transparentmaterials, I choseto use a PVC plasticfoil sold as vacuumplastic, which is used toform the packing materialfor which it is widelyused (packing materialfor tooth brush).The foil is heated andfolded around the shape;after cooling, thefoil retains its shape(i.e. that of the object).It does not adhere to resin.Its surface is verysmooth and the cast isnearly as shiny as the glass surface. As a rule, I use PVCfoil to make an outer mould and silicone rubber to makean inner mould (Fig. 2).The use of such a transparent mould enables an insightinto the work process so that any irregulariy can beremoved – any later correction of faults is thus avoided.7. i 8. Na slici 7 vidi se trougao od neprovidnog materijala (alu folija)prilepljen na spoljašnji providni kalup. Na slici 8 osvetljen je kalup i lepose vidi senka koju baca trougao na unutrašnji zid kalupa od silikonkaučuka.Fig. 7 shows a triangle made of non-transparent material (aluminumfoil) glued to the outer transparent mould. Fig. 8 shows an illuminatedmould; a shadow thrown by the triangle on the mould’s inner wallmade of silicone rubber is clearly visible.Solutions with a Transparent Mould1. Fixing moulds to glass (Fig. 3)Problems: resin flows out, a step is formed and resinflows over glass, glue flows into the mouldThrough a transparent mould I can see whether themould is correctly attached to the glass surface. As Ican see through glass and control whether the inner siliconerubber mould is correctly fixed, I can also control,through the transparent wall, whether the outertransparent mould is correctly fixed (Picture 4). Thiscannot be done if the mould is made of silicone rubberor wax. If the mould does not fit tightly against theglass, this may result in the forming of a step, and I cansee this clearly. As long as the silicone rubber, used to securea transparent mould to the glass has not fully cured,the mould can be pressed more closely against theglass. If silicone rubber flows into the mould (Fig. 5),this can be clearly seen, and in such a case it is only necessaryto remove the outer mould to be able to clean offthe silicone rubber and then to replace the outer mould.In such a way any surprise is avoided upon opening themould (made of silicone rubber) and finding a small holeor hollow9, 10. i 11. Prodiranje igle u kalup. Injektiranje epoksi smole i naginjanje predmeta, čime se izbegava prodor vazduha u uglove kalupa.Injecting of epoxy resin by means of a needle penetrating the mould, and tilting the object to prevent the air from getting trapped inthe corners.157