Zaštita od korozije

[ljubitelj]

Purpena se ne stavlja na mesto koje je direktno u dodiru sa spoljnom sredinom, konkretno sa dnevnim svetlom (UV razara purpenu). Inace se purpena obavezno oblaze zastitnim slojem pri spoljnoj primeni.
Sumnjam da je sam pod galvanizovan, to prakticno niko ne radi ni onda ni danas jer nema potrebe na ravnim limovima koji cak i nisu noseci delovi konstrukcije.
Ali ako i jeste galvanizovan a nije popucala obloga lima bolje je nista ne dirati jer ionako nema uticaja na trajnost bilo kakva intervencija. Eventualno obnoviti zastitu koja je otpala- ispucala a koja treba da omoguci hidro zaptivnu membranu.

Obicno se cinkovanjem oblazu kutijasti profili ili druga mesta gde postoji mogucnost da se sakuplja vlaga (donja polovina vrata) ili predstavljaju nosecu strukturu bitnu za nosivost karoserije (vertikale i unutrasnji prag, spoljni prag, razni profili).

Vazno je konstruktivno obezbediti ventilaciju tako da se sto brze isuse takvi delovi karoserije jer bez vlage nema niti korozije.

Na tvom mestu ja ne bih nista dirao ako nema zaista fizickog ostecenja u smislu rupe i slicno i samo obnovio zastitu. Ako smeta nogama putnika pozadi izbio cekicem u kontra smeru na priblizno pocetno stanje ali onda je potrebna obnova zastite i sa spoljne i sa unutrasnje strane.

[dragvorl]

Sumnjam da je sam pod galvanizovan, to prakticno niko ne radi ni onda ni danas jer nema potrebe na ravnim limovima koji cak i nisu noseci delovi konstrukcije.

Steel and aluminum sheet rolls are the base material

The steel and aluminum sheet is delivered in coils that weigh up to 35 tons. The width, thickness and form of galvanizing depend on the part to be pressed. The thickness is between 0.65 mm and 3 mm. 82 percent of the new 7 Series model�s sheet metal components are made of high strength steel and approximately 95 percent of the sheet metals are already galvanized on both sides upon delivery. They are used for those parts of the body where protection against corrosion is of particular importance. The external sheet metal of the underbody, for example, is galvanized on both sides.

http://www.usautoparts.net/bmw/bmw/asse ... amping.htm

Body Galvanizing in Porsche 911

Thyssen steel = steel with Zinc layers on both sides; thickness of the Zinc layers varied from 10 um to 20 um, depending on exposure conditions (Frere, p. 201)

1970 – Galvanized steel (not Thyssen type) used in floor pan and wheel arches (Bob White in Pano V: 142); the “entire platform, including the floor, the longitudinal members, the wheel arches and the seat pans were galvanized.” (Boschen & Barth, p. 124)
1971 models – had galvanized steel in areas particularly exposed to rust (Frere, p. 201)
1972-1973 – Thyssen steel use began (Bob White in Pano V: 142)
1973 – Thyssen steel: rocker panels, inner rocker panels, floor pans, & some other parts (Chuck ******** in Pano V: 142)
1975 – Thyssen steel: entire body treated (Bob White & Chuck ******** {began in Feb. ’75 production for US cars; earlier for Euro cars – had trouble with paint} in Pano V: 142, 192)
1976 models – had Thyssen steel in entire body except roof (Frere, p. 201)
1977 models – on – had Thyssen steel in entire body (Frere, p. 201); an “important step forward was the use of zinc-coated sheet steel for the manufacture of the entire body structure (except for the coupe’s roof on early production cars). Coated on both sides, this made the structure virtually immune against the formation of rust….” (Boschen & Barth, p. 143)


The Zinc steel added 22 lbs. to the weight of the body structure (Frere, p. 202)

Pano = Panorama volume: page number
Frere = Frere, Paul. 1997. PORSCHE 911 STORY. 6th ed., Patrick Stephens Ltd. Newbury Park, CA.
Boschen & Barth = Boschen, Lothar and Jurgen Barth. 1978. THE PORSCHE BOOK: A DEFINITIVE ILLUSTRATED HISTORY. Argo Books

[ljubitelj]

Je li hoces da kazes da komplet sve dole vruce cinkovano na Porseima, ako sam dobro razumeo navode koje citiras.

Je li tako rade i sa kolima tipicne cene kostanja Korole ili slicnih mas produkcije ?

Pitam stoga sto ni MB ni Volvo koji odavno koriste cinkovanje to ne rade potpuno na svim limovima, tako kako je navedeno na primeru 911 iako spadaju u skuplje na trzistu pa mi je bas cudno da neki dosta jeftiniji auto ima 100% vruce cinkovanje komplet dole.

Ima li negde opis i za druge marke / modele kao sto navodis za Porse.

[dragvorl]

Nema ja sta da kazem, sve je tu napisano, to nisam ja izmislio. Sve apropo citiranog posta. Bez ljutnje. Evo i za Subaru.
link

[dragvorl]

Citao sam neku knjigu i naisao na neku nejasnu semu, pa sam kontaktirao autora, evo sta mi je odgovorio:

I am sorry the different types of zinc coated steel did not reproduce clearly in the book and that the diagram shows slightly old technology. However I can confirm that the outside part of the floorpan is galvanised as this is most vulnerable to corrosive action from the abrasive action of the stone chips plus deicing salt solution in winter. To update you on current practice I note that the 2012 Skoda Rapid body comprises 73.6% hot dip galvanised steel for most parts and 12.7% electrogalvanised for some parts such as roof where exceptional surface finish is required. The latest trend is to use press hardened steel for parts where critical crash resistance is required and since these are heat treated an aluminium-silicon coating is used (8.7% of parts). Only 5.0% of the panels are not coated and these are on inner parts not in contact with moisture etc.
The overall trend is now to use hot dip galvanised steel sheet because the quality is now much improved regarding surface and formability. Cost is also cheaper than the complex coatings such as Durasteel and electrogalvanised sheet. This applies to most European designs although the Japanese manufacturers prefer galvanneal (IZ) sheet for improved resistance welding - this is also made by hot dipping but with the added alloy conversion at end of process. The Rapid also has 1.3mm of PVC applied to the outer sill surface (outer floorpan) and carries a 12 year anti-rust warranty.

I hope this clarifies the situation and that you found the book helpful,

Kind regards,

[ljubitelj]

Nisam ni mislio da si izmislio, nego je moja dilema da li sam dobro razumeo pa otuda i pitanje. Nije bila losa namera.

Usput, setio sam se da je napravljen kompletan auto od nerdjajuceg celika (hrom nikl) De Lorean.

Citao sam negde analizu antikorozivne zastite svedskih autora pa je tu bio dat primer Volva koji iako cinkuje samo odredjene panele karoserije koji su noseci ima prosecni vek do pojave korozije oko 25 godina uprkos tome sto odavno daju garanciju samo 8 godina.
Tu je i objasnjeno kako Volvo ima sistem susenja supljina putem prisilne ventilacije tako da je na minimum smanjena mogucnost uticaja vlage.
Vruce cinkovanje je valjda tada bilo dovoljno skupo da se moglo stedeti na tome, ne vidim zasto inace svaki auto ne bi bio napravljen tako da bude otporana na koroziju.

Znam da je Audi 100/80 bio pocinkovan i da ima isto izvanrednu otpornost na koroziju pa su i danas ti primerci cesto bez problema i nakon blizu 30 godina.

Ok, jasno je da se danas obimnije koristi cinkovanje na autu.

[dragvorl]

[Bax]

Sta znam moja stara Pug 309, nije posustala pred korozijom nekih 20ak godina, nije nista ni krenulo...Imao sam i Colta, on se vec dobrano pojeo posle 10ak godina, rubovi sajtne i ostala galanterija..
Z10 nije nista pokazala evo vec 7ma godina.

[ljubitelj]

i Pug 405 je dobar limarijski. Ali recimo 505 sam video uzivo vise komada je bas los auto sto se korozije tice.
Iole solidan auto ne bi trebalo da ima pojavu tackice korozije prvih 15tak godina, naravno ako nije bio u karambolu ili na drugi nacin mehanicki ostecen pa krpljen.

Skoro sam imao prilike da zagledam Mercedes A na dizalici, korozija na sve strane i nema dela sasije i samog podvozja gde korozija nije zapocela delovanje.
To sam video i ranije isto na A klasi prve generacije.
Ne znam da li je to problem samo ea 2 komada ili je mozda i konstrukcija /izrada takva.

[snork]

Inače, ja sam mislio da se nanošenje cinka vrši elektrolitički, ali ako je reč o toplom postupku, to je svakako jeftinije.

EDIT: Vidim da se odgovor na poslednje pitanje nalazi u delu Dragvorlove poruke na engleskom. Znači - ekektrolitički samo za krov i druge delove gde je potrebna izuzetno ravna površina.