PDA

View Full Version : Thermofoiling for the rest of us



dirk
04-06-2005, 01:24 PM
I started this thread because I’ve got this crazy idea to try and build a Themofoiling machine. This idea came to me as I priced machines ranging from 50 to 150 thousand dollars. Why are these machines so expensive? Am I missing something?
The way I understand how it works is put adhesive on product, let cure for a specific period, then place PVC covering over product, roll it into a heating chamber (some use infrared bulbs), when it gets up to temp suck it down with a vacuum. Roll it back out and trim off excess.
I think I’ve got enough knowledge on the subject to get myself in some real trouble, so someone please set me strait. I know it can’t be that simple. I did find in my research that it takes the operators of these machines several weeks to get the hang of using them. The problems seem to be the right combination of adhesive, material, temperature and vacuum.

billp
04-06-2005, 01:51 PM
Dirk,
I think that it IS "doable", and as I get further and further into this "vacuum phase" I am currently experiencing I hope to try out some theories I have seen in print. When we made male plugs for a thermoforming project last year they apparently did not even use adhesive, they just heated thin sheets of plastic, dropped the frame down over a vacuum platen, and pulled enough vacuum to hold the now pliable plastic tight against the plug. I've seen reasonably priced electric heaters on the Lee Valley web page ($50), that should provide more than enough localized heat, and these vacuum pumps I have been playing with are stong enough to hold just about ANY pliable material in place. What we need next are suggestions, and sources for the "right" plastics to use...

PS, There WAS a Shopbotter at my NJ Camp last year that used his 'Bot to make MDF doors (......) and he then used his $80,000 thermofoil machine to finish them off. Apparently he was doing very well in this biz because this was his second thermofoil machine, the first couldn't keep up with his needs. he even got out of the kitchen remodeling biz, and ONLY made doors for other people. He has since sold his 'Bot, and I haven't heard from him in awhile...

gerald_d
04-06-2005, 02:09 PM
I have a sneaky suspicion that there is no vacuum involved - I think that for the thin doors they overlay a thin rubber membrane and then blow/press from the top.

Edited to add:

Bingo! After a Google on "membrane press" (http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GGLD%2CGGLD:2005-07%2CGGLD:en&q=membrane%2Bpress) found many references. Nice pics (http://www.ney.co.uk/machines/new-products/foilcoating/presses/topform.htm). A source (http://www.vacform.co.uk) of membranes.

A big international brand name for the PVC foil is "Renolit (http://www.americanrenolit.com/Products/Surfacing/Production/MembranePressing.asp)" - they even have a plant in my home village. (nice process step pics in that last link)

dirk
04-06-2005, 02:26 PM
I believe there are several ways this is done, the way Gerald mentioned is a press
like the following:
http://www.almex-online.com/vinyl_foil_presses.html

I think the following machine uses vacuum, however it does state 15 psi pressure, which very well could mean vacuum

http://www.almex-online.com/vacuum_formers.html

gerald_d
04-06-2005, 02:32 PM
Dirk, I added a link to Renolit in my post above. They also speak of vacuum in that link.

billp
04-06-2005, 03:05 PM
Here's the basic idea of it all; http://www.plasticsmag.com/features.asp?fIssue=Jul/Aug-00&aid=2884

richards
04-06-2005, 08:35 PM
If adhesive were not used, wouldn't the 'membrane' separate eventually from the MDF? Does the 'membrane' material incorporate some sort of heat sensitive adhesive? (I'm visualising the 'membrane' as something similar to thick shrink-wrap material.)

dirk
04-06-2005, 08:57 PM
I had overheard at IWF in Atlanta some early problems with thermofoil. One was yellowing of the material and another was seperation of the laminate. The new materials are resistant to yellowing. And I think some changes in type of adhesive or the method of using the adhesive was changed. I'm wondering if maybe some of the foils may already have some heat activated adhesives pre applied.

dirk
04-06-2005, 09:05 PM
Also look at this link to an article I ran across.
The growth of Northern Contours is amazing!
http://www.iswonline.com/wwp/200501/membrane%20pressing.cfm