ORIGINAL POST – (Thanks to those who took the time to respond!)
We used to use a (paper-like) sheet of Teflon but more recently have
used baby powder or Armor All which hasn’t consistently prevented
sticking of the polypropylene. Is everyone out there using a sheet of
Teflon to prevent sticking? Any other techniques? Randy McFarland, CPO
RESPONSES
You can buy much stronger Teflon sheets from a good plastics supplier.
They come even strong enough to be used as conveyor belts etc. and are
available quite thick. There are also “boards” coated with Teflon
available from OTS and probably others, though rather pricy.
Teflon sheet. Get it from PEL in Cleveland. Using Teflon sheeting for
fifteen years no complaints . Change every three to six months depends
on workload. I speed rivet the corners to keep it in place on tray.
Works great. Good luck.
You might try to contact your local grocery store’s bakery. I purchased
oversized aluminum cookie trays that have the Teflon bonded to them. The
sheets are roughly 2’x3′ and very easy to maintain. If you leave the
plastic too long and it becomes liquid, just let it cool and it peels
off. As long as no metal scratches the Teflon surface they will last
quite a while. It sure beats replacing the sheets every couple of
months.
When our production department molds our HippO hip abduction brace
plastic, there are two things that we use that alleviate this problem.
1) The tray that we use is an aluminum tray with Teflon coating. We got
it from OTS. The aluminum tray with Teflon coating is much easier to
work with than putting Teflon sheeting over your tray.
2) We spray silicon on the tray about every five pulls. We use a silicon
spray can, only about $2.50 per can. It’s made by Gunk; there’s one made
by Stoner. We get it from Home Depot; PEL Supply also carries it.
I just started using Friddle’s 6 mil Teflon last week and it worked
great. I’m wondering if Teflon doesn’t “get old” after repeated use.
OTS had info on the Teflon coated trays in the PDQ oven I bought that
said “a slow degrading process occurs every time heat is applied to the
Teflon, temperatures over 500 degrees will accelerate this process”. So
this sounds like to me that Teflon is only “really good” for so long.
Randy we use Teflon sheeting on top of a Teflon pan in our PDQ oven. My
techs also clean the Teflon daily with food grade silicon that we get
from Grainger. It works like a charm!
Spray the sheet of Teflon with silicone.
We use a Teflon sheet in our infrared oven which is held down by a thin
metal
frame screwed down on each side of the sheet metal tray top. We replace
the Teflon sheeting about twice each year. Any residue left on the
sheeting, like
adhesives and such, seem to begin to degrade the Teflon as it is
reheated over and over again. That’s why we are wiping it down with
spray silicone
sometimes between each job. We have never had a sticking problem this
way.
Most people use the Teflon sheeting as a rule. The only other, really
viable, alternative is to have a sheet of aluminum coated with a
non-stick coating. Like Teflon or silicone epoxy. Just like you find on
your frying pan. At least, that’s what we’ve found that best works in
the ovens that we make.
You should be able to find someone locally who can coat it for you.
Remember that Teflon is a brand name and that there are numerous
different types of non-stick coatings that are being used for everything
from frying pans and other cooking equipment to snow skis and rifle
bores. What we use here is a silicone based epoxy that we apply with our
powder coating system. If you don’t have any luck finding a source in
your area, drop me a line and I’ll see if I can locate someone for you.
Or sell you one of ours. Whatever suits your purposes…….
Me personally, I like the sheeting. There are some drawbacks, but the
thing I like is that you can get the micro-perforated kind that allows
trapped air to escape and prevent air bubbles from forming under the
plastic.
I like to use Teflon sheeting to prevent the plastics from sticking to
the tray. You can purchase the Teflon sheeting from Friddles and SPS. I
like to rivet the sheeting to a thin sheet of aluminum, to prevent it
from rolling and wrinkles. It is necessary to clean these as a daily
routine, I prefer to use a silicone spray, make sure not to scrape the
sheeting while cleaning because it will cause problems in the long run.
If you are trying to avoid Teflon sheeting for some reason, you might
be able to use a Teflon grade silicone spray ( you can find industrial
grade parting sprays from MSC, McMaster-Carr, and Grainger)Make sure you
spray it in the morning before you turn on the oven, and follow up with
additional sprays through out the day. However you may find it more cost
effective by using the Teflon sheeting.
We currently use Teflon (thick sheet bolted to the tray) with silicone
spray applied after every plastic pull. Be careful with this as the
plastic can overheat fast.
Just bite the bullet, call OTS and order a Teflon tray. It pays for
itself and can be recoated.
We have been using the paper thin sheet of Teflon for years without
difficulty. I personally do not know of a better method. Occasionally
we will wipe the Teflon with thinner to remove impurities.
We also Teflon sheeting on a metal tray in our oven. I had trouble at
one time with poly and co-poly sticking to the Teflon. I realized that
if I was pulling an AFO after someone had pulled a BK check socket,
using PETG, my poly or co-poly would stick to the Teflon.
I now always spray the Teflon with a silicone spray and wipe with a rag.
That seems to clean any residue left by the PETG.
It as worked well, I no longer have the trouble with the plastic
sticking.
I spray one side of my plastic with silicone, let the propellant and
solvent evaporate so you don’t get a bubble when the plastic is heated
with that side placed down on the Teflon sheet in the oven. If anything
sticks it is just at the edges where the plastic expands. I use
automotive silicone lubricant but spray it in the lid and avoid any that
smell like oil or WD 40 because that type will smoke when heated. I put
a small anvil upside down on the Telfon to hold it down when I pick the
plastic off and put the side without the silicone on the cast to drape
mold so the plastic will adhere to itself before applying vacuum. I also
like to use baby powder (corn starch type over the nylon on a cast which
is still moist and talcum type on the nylon over a dry cast). Thanks
for the Armor All tip.
Teflon here. It works great as long as you clean it every once in a
while with spray silicon.
I have been using a thin self adhesive Teflon for the last 15 years
now and find it works very well. On earlier times we were spraying the
Teflon with silicone spray to help but now find that that is not
necessary.
With the adhesive backing, it is applied direct to the tray which we
slide out and peel the plastic off without much resistance.
I don’t know where you can find it in the states as I am in Australia
but hope this is of some help to you.
Regarding the advice to spray the pan with silicone, I have a
reservation that it contaminates the underside of the plastic and
creates an unreliable bond – assuming one is desired, such as with a
floor reaction AFO. One would have to be careful to place topside of the
plastic towards the model.
