vac forming temperatures?


Sr Hunter
So how hot do you heat your plastics? I'm just learning the fine art of vac forming, and end up with a LOT of waste... I burned (literally!) through 10 pulls last time to get my cod and butt finished.

Imagine you were pulling 0.093 ABS. What temp, and for how long would you heat it?
Its not really the temp, as much as the sag. i usually sag .06 about 3 inches before i pull it so on a .09 i would guess about 3.5 to 4 inches of sag. You want it to ripple like a water bed when its hot enough. Then pull it quick.
I assume your vac table is a clamshell style. That has always been a problem with those. to get enough sag you almost have to touch the heating element. SO you can put your parts on risers. you'll get better definition high and the bad definition will be on the riser. hope this helps. Plastic aint cheap.

one tip. hotter is better. If you get webbing(lines that pinch together) you went to hot.


Well-Known Hunter
Hmmm... it depends on your set up completely.

If you have something similar to the thurston james model from the prop handbook then you should be preheating your oven for at least 20-30 minutes.

I preheat mine for a full the time in between i clamp all my plastic and get everything else ready... molds...vacuum system..etc..

After that i usually only need to heat my HIPS for 3 minutes and it's ready for ultra crisp detail....
ABS doesn't take much longer...only 4-5 minutes. However, the ABS is not as prominent of a sag, so a quick hand in glove check to test the ripple should do it.

Be careful to not overheat though...those are just rough times...hand checking it will tell you if you have enough droop and play. If it's too hot, you'll probably break the seal...or have a really thin pull in some areas.

Use risers as well...or else you're going to be doomed with webbing issues for complex or demanding molds.

Having an assistant always helps, but to tell you the truth, i do it alone most of the time and end up with great results.

80% of the battle for me is getting the oven up to temperature.

Make sure it is insulated well also, if you're losing heat you'll never get desirable results.


New Hunter
The plastic industry says "Forming temperatures are 10 - 15 degrees higher than the deformation temperature of a material". While this is great input, the art is still better than the science. Find deformation temperatures here. The problem in real life, is that the temperature on the surface of the materials are lower that the temperatures in your oven. Most forming ovens in production shops are not adjusted to specific temps, just the sag as listed above are used. Hope this helps.