Vacuum Forming Lexan

[offearth]

Good Morning All,

I have been tinkering with the idea of making stronger visors and parts for various helmets and armor parts using a vacuum former.
I've pretty much got the general table build and was thinking of using materials that are a bit more rigid than PETG sheets.
So, I'm asking all the wonderful members here, whoever shall see this; can you use lexan sheets instead of PETG?

If so, is there a max thickness that you would recommend and/or tips and tricks when working with lexan.

Thanks in advance!

 

[division 6]

The experience I've had with it (3 years at a sign shop) is that it's flexible and kind of rubbery when cut or ground.
We got ours in rolls at about 1/4" thick.

Never tried vacforming it, just petg and abs.

From what I was told, bullet proof windows exposed to uv light should be replaced every 3 years due to composition break down.

 

[offearth]

Knowing it’s flexible is good. That means it should work.

 

[zapwizard]

I haven't vacuum formed it, but I once did a project where I heated lexan in an oven and then hand-formed it over a buck. (No major details, just a curve). It worked well only if fully evenly heated. (Had to put some pans on each side to diffuse the heat).

Years later, I learned that is very good a absorbing infrared energy (It is used for the window on laser-cutters), and so it is hard to heat evenly if it directly exposed to the energy from heating elements.

 

[offearth]

I haven't vacuum formed it, but I once did a project where I heated lexan in an oven and then hand-formed it over a buck. (No major details, just a curve). It worked well only if fully evenly heated. (Had to put some pans on each side to diffuse the heat).

Years later, I learned that is very good a absorbing infrared energy (It is used for the window on laser-cutters), and so it is hard to heat evenly if it directly exposed to the energy from heating elements.

What temperatures does it become workable?

 

[zapwizard]

I don't know actually, we had a metal buck, so we just put it in the oven on top of it until we noticed it starting to sag. The first two times we ended up with bubbles in a few spots, and the third time (after adding pans) worked. We hand formed it to the buck using leather gloves.

 

[lmgill]

Lexan can be thermoformed very effectively. However, like acrylic, there are specific types of Lexan that are formulated for thermoforming, while others are not.
Polycarbonate (Trade name Lexan) is hygroscopic, meaning it absorbs water from the atmosphere. As a result, if the material is not "Factory Fresh" it needs to be "baked" to remove absorbed moisture. If this is not done, the absorbed water will turn to steam and cause bubbles to form in the material. The rule of thumb for this is 20 minutes for every .010" at 180 degrees f. (1/16th inch material 2 hours). Other sources cite much longer times, but this has worked for us.
Forming temps are in the 350- 450 f range

Here is a good guide to reference.

 

[offearth]

Lexan can be thermoformed very effectively. However, like acrylic, there are specific types of Lexan that are formulated for thermoforming, while others are not.
Polycarbonate (Trade name Lexan) is hygroscopic, meaning it absorbs water from the atmosphere. As a result, if the material is not "Factory Fresh" it needs to be "baked" to remove absorbed moisture. If this is not done, the absorbed water will turn to steam and cause bubbles to form in the material. The rule of thumb for this is 20 minutes for every .010" at 180 degrees f. (1/16th inch material 2 hours). Other sources cite much longer times, but this has worked for us.
Forming temps are in the 350- 450 f range

Here is a good guide to reference.

So, I’m assuming polycarbonate is able to perform this task?

 

[lmgill]

Well, since you give no specifics as to the size and shape of the parts you intend on making, nor do you state what type of Vacuumform machine you have. I can not say. The word "guide" in my post is a link to more information in case you missed it.

 

[offearth]

Well, since you give no specifics as to the size and shape of the parts you intend on making, nor do you state what type of Vacuumform machine you have. I can not say. The word "guide" in my post is a link to more information in case you missed it.

I have a diy one I made.
I’ll mainly be using it for visors.

 

[Pro Mod]

I'm not sure you’re going to gain any real advantage using polycarbonate over PET for the types of use you’re considering. Having used both, polycarbonate is the more temperamental to process, form and bond.

 

[offearth]

I'm not sure you’re going to gain any real advantage using polycarbonate over PET for the types of use you’re considering. Having used both, polycarbonate is the more temperamental to process, form and bond.

I wanted to make them more durable. PET visors I’ve had seem to be very flimsy. Break easily.

 

[Duncanator]

PETG is easier to vacuform, but polycarbonate can be vac-ed as well.

As Imgill said, you will want to bake any moisture out of it in order to avoid steam bubbles forming.
I vacuformed 1/4" polycarbonate shells for my combat robot, so it's totally do-able. I didn't bake it because I'd just picked it up from the plastic supplier - and I got bubbles. So unless you know that it has been stored in a dry environment, bake it.