Thermoforming Plastics

Projects
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Does anyone have experience in Thermoforming Plastics?

I am really interested in learning more about this here are a few examples of the process

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I do it here and there. The only problem is unless you want to spend some money your stuck with a piece of plastic you can fit in your oven.

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so here is my thought on that lol

I want to get some small space heaters from like wally world and use those to heat the plastic

or take them apart and design a box to hold the heating elements

or just get some nichrome wire and build my own elements

what temp do you usually run your oven at when heating the plastic?

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Here is an option if you are not in a big hurry. Formbox. It is still in pre-order stage.

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@MichaelColey

oh yeah I saw that I am looking to build one that is either 24x48 or 48x48 inches

thanks though pretty cool for hobby stuff

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@PhilJohnson

oh yeah I was thinking of the electric heaters

I imagine the kerosene would be a bad idea

but what about propane? kinda like a bbq setup with burners on top

I guess that is the downside though burners have to be on top of the material and heat rises

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All the commercial ones are electric because it’s steady constant heat. Start small there is a lot to learn. You have to start putting drafts on all your vertical surfaces and drill thru holes in trapped pockets. The temperature and times depend on the plastic. I go by how low it’s sagging

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okay yeah I was curious about that and it I had to add like a 5 deg draft angle to the mold

when you drill the holes through the mold in different spots do you need to pull a vacuum through those holes or are you just giving a place for the air to escape?

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3-5 degree usually works. It’s just for demolding. Even zero can work if it has to be just use a air hose to force pieces apart. You need a vacuum pulling underneath the whole thing until the plastic cools. I made a vacuum table with a peg board as the top. Can be used as a downdraft table for sanding too.

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oh okay I see what you mean but for example see all these holes in the contour itself do they need to pull a vacuum as well?

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to me it seems like depending on the thickness of the plastic you would have dimples at each one of those holes

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Yea each hole has to pull a vacuum to hold it tight to the model. I don’t usually have a problem with dimples.

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oh okay thanks

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Using a heat gun won’t work for larger sheets, only small areas. The heat across a sheet needs to be constant and consistent because once it’s taken out of the heat source it starts to cool somewhat quickly. At least that’s the way it is with kydex. You want to transfer the hot piece to your press immediately so you get the best definition off your mold. I’ve done hundreds of sheets of kydex.

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When I was in college we had something very similar to this.

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would infrared lamps work?

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Lamps won’t work either. You want to be able to control the temps. You also don’t want to bring it up to full temp at once. I used a small convection oven. Start at 150° for 3-4 minutes, then 200° for 3-4 minutes…and so on until it reached 325°. Use a laser temp reader to read the actual temp of the kydex.

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I use electric barbecue charcoal starters. I have two of them installed on my vacuum machine. I use a surge strip to plug them both into. (and the elements are cheap…like 20 bucks each)

I do pieces of plastic around 16"x12" for my molds…so not huge. My material is .040" PETG plastic and Ive made hundreds of mold with it.

As far as dimples, I bet you will never see them. Especially if you use a thicker plastic than I. Most of my edges finish forming with a small fillet everywhere.

I use a 1hp vacuum pump for my table. Shop vacs have never impressed me and I’ve tried a handful of different designs.

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@EliottBrown

Hey eliott thanks for the info what type of vacuum pump do you use? do you have a picture or link?

thanks

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I work for a plastics company. We thermoform on a variety of commercial machines. Electric infrared heaters work well. They come in different shapes and sizes and need to be wired together or in zones.

Please know that thermoforming is dangerous. Have an emergency plan in place for heavy petroleum based smoke and fire. Failing to plan is planning to fail.

If you have specific questions please let me know. If I don’t have the answer I can get it.

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@SHubb

Oh I appreciate the info thank you

I am going to look up those heaters now it would be great if I could find a modular solution for my build

these seem like a good option

so in your experience on thermoforming is PVC the only plastic that is a big no no?

what class of fire extinguisher do you advise? maybe class B dry powder?

thanks