Can you DIY thermoform Viton sheets?

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In summary, Viton rubber is pressure molded with heat or injection molded to form complex gaskets, but it behaves more like a thermoset resin. You cannot heat it up and form it again after it has been done one time.
  • #1
Stormer
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Viton rubber is pressure molded with heat or injection molded to form complex gaskets from what i have read. But do it behave like a thermoplastic where you can for example buy a sheet of finished Viton rubber, heat it up and then vacuum form it to the shape you want? Or is it more like thermoset resins where you can not heat it up and form it again after it has been done one time?
 
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  • #2
Here is the answer you don't want: "Maybe"

A Google search
(https://www.google.com/search?&q=softening+temperature+Viton)
returned many results for processing, usage, and cautions.

The first search hit was:
https://www.google.com/url?esrc=s&q...YQFXoECAUQAg&usg=AOvVaw1PSw6Q55Ua7EnV4qRM8WbR

Which states that the curing agent should be mixed with the fillers then added to the polymer. It also refers to the curing as "vulcanizing."

The document closes with:
"For more information, visit Viton.com"
 
  • #3
"Viton seals provide an indefinite seal for temperatures up to 400°F, and for temperatures up to 600°F they offer an excellent seal for more than 48 hours."
https://www.humphrey-products.com/news/viton-vs-buna-which-seal-for-your-applications
Which tells you that Viton does not flow when heated up to 600°F.

Stormer said:
But do it behave like a thermoplastic where you can for example buy a sheet of finished Viton rubber, heat it up and then vacuum form it to the shape you want?
You cannot change the shape of cured Viton by heating it.

In general, elastomer seals that are overheated develop more cross-links, so they become harder and more brittle. With Viton, that begins to happen slowly above 400°F, then rapidly above 600°F. Being less flexible results in a poor seal that may fracture, or will not remain compliant with the surfaces of the gaps it is sealing.
 
  • #4
Ok. So i guess it is more like a thermoset material. Is there anywhere for a DIY'er where you can buy Viton that is not cured so you can make your own custom shaped high temperature gaskets?
 
  • #5
https://www.martins-rubber.co.uk/blog/what-is-viton-our-essential-guide/
Write ... "Viton® is a brand name of DuPont for its synthetic rubber and fluoropolymer elastomer, commonly used in O-rings and other moulded or extruded products. This family of elastomers comprises copolymers of terpolymers of tetrafluoroethylene (TFE), hexafluoropropylene (HFP) and vinylidene fluoride (VDF or VF2), vinylidene fluoride (VDF) and hexafluoropropylene (HFP) as well as perfluoromethylvinylether (PMVE) containing specialty polymers".

To cast your own equivalent elastomers will be difficult because you will need to blend the components to get the required final chemical and mechanical properties.

You may be able to buy a two part kit from a resin supplier, or from a DuPont agent.

I would want to check first why you need to use a "Viton® like" polymer, and why a two part silicone compound would not be a much easier material to obtain, cast and cure. What are you trying to make, and why must it use Viton®.
 
  • #6
Baluncore said:
I would want to check first why you need to use a "Viton® like" polymer, and why a two part silicone compound would not be a much easier material to obtain, cast and cure. What are you trying to make, and why must it use Viton®.
I want to make some rolling diaphragm seals for a pressurized Stirling motor so i don't have to pressurize the crankcase. So the material needs to be both heat resistant and relatively strong (it will be backed up with pressurized oil). Maybe silicone will work if i get a hard enough type? But i don't think the really soft type of silicone i have usually seen will work for this.

It will be in the cold side of the cylinder, but still i don't think normal thermoplastic elastomers like the flexible 3D printer filaments are made of will take the heat the "cold side" can get up to without softening to much and failing.
 
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FAQ: Can you DIY thermoform Viton sheets?

1. What is thermoforming and how does it work?

Thermoforming is a manufacturing process in which a plastic sheet is heated and then formed into a specific shape using a mold. The heated sheet is then cooled and trimmed to create a final product. This process is commonly used to create packaging, automotive parts, and other plastic products.

2. Can Viton sheets be thermoformed at home?

Yes, Viton sheets can be thermoformed at home using a vacuum forming machine. However, it is important to have proper training and knowledge of the process to ensure safety and quality results. It is recommended to seek professional assistance for more complex projects.

3. What are the benefits of using Viton sheets for thermoforming?

Viton is a high-performance synthetic rubber that is known for its excellent chemical resistance, high temperature resistance, and durability. Thermoforming with Viton sheets allows for the creation of products that can withstand harsh environments and have a longer lifespan.

4. What tools and materials are needed for DIY thermoforming with Viton sheets?

The basic tools and materials needed for DIY thermoforming with Viton sheets include a vacuum forming machine, heat source (such as a heat gun or oven), mold, and Viton sheets. Additional materials such as clamps, release agents, and trimming tools may also be necessary depending on the project.

5. Are there any safety precautions to keep in mind when DIY thermoforming with Viton sheets?

Yes, it is important to follow safety precautions when working with heat and plastics. This includes wearing protective gear such as gloves and eye protection, working in a well-ventilated area, and following proper handling and disposal guidelines for the materials used. It is also important to have a thorough understanding of the thermoforming process to prevent accidents and injuries.

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