fiber-reinforced thermoplastics for vacuum forming?

[drcrash]

Does anyone here know anything about fiber-reinforced thermoplastics? Are any vacuum-formable, or do they all need multiple atmospheres of pressure to form? Are any reasonably priced?

[ViperTX]

Not much except they can be thermoformed....I would check with your regional plastics supplier....I always check with my local supplier Regal plastics....they are quite knowledgeable about what is available and happening in the plastics industry....I think they also know the trade mags for that industry.

[chan luci]

Hi,
Fiber reinforced plastics cannot be vacuum formed. But if the glass strands mat is laid on the mold, to take the desired shape, a vacuum chamber can be created using a thin cover to close gap between the glass mat and that of the outer surface. And using a vacuum pump, resin is transferred to reach all the corners of the design, enabling to build up thickness, make the resin wet and cover the pre-laid mat.

[igor]

You can compression mols fiber reinforced thermoplastics. You will need a male and female mold. Actually works very well but one can not mold complex shapes or lots of detail. The strength is amazing....

[--colin--]

If the material it "thermo"plastic, it IS heat formable. Thermoplastics soften with heat and stiffen when cooled - hence the name. FRP (fiberglass reinforced plastics) or fiberglass is made with "thermoset" resins, such as epoxy or polyester. Thermoset resins cannot be heat formed after the resin has hardened as the hardening is a one-shot process.

Glass filled thermoplastics are usually injection molded, but since they are thermoplastics, they should be heat formable as well, but I don't recall seeing this type of material available in sheet form.

Specifically, what type of fiber reinforced thermoplastic are you referring to?

[drcrash]

Glass filled thermoplastics are usually injection molded, but since they are thermoplastics, they should be heat formable as well, but I don't recall seeing this type of material available in sheet form.

I wish I'd saved a link, but I think I read something about some production car body panels being formed from fiber-reinforced thermoplastic sheets.
(Pressure forming, if I recall correctly.) The article was actually about "in-mold decoration," and the stress was on the film laminated to the sheets, which closely resembles an expensive paint job with clear coat, but is much cheaper.

I'm not sure these things are vacuum formable, though. I looked up some specs on some fiber-filled resins (not sheets) and the fibers apparently change the heat deflection temperature in a big way. Up to the point where the plastic is really gooey, the stiffness is dependent more on the fibers than the resin.

This makes me wonder whether you can't vacuum form them, because they're too stiff. Maybe if you get them to just the right temperature, so that the plastic is very gooey and the fibers can slide easily across each other... but it could be tricky.

Specifically, what type of fiber reinforced thermoplastic are you referring to?

I wish I could remember which ones I read about, but in any case I'm interested in whatever kind is easiest to thermoform, if it's easy enough that you can vacuum form it. (I could imagine that a glass-filled high-impact styrene would work, because the plastic is so formable and forgiving---maybe you could get it up to a high enough temperature that it's almost runny, and the fibers don't dominate the stiffness, without burning it.)

[--colin--]

I've read about the auto industry gaining ground on plastic molded body panels that come out of the mold with finishes that rival today's base coat/clear coat urethane finishes. But I have not idea of what type plastics are used. I suspect without high pressures, the filled plastics my loose their properties. It may also be difficult to produce thin sheets with high filler loading that could be utilized in simple vac-form processes.

It comes back to the original question and why are you looking for a reinforced vac-formable material?

[drcrash]

It comes back to the original question and why are you looking for a reinforced vac-formable material?

Basically because I want to be able to make more things by vacuum forming, especially structural things as opposed to merely decorative ones. I can make cool shapes and textures, but I want to make functional parts of various things.

Most of these things could be made with a sizable injection molder, but I can't afford that. I'm wondering if I could vacuum form them out of something that would end up stronger than, say, 1/8" acrylic or ABS, and maybe fill them in with a putty of epoxy and long-fiber glass if they need to be really strong. (That seems easier and less messy than laying up fiberglass by hand. For most things, I don't want to work hard enough to make a good mold for fiberglassing, or deal with gel coating, etc.)