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Windscreen manufacture for project car 1

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wrightti

wrightti

Automotive
Jul 5, 2009
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Hi,

Im looking for some information regarding windscreen manufacture. This is for a 1-off road vehicle (which is basically just my own project for now)

Ive also posted this question in the aeronautics forum, so I hope its ok to duplicate here.

An idea of the geometry I'm hoping to achieve is attached. Its largely a single curve at this stage to simplify manufacture.

Being a one off and for a personal project, expensive high pressure moulding techniques are out of the question. Obviously some sort of moulding will be required, and this is within my capability, though I imagine the surface finish requirements on any tooling would be very high.

Finally, Id like some advice on how to manage visual distortion. Is there some geometry (high curvature sections?) which will cause problems?

cheers guys

Tim
 
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Well honestly I'm completely open to suggestions here. Polycarbonate and acrylic are options which I have come across, but Im not fixed on anything yet.

Does anyone know of resin which might be suitable to lay up (or spray) over a mould for this application. From my searching I have only found people moulding acrylic etc over moulds at elevated temperature. I was thinking a resin layup could be done at room temperature.

Tim
 
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Without fiber, the resin will run off the mold, so you need to do the layup and cure until the resin gels in zero gravity.

That's why people thermoform acrylic or polycarbonate sheet.


Mike Halloran
Pembroke Pines, FL, USA
 
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I'm aware how resin behaves. I was wondering if there was one you could spray on in several coats, like paint, to build up a thickness. This way you wouldn't see so much running.

The reason I ask is I have seen some flat panels of purely resin which had excellent transparancy. Obviously its more of a challenge to do this on a curved surface.

Tim
 
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Have you red flagged your other thread yet.

When I know the feedback is all happening in one place I can contribute in that place.

It is best if you red flag your own double post as that looks better than leaving it and making us do it to you.

It is best if you copy all replies to date to the thread you intend to keep.

It is OK and if you red flag a thread with reply's it is a really good idea to post a short note directing anyone interested to the live thread.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
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I watched a special on the Cubans making the old cars survive and they were re-molding the Russian windshields in a steel tool.

I would think the steel would break the glass with delta T or CTE
at any rate they figured it out some how.

If you could find a close fit a water knife can cut the size. The contour will need a graphite drape mold and a lot of heat.



I don't know anything but the people that do.
 
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Have you given any thought to the cost of ever having to replace this?

Much more conservative to take an existing windshield that is widely available and cheap, and about right, and tweak the design to fit the design to fit the windshield.

 
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Have you seen the scratch resistance and chemical resistance of polycarbonate.

It can be improved by coating, but that is quite expensive and still not quite up to withstanding wiper blades over a dry dusty windscreen.

Do you know how much weight could be saved and chip and crack resistance could be improved by a PC screen, yet OEM still does not use it.

In pristine condition, its impact resistance is far superior to even laminated glass, but once exposed to chlorinated or aromativ hydrocarbons, the impact resistance falls to almost nothing and there is nothing to indicate the deterioration.

This does not matter so much for side and rear glasses or headlights, but I think it is unacceptable for the windscreen on anything but a pure fine weather race car.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
 
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Pat,
I agree with you, but since it's a one off project i am tempted to think it will not see that much road and grime and a PC screen would be a cheap way to have something acceptable for a while at least.
 
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Take a look at the scratch-resistant acrylics from Evonik... I beat on a sample of that stuff with some steel wool for several minutes and didn't notice even a hint of hazing.

Dan - Owner
Footwell%20Animation%20Tiny.gif
 
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Dan

It will be a coating. While normal acrylic has exceptionally good scratch resistance for a plastic and vastly better than untreated PC it is not even in the same ballpark as glass. To resist steel wool it needs a coating.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
 
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