[frogger]

Hi all,

We’re a small manufacturer of our own products and I usually frequent the HAAS forum (we have a 2009 VF3ss). I’m looking to manufacture a clear lexan helmet visor and would like comments on our initial thoughts. We have no experience with vacuum forming but I have read several posts on this forum and there seems to be a wealth of knowledge.

Our idea is to initially make the home made style vacuum former to make sure the whole process will work. And this hopefully will give me the ideal stock size so we can build the machine the correct dimensions (as small as practical to avoid wasted material without sacrificing part quality).

Ok so here is the basic info,
2mm lexan material
Part size is approx 300mm x 175mm x 100 deep
I have access to a vacuum pump (see photo, we use it to hold down lexan for machining at the moment).
We’d like to build a machine similar to the Stelter unit but a custom size (we will only make one part)

Questions,
Starting with 2mm material, how much thinning would you expect over the more vertical sections? (roughly from experience).
Will this vacuum pump be sufficient?
Will a super polished tool give the best optical results? (I read that smooth surfaces could affect the vacuum draw over that section).
Is aluminum a good tool material or is a plastic tooling board better?
Please if you can see any obvious flaws in the plan just let me know.

Thanks
Frogger

[spektr]

Heres the deal....
If you are making helmet visors as a replacement for existing products in the field, you will have difficulty. Vacuum forming will not be the process of choice. Injection moldng is top of the list. If you are making lenses for something like ski goggles, you blank these from flat stock and drape form them in a semicircular mold lined with flannel. The problems with optics grade parts are not usually obvious at first glance, and require a bit of planning. as with most things these days, making it is a far cry from making it profitably.... I'd be able to discuss it with you if we arent competing on the same thing.. PM me idf you wish... Scott.

[frogger]

Thanks spektr,

Sounds like good advice. I could build both the female and Male mold parts and have the both lined in Flannel (is there any special type of flannel?). you have a PM,

[SPEEDRE]

As a mold maker at a company that made similar types of things, I no longer work there. Someone in China does it now. I made a compression mold for almost the same type of product. Here's the issues we had. One, standard Lexan, will, give a distorted view over the curve of the item. Second, it must be super polished, or Chromed. Much time, and stock, was wasted trying to vacuum form it, compression molding was found to produce the desired results. Third, you must use optical quality grade Lexan. I hope this helps a little. Good Luck Mate.

[frogger]

So far we've been able to have manufactured a few lenses to about 75% the quality we're looking for. Attached is some photos of the tooling being used. The next step will be Solid Aluminum tooling. Question?, What type of Felt/Flannel is best to use?

[frogger]

Photos

[spektr]

pm sent..

[frogger]

You have a PM