Thermo-molding PE & EVA

[Fonda]

I am thermo-molding crosslinked PE & EVA sheet into a floor mat and have hit the wall on some process details. I could use some HELP identifying temperature parameters for sheet preparation, as well as molding tips from some one who knows the process.

 

[patprimmer]

Have you tried the raw materials manufacturer.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[HDS]

I have used similar materials. The process parameters are very dependent on your equipment and material. Pat was right that the manufacturer is the place to start.

The advice I can give is to very closely monitor the "orientation" that the extruder puts into the sheet. ASTM d1204 is one of the tests for it.

Also it is a crystalline material with a distinct melting point. If you get near it the sheet will start to fall quickly. So be very careful not to overheat it.

What is your problem? Where are you located?

Is this an OEM or aftermarket part? Why this material?

 

[drcrash]

BTW, what's a good place to get relatively small quantities of EVA foam sheet cheaply?

I've been vacuum-forming Foamies from the craft store, but it only comes in limited thicknesses (2mm, 3mm, and 6mm) and sizes. (I can only find the 6mm in 9x12 sheets, which are way too small. I can find the 12 mm stuff as 2x2 floor mat tiles, but that's a bit too thick for my purposes.) Do they make 4mm? I'm guessing so, since EVA is used for so many things, but I haven't figured out where to find it.

EVA foam can be useful if you want a little loss of detail, e.g., to smooth out a shape as an intermediate step in making a buck. (I hate sanding.) Of course, the detail is much better on the inside, and I'm thinking of using it for making flexible molds cheaply.

I will second the idea that you want to be careful about scorching the stuff, and that it varies by make and model. Just among seemingly identical craft foams, Foamies brand cooks up (and scorches) faster than the off-brand stuff from Hobby Lobby, which I like better.

 

[dwightdixon]

Sounds like you would be better off on a forum intended for the hobby level processing. Lots of people overthere with your similar problems and experience.

link:

http://hobbymolding.com/modules.php?name=Forums

 

[drcrash]

Dwight,

Thanks for the link, but I've been there (and various sites about robotics, RC model building, prop and costume making, etc.), and there isn't much depth of engineering knowledge out there in the hobbyist world. (With a few exceptions, like Doug Walsh.)

But perhaps your point is really not that I'd be better off there, but that this forum would be better off... if you think so, you're likely right.

I do think I'm technically qualified to be here (Ph.D. in CS, a career designing and inventing things, etc.) but I'm a clearly far from my professional expertise when it comes to plastics.

Paul