Thickness of Ultem Plastic Funnel 1

[prephil]

Hi, I'm designing a type of funnel for attaching to a drum. The funnel needs to be made from ultem (PEI PolyEtherImide) so that when it is attached to an barrel, the level can be read when it is full (as Ultem is opaque). I just want to find out is there a minimum thickness I should make the wall?

http://img150.imageshack.us/my.php?image=a579funnel3ja.jpg

 

[CoryPad]

According to GE Plastic's Ultem PEI Processing Guide:

ULTEM resin has very good moldability due to its good flow characteristics. It is a good choice for consideration in complex and multi-cavity tools and depending on flow length, can be molded in wall sections as thin as 10 mils 0.25 mm).

So, you should base the wall thickness on the part's needs, like stiffness or strength or thermal conductivity. If it isn't critical, then something near 1 mm should be good.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[MikeHalloran]

Ultem is still going to be opaque, even if you make it thin.

For reading liquid level through the part, translucent materials like polypropylene or transparent materials like SAN are indicated ... assuming that whatever is in the barrel doesn't attack them, of course.







Mike Halloran
Pembroke Pines, FL, USA

 

[dvd]

I wouldn't make it any thicker than 1/2 of the o.d.

 

[prephil]

Sorry, I meant to say transparent. Ultem is transparent. I'm always getting opaque and transparent mixed up.

 

[MikeHalloran]

Ah. It's available both ways. You have to specify what you want.





Mike Halloran
Pembroke Pines, FL, USA

 

[dik]

dvd: Hehehehehe

Mike: opaque (no light transmission) or transluscent (some light transmission)? By both ways, you mean either transparent or transluscent?

Dik

 

[MikeHalloran]

The GE page I found

http://www.geplastics.com/gep/Plastics/en/ProductsAndServices/ProductLine/ultem.html

says it's available in opaque and transparent grades. Of course if you want it strong, you get opaque. There are probably other differences as well.

I'm a little fuzzy on why someone would make a drum decanting funnel out of an expensive heat resistant resin; maybe the drum is on fire.




Mike Halloran
Pembroke Pines, FL, USA

 

[prephil]

Thanks for the link Mike. The drum will be not be on fire as far as I know (after hearing that joke I'm well awake now - haha). It just so happens we have a spare part liying around so....but I see your point. It was my superior who suggested it but I'll have a word with him.

Just talking to my colleague now and he said it's one of the cheaper grades of translucent materials (Ultem 1000). It's being used with a monomer and has to be UV resistant. Know of any other materials which would do the job?

 

[CoryPad]

What is the material flowing through the funnel? Ultem is in no way one of the cheaper grades of translucent (or transparent) materials.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[ajamnia]

Ultem is a good material to use. In my experience, you should not use a wall thickness less than 40 or 50 mils - there are exceptions of course.

What you need to watch out is development of residual stresses during the molding process. Depending on the material flowing inside, associated loads or the environment, your part could develop micro cracks and fail.

Ali

 

[prephil]

It is a type of monomer used for making contact lenses which cannot be exposed to UV light or it will be rendered useless. What kind of cheaper translucent UV resistant material could I use?

 

[CoryPad]

Without complete information regarding the fluid, it is hard to identify appropriate candidate funnel materials. The transparent plastics cheaper than PEI include PC, PET, PMMA, and PS. They may not be suitable with your fluid. Are you expecting the funnel to block/absorb/reflect all UV so that the fluid is not irradiated? What is the UV source?

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[DanStro]

One thing I have run into while using Ultem (the opaque forms) is the availability. It seems to go through fits and starts. One time it may be plentiful while a few months later vendors are scrambling trying to get more.

But as far as the minimum thickness goes the stuff that I have used is relatively strong so the recommendation from CoryPad I think is reasonable, it can probably go a little thinner if you are real sure of the loading conditions.

HTH,
Dan

 

[prephil]

Expecting funnel to block UV. Light source is just from standard lighting inside a factory.