IP64/65 Enclosure Design - Sheetmetal? Best Practices? 2

[TheSwener]

Hi folks, go easy - it's my 1st post

I'm in the process of designing several automotive-grade enclosures for power electronics (IP64-65 protection). My plan thus far is to do custom sheet metal, weld up as many edges as possible, and use gaskets on the lids and around all connectors.

Any thoughts? Recommendations for best practices, alternatives to sheet metal (considering prototype volumes only), etc? Any good resources out there?

Thanks in advance for your suggestions!

 

[drawoh]

TheSwener,

How big are your enclosures?

If they are small, machining from billet is a possibility. If production goes up, you can modify them into castings.

Plan on spending a lot of time figuring out your gaskets.

JHG

 

[itsmoked]

Buy a few small IP65 boxes from BUD, etc and look at the details.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[TheSwener]

Hi guys,

I'm doing various sizes, most are in the neighborhood of 5"x8"x20", one of them more like 8"x20"x40". I mentally ruled out billet already due to the size... pretty much anything that I can move to casting later sounds like it'll be horifically expensive in the prototype stage, and our production will ramp up very slowly (200-ish units in the first 2 years). Thanks for the heads up on the gaskets.

Thanks for the rec on BUD too, I'll take a look.

 

[itsmoked]

Think o-rings!

Keith Cress
kcress -

http://www.flaminsystems.com

 

[drawoh]

itsmoked,

Standard, solid rubber o-rings will be hard to implement on a welded, sheet metal enclosure. O-rings require accurate mating surfaces. They would be possible if the housings were machined from billet, but the OP is correct about his dimensions being too big. O-rings also require a lot of contact force, probably not possible on a box with an acceptably small number of screws. Search Parker's website for information how much force it takes to compress an o-ring.

Whatever fills his gap will have to be resilient enough to account for sheet metal and welding tolerances. A thick enough piece of closed cell foam rubber will work, the first time. It will set upon assembly. Hollow rubber sections are an excellent possibility.

Rubber suppliers can fabricate o-rings out of hollow rubber cord.

JHG

 

[itsmoked]

Typical.... Leave it to a Mech to know more about O-rings!

Thanks for the refresh info drawoh.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[drawoh]

itsmoked,

I have used them to clamp optics. They allow me to design a controlled preload for an expensive piece of glass. They are flexible enough to function through significant temperature changes.

In other words, I have crunched the numbers.

JHG

 

[itsmoked]

I am using an IP65 box in a product. Last night I actually had to start the packaging aspect of the design. This box uses an o-ring.

Sure enough it's tightly constrained inside a groove and the cover has a matching lip that seats down inside the groove onto the o-ring - all pretty high precision.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[drawoh]

itsmoked,

Is it a big casting or a little casting?

Little castings are more accurate than big castings, and the lids probably are more rigid. You can add complex gussets to make them more rigid. You can also make the O-ring fatter, which makes it squishier.

Larger IP65 enclusures use hollow gaskets.

JHG

 

[MadMango]

You don't have to use just o-rings. IP64/65 only needs to protect against dust & water spray or dust & low pressure water spray. With both you are still allowed a small amount of water intrusion, unlike IP66/67. You could use any form of tape-based closed-cell foam with adhesive backing, or something with a closed shape that will conform to the closure lid.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?

 

[itsmoked]

http://www.budind.com/view.php?part=n4x

http://www.budind.com/pdf/hb1334.pdf

It's actually ABS and not very big. 7"x4".

Keith Cress
kcress -

http://www.flaminsystems.com

 

[SteveMartin]

I do this kind of work all the time. Our enclosures are either cast or bent & welded sheet metal, usually sheetmetal. We typically use closed cell foam gaskets for the interface, though we have used o-rings as well. The o-rings are much harder to make work due to the bend and weld tolerances, as has already been mentioned. The number of fasteners on the o-rings tends to be unfortunately high, also.

 

[sreid]

I agree with everyone on the foam strips. See adhesive backed polyethelene foam strips at

http://www.mcmaster.com

P. 3506 such as 93565K73 [1/4" T x 1/2" W].

http://www.mcmaster.com/#catalog/115/3506/=19qsjb

 

[sreid]

Also, use a Gore Vent.

http://www.gore.com/en_xx/products/venting/technical/index.html

 

[drawoh]

sreid,

You can also get rubber vendors to cut gaskets from closed cell foam rubber sheet. This is very cheap, and the sheet can be self-adhesive.

As I noted above, the foam rubber sets upon assembly. If the device is not taken apart, this does not matter. If it is opened and closed regularly, I would recommend not using this.

JHG