STRENGTHENING AN ENCLOSURE

[imagineers]

I am designing an enclosure for several components. Total weight of the components with fluid is around 100lbs. the box is around 427mm x 904mm x 173mm. It is a simple box with bent walls and a top bend flange for some strength, but I am a little concerned that maybe the bottom may be kind of weak. What can I do to strengthen this? I have thought about adding punched features in the bottom like ribs, or even a welded l bracket across the box, but I am not sure whether this follows any standard or will be the best and maybe most economical option??

 

[KENAT]

What material & what volumes?

You mention standard - what if any industry standards or safety regulations apply to your application?

My sheet metal vendors tend to shy away from stamped features on low volume stuff due to the effort required to get it right. So welding or riveting reinforcement - if it can't be done with clever combination of bends - seems to be favorite.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[imagineers]

it will be made with SECC steel, pretty much the same material they use on computer chassis.

 

[chicopee]

Thickening the bottom should work. Add another bottom plate with 1" high flanges and spot weld the bottom and the flanges to the side of the box.

 

[drawoh]

imagineers,

How are you attaching things to the bottom? There are a couple of issues here. Your enclosure is big enough that you do not want to be flipping it upside down so that you can install fasteners. You need to follow the recommended DFMA practice of having the tapped hole arranged so that all screws are inserted from above.

Anything mounted to sheet metal should be attached as closely as possible to a folded edge, for strength and rigidity. Large mount flanges on your components help with that.

Consider aluminium instead of steel. Since it is one third the mass, it can be three times as thick. For a given mass, it will be very much more rigid, and you can use captive fasteners like PEM nuts. The usual sheet metal grade here in North America is 5052-H32.

--
JHG

 

[dvd]

How many are you making?
Is there a stress problem, or is it an oil-canning issue?
Is cost an issue?


If it is oil-canning, you could adhere an inexpensive material like heavy roofing felt, or maybe spray rhinoliner on the bottom.

Henkel has a product that may also be of interest.

http://www.henkelna.com/product-search-1554.htm?nodeid=8797992419329

 

[Tmoose]

How is the enclosure supported?
Where are the components located.

Are the components docile and quiet, or buzzing?

Will the tree fall in the woods, or beside the constable's house?

 

[imagineers]

the enclosure will be supported in a server rack with rails on the sides. Pumps inside but nothing that will cause any real vibration. Do not want to use aluminum. good point was mentined about expense for the punching, I may decide to weld a fals bottom type structure into the floor of it. The components are raised about 5mm off the ground anyhow, so this might also work as a piece to secure the components. Volumes will be only about 10-20 a month at this stage not sure if punching strengthening ribs for that quantity makes sense?Thanks for all the response

 

[kjoiner]

Hello,

If the part is being cut on a turret punch, some vendors may have tooling that allows you to roll stiffening ribs or beads into the sheet without dedicated stamping tools. Some of our vendors have that ability and use the technique rather than adding cross brakes on the press brake to prevent oil canning in the larger back panels on our equipment. Another option that is not as pretty is to tack weld stiffening ribs such as angles along the length of the part. what gage is the material?

Kyle

 

[imagineers]

1.5m thick. Currently I have placed a sub back panel inside the enclosure that the components will sit on, similar to a nema enclosure. I think this should offset the weight on the outer box?

 

[Tmoose]

"Pumps inside but nothing that will cause any real vibration."

what type of pump? What's it pumping? What is the piping like, and how is it mounted.
Hard Mount it on a nice big panel and it can create a loudspeaker.