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hydraulic press

hydraulic press

(OP)
I am looking for some advice on a project I am working on. I have designed a hydraulic press and my question is relative to the Aluminum heat platen and steel press plate. There is a 15" L x 6.69" W x .75" thick steel plate (A514 steel) with 15"Lx6.69W" and 10mm thick sheet of insulation underneath (Made from Mica) and a 15" L x 6.4" W x .75" thick Aluminum heat plate. My question is if i wanted to fasten these three plates together (Steel, Insulation and Aluminum) using a bolt in each corner, does this sound like a problem when you take into account the coefficient of thermal expansion between both materials. Also to mention the press is using a 25 ton cylinder, and Al plate will be heated to no more than 230 F.

RE: hydraulic press


Why do you think this is a problem? Better would perhaps be to fasten them together more permanently. Compere to kitchen cooking pans made of steel and aluminium combinations/layers.

RE: hydraulic press

Your bolts will just hold them together, not much force is involved (they are so thin that they would flex easily).
I would leave plenty of clearance in the holes in the Al, and use Belville washers on hard steel washers to provide some clamping force as the temp changes.
Use stripper bolts with smooth shanks, you don't what to have the Al or insulation rubbing against threads.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: hydraulic press

Hi

I think you need to analyse the joint and determine the stresses in the relative materials because if you overtighten the bolts the will possibly come loose. I would start the analysis assuming uniform heating because that at least can be done by hand but in reality you will probably end up with differential heating which is very complicated.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

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