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screw torque/clamping pressure

screw torque/clamping pressure

screw torque/clamping pressure

(OP)
Hello,
The problem I am having is this:

I have a 3"x3" soft aluminum plate clamped on each corner with a screw.  I need to know how to find the pressure the plate is transfering to the surface below.

If anyone has any hints on how to do this I would appreciate it.

Thanks,

RE: screw torque/clamping pressure

If you know the plate thickness t, screw head outer diameter d1, and screw pretension F, then you can calculate the pressure p per screw.

Assume the force spreads out from the screw head into the Al plate with a 30 degree angle.  This means the effective diameter d2 under the Al plate is:

d2 = d1 + (2t)/√3

Then

p = F/A

where

A = (π·d22)/4

RE: screw torque/clamping pressure

gopalka,

   How accurate do you have to be?

   You have not indicated the size of the screw, or the specified torque.  I have seen literature on how to predict how people will install fasteners without a specified screw torque, but boy is it approximate!

   Even the standard screw torque methods are approximate.

                          JHG

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