SMT Nut, need to guessestimate the max torque

Aug 04, 2015 20 Replies

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B, and a connector wont cut it

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eople mount a spade lug/ring to the nut with a machine screw and a spring w asher

might damage the solder, and I cannot find information on the SMT nut max t orque

e used to use special/custom parts and performing the relevant tests

but their soldering is amateurish, really crappy, along with bad pictures and ugly looking website. I wouldn't use them as a supplier for sure.

ver your head. Even your question is completely backward. The required tigh tening torque, as a function of material and hardware size, is independent of what your soldered nut can withstand. To give you an idea, for steel har dware:

100 years of field experience. Now THAT is something that can be called "cr appy."

You miss the point. We need to find the maximum torque that the SMD nut can tolerate during assembly of wire lug and during life (vibration, service h andling, etc)

Where did you get those numbers and how do you translate those to a termina l resistance value?

From this old reference perhaps:

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The pressure of the screw into the nut is not a defined standard value. The torque applied to a screw inserted into aluminium thread is different from the first time to the following times the screw is used (the screw tapers/ widens the thread, so the torque is less, for self tapering screws)

Moreover, the thread pitch translates the rotational torque into a pressure torque on the lug, so we could use a lower pitch nut to get more pressure torque on the lug

What I really need is a graph/measurement of the pressure torque on a lug v ersus the contact resistance. For example the graph on page 48:

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Above a certain pressure torque the resistance flattens

This reference lists 10N/mm2 as the required pressue per area

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onal_Bolted_Joints.pdf

Cheers

Klaus

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