Joe,

Your last paragraph really sums it up.  All hardware should be torqued for uniformity.  In the case of self locking nuts, of any kind, the run down torque must be added to the desired locking torque.

A torque setting tool will be more repeatable that hand tight.  Consider the assemblers, the petite female assembler that struggles with 20 inLb will tighten things differently than the husky male assembler.  Consider an electric or air driven torque driver.

My 2¢.

Phil Nutting
Design for Manufacturing Engineer
Kaiser Systems, Inc.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Macko
Sent: Tuesday, September 28, 2010 4:23 PM
To: [log in to unmask]
Subject: [TN] Torque or Hand-Tighten Self Locking Nuts?

All,



I would like to hear some comments on the validity of torquing
relatively small "self locking" type nuts used for electronic assembly.
Some think that self locking type nuts should only be hand-tightened due
to the measurable run down torque involved and other think that even
these types of fasteners should be torqued.



The self-locking feature on deformed type nuts for example presents a
measurable run down torque which should be added to the specified
fastener torque value to obtain I would think the correct adjusted
fastener torque value required.  Comments / experience?   thanks



Best Regards,

-Joe




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