need to determine proper run down speed for stainless steel lock nuts
need to determine proper run down speed for stainless steel lock nuts
(OP)
Does anyone have data on determining the proper run down speed for stainless steel lock nuts to avoid galling? Using a DC Electric nut runner.





RE: need to determine proper run down speed for stainless steel lock nuts
Regards,
Cory
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RE: need to determine proper run down speed for stainless steel lock nuts
RE: need to determine proper run down speed for stainless steel lock nuts
Mike Halloran
Pembroke Pines, FL, USA
RE: need to determine proper run down speed for stainless steel lock nuts
Galling would be more likely at 10 rpm or 1000 rpm. I don't think a tweak on your current speed will do much.
Regards,
Cory
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.
RE: need to determine proper run down speed for stainless steel lock nuts
Mike Halloran
Pembroke Pines, FL, USA
RE: need to determine proper run down speed for stainless steel lock nuts
"How To Stop Thread Galling On Stainless Fasteners"
http://www.marfas.com/gallingofstainless.htm
Fastener expert Joe Greenslade claims:
" Slowing down the installation RPM speed will frequently reduce, or sometimes solve completely, the problem. As the installation RPM increases, the heat generated during tightening increases. As the heat increases, so does the tendency for the occurrence of thread galling."
RE: need to determine proper run down speed for stainless steel lock nuts
http://www.marfas.com/gallingofstainless.html
RE: need to determine proper run down speed for stainless steel lock nuts
RE: need to determine proper run down speed for stainless steel lock nuts
A common problem with deformed thread, self locking nuts is that the prevailing torque (ie. thread interference) tends to vary widely with the smaller thread sizes. The deformed thread locking feature is suppose to be within certain limits for running torque, but they never are. So I would check the running torque on a representative sample of the nuts you are using.
300 series austenitic cres alloys(with the exception of 303, which should never be used for a fastener) are the most prone to galling, likely due to their work hardening characteristics. Most high quality aerospace cres fasteners are heat-treatable alloys like A286 or 13-8ph, which are less prone to galling. One thing that also really seems to help prevent galling is to have a difference in hardness between the two mating parts.
RE: need to determine proper run down speed for stainless steel lock nuts
Why should 303 never be used as a fastener?