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SEMS fastener???? 2
- Thread starter RUSO
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SEMS is not an acronym, but it is an abbreviation of asSEMblieS, that is, an assembly of a screw and washer.
It was originated by Illinois Tool Works (ITW). ITW does have SEMS licensed with the US Patent and Trademark Office.
Here is some information from the ITW Internet site:
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
It was originated by Illinois Tool Works (ITW). ITW does have SEMS licensed with the US Patent and Trademark Office.
Here is some information from the ITW Internet site:
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RUSO-
A SEMS fastener may also be a combination of a nut and toothed lockwasher. I tend to stay away from toothed lockwashers because:
A. There is no evidence to show that they provide any useful locking for vibration resistance. One fastener consultant I know claims that helical-split and toothed (external and internal) lockwashers not only have questionable value, but they also tend to make the joint less stiff and thus more subject to loosening in vibration.
B. The teeth of the lockwasher tend to break off and float around inside the assembly. If the assembly has electronics within, the tooth can cause problems.
I've found that NyeLock compound or nylon patches (or strips) applied to the external thread are the best to prevent loosening only if placed to fall within the internal thread at the assembly. Self-locking nuts are standard and are available with internal nylon patches.
I hope this wasn't overkill.
H. Bruce Jackson
aka Tunalover
A SEMS fastener may also be a combination of a nut and toothed lockwasher. I tend to stay away from toothed lockwashers because:
A. There is no evidence to show that they provide any useful locking for vibration resistance. One fastener consultant I know claims that helical-split and toothed (external and internal) lockwashers not only have questionable value, but they also tend to make the joint less stiff and thus more subject to loosening in vibration.
B. The teeth of the lockwasher tend to break off and float around inside the assembly. If the assembly has electronics within, the tooth can cause problems.
I've found that NyeLock compound or nylon patches (or strips) applied to the external thread are the best to prevent loosening only if placed to fall within the internal thread at the assembly. Self-locking nuts are standard and are available with internal nylon patches.
I hope this wasn't overkill.
H. Bruce Jackson
aka Tunalover
Reply to Cory really,
Think Tuna Lover, gawd bless him is actually correct on this one. A SEMS is a screw AND washer assembly regardless of the washer being flat, helical, toothed or any other shape. The washer is a separate entity form the nut, hence the word 'asSEMblies'
KEPS is a pre-assembled nut and washer combination whereby the nut and the washer are attached so that they cannot fall apart from one another. The origin of the word 'KEP' comes from the word shaKEProof and the 'S' at the end of 'KEP' being aquired due to the pieces normally being purchased in quantities of more than one.
Both SEM and KEP, (or SEMS and KEPS!) are trademarks of the Illinois Tool Works Inc.
Hope Helps,
Happy Trails,
Jeannie
Think Tuna Lover, gawd bless him is actually correct on this one. A SEMS is a screw AND washer assembly regardless of the washer being flat, helical, toothed or any other shape. The washer is a separate entity form the nut, hence the word 'asSEMblies'
KEPS is a pre-assembled nut and washer combination whereby the nut and the washer are attached so that they cannot fall apart from one another. The origin of the word 'KEP' comes from the word shaKEProof and the 'S' at the end of 'KEP' being aquired due to the pieces normally being purchased in quantities of more than one.
Both SEM and KEP, (or SEMS and KEPS!) are trademarks of the Illinois Tool Works Inc.
Hope Helps,
Happy Trails,
Jeannie
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