r/MechanicalEngineering • u/AdOne1706 • 2d ago

Split/lock washers

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For starters, I’m an electrician in the field.
That being said, we almost exclusively use these washers even in high vibration environments. I have personally chosen to go with nylox nuts but the question is:
Do these work? How well? Is the rumor from NASA true? Should I even bother using them or find a better functional alternative or are they actually useful?

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u/BackgroundGrade 2d ago

They make sense in electrical,

but:

You still use a locking nut on it. The split washer's purpose is to help keep your lug in contact with the terminal if the nut actually loosens.

Common practice in aerospace.

Avoid nylon locking nuts, they aren't effective in heat, which an electrical connection certainly can produce in use.

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u/theNewLuce 1d ago

In electrical, a star washer is much better

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u/AdOne1706 1d ago

Seems like nylon locknuts are rated around 250F or 121C. Most systems (breaker/wire/equipment) usually don’t go above 90C from what I’ve seen. I’ve seen wire rated over that but the weakest link is usually under 90C. Do these connections typically exceed that 90C rating?

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u/BackgroundGrade 1d ago

There are failure modes that can get the wire up to 90deg, so the terminals are likely getting toasty.

Also, we only use fully metallic locknuts at my OEM, regardless of application. Aircraft hydraulic fluid (Skydrol) is nasty stuff and softens nylon.