Helical spring washers
Helical spring washers
(OP)
I know this has been asked before (http://www.eng-tips.com/viewthread.cfm?qid=103389) but hopefully this time...
What bolt load is required to flatten a Metric helical spring washer? Is it specified in some standard?
Now I know they are considered pretty useless as a lock washer. What I'm trying to find is the load required to flatten them, and consequently if the washer is flattened can we take that to indicate a bolt tension, and how reliable is it?





RE: Helical spring washers
RE: Helical spring washers
"What I'm trying to find is the load required to flatten them..."
My impression from finding them in a variety of devices is they flatten pretty easily, and the tendency for some to tear up the surfaces they touch likely makes future embedment of the joint surfaces pretty likely, to the detriment of the bolt clamping force.
As I recall the inch and metric specs I've seen are purely dimensional.
Like this -
https://mdmetric.com/fastindx/uf32_39.pdf
RE: Helical spring washers
Dick
RE: Helical spring washers
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P.E. Metallurgy, Plymouth Tube
RE: Helical spring washers
MotorCity, they are being used on U bolts to secure antenna poles to mounting brackets. A very common application but I have never found any data on what the connection can carry.
RE: Helical spring washers
Ed's tip about using bellville washers as a tension indicator is a useful one, however.
RE: Helical spring washers
"If you don't have time to do the job right the first time, when are you going to find time to repair it?"
RE: Helical spring washers
Tunalover
RE: Helical spring washers
NASA FASTENER DESIGN MANUAL RP-1228. The manual devotes only a sentence or two to this topic but it's enough to make you question your belief system before using these washers.
Tunalover