Flat washer direction
Flat washer direction
(OP)
Maybe I missed this in the search, but I didn't see this topic posted before...
Recently, one of the grey beards (or mustache in this case) said to always put a washer on a bolt a certain way. The washers are stamped so often times there is a curve or bow to them and they also have a slight edge where the stamping tool cut through.
I've never heard of this. Is it true that there is directionality to washers?
Recently, one of the grey beards (or mustache in this case) said to always put a washer on a bolt a certain way. The washers are stamped so often times there is a curve or bow to them and they also have a slight edge where the stamping tool cut through.
I've never heard of this. Is it true that there is directionality to washers?





RE: Flat washer direction
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RE: Flat washer direction
If the washer is there to prevent the surface of the part being damaged while the bolt is torqued, then it makes sense you wouldn't want any burrs or similar sharp edges or similar defects in the washer facing the surface to be protected.
That said many washers don't exhibit such a noticeable curve/bow/burr etc. in which case it would be difficult to say which side should go up/down.
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RE: Flat washer direction
thread404-147252: washer selection
The specs that define washers do not make any mention of "sidedness".
RE: Flat washer direction
looking at MS washers in our parts store, they don't show this feature.
RE: Flat washer direction
Our MS washers also don't have this problem.
I didn't think it would matter considering the hundreds, thousands or tens of thousands of pounds of force that a bolt can produce. The only thing I could think of was that the burr might prevent full engagement of the washer and over time and vibration, it would wear away and reduce the preload.
RE: Flat washer direction
Tobalcane
"If you avoid failure, you also avoid success."
RE: Flat washer direction
Regards,
Mike
RE: Flat washer direction
RE: Flat washer direction
Mike Halloran
Pembroke Pines, FL, USA
RE: Flat washer direction
RE: Flat washer direction
RE: Flat washer direction
Some users of TruArc type snap rings consider them "directional" based on the relatively rounded and square edges from manufacturing.
The TruArc literature is more concerned about chamfers or radiuses on abutting part that tend to bend or twist the ring by applying loads offset by the chamfer distance
RE: Flat washer direction
However cheap washers punched out in a progressive die can have quite a roll over at the edge because depending on the material thickness you have to leave a clearance between the punch and the die - usually 6% total on perforations. If you use the washer with the roll over side down against the surface, you will loose some of the contact surface which can be quite significant.
Quite often one die is built to accommodate a wide range of material thickness and so the die is made with a clearance for the thickest material to be punched resulting in a large roll over for thinner materials. Some (cheap) washers look absolutely terrible.
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