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When to use Flat washers and lock washers Question
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Posted by: RickP330

08/07/2007, 16:58:26

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Hello All,
Can you tell me if there is a quick reference as to when to use Washers and Lockwashers? It drives me nuts when I see a split lock washer specified over a flat washer. Is there any sense to that? I really don't think so, but I have no external references that say otherwise so it is just my opinion. I would think that the flat washer would negate any locking effect of the split washer, but like I said I would like to reference some sort of design guide.
TIA
Rick







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Re: When to use Flat washers and lock washers
Re: When to use Flat washers and lock washers -- RickP330 Post Reply Top of thread Forum
Posted by: Kelly Bramble

08/07/2007, 18:06:55

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I'm not sure if there is an official industry standard design guide on when to use or not use washers.

In general, I use a flat washer under a split locking washer to protect the base material, plating, or coating from damage caused by the split washer action. I may also use the flat washer to distribute the fastener load or ensure the split washer does not fall or grind into a larger clearance hole feature. Damage caused by the washer could cause corrosion or fatigue cracks.







Modified by Kelly Bramble at Tue, Aug 07, 2007, 18:08:49


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Re: Re: When to use Flat washers and lock washers
Re: Re: When to use Flat washers and lock washers -- Kelly Bramble Post Reply Top of thread Forum
Posted by: chaulklate

08/07/2007, 18:15:10

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Rick,

I'm with you, I believe using the 2 together negates the locking effect. In my opinion, it's ok to use the flat washer beneath the bolt head (for whatever reason you might want to do that), but I feel the lock washer should only contact between the nut and the 'parent item' that is being bolted. Of course, I have nothing to back that up with other than my own personal history, nor am I a structural or hardware specialist.

I would like to hear other opinions and experiences on this topic.








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Re: Re: Re: When to use Flat washers and lock washers
Re: Re: Re: When to use Flat washers and lock washers -- chaulklate Post Reply Top of thread Forum
Posted by: Kelly Bramble

08/07/2007, 18:41:05

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I agree that when the split lock washer digs into the base material it is likely to hold better. However, the split lock washer will exert force on the bolt/screw head as well by compression. This will in most cases prevent the fastener from backing out as well.







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Re: Re: Re: Re: When to use Flat washers and lock washers
Re: Re: Re: Re: When to use Flat washers and lock washers -- Kelly Bramble Post Reply Top of thread Forum
Posted by: jboggs

08/08/2007, 11:11:35

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I think SME and other organizations (of course the military too) have done studies and published "standards". As for me, I ALWAYS use a flat washer when bolting through a slot. For what its worth, in 30 years I haven't seen any negative effects of using both flat and lock washers together.







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