Talk:Washer (hardware)

Duplicate notes?
It looks to me like notes a and b (re: failing lock washers & BMW) are both referencing the exact same publication (and pages, and comments thereon), with different wording and the titles shuffled around. Aside from a little more detail on applications, a little more tortured grammar, and a [citation needed] sticker, the second seems to be functionally identical to the first. Or am I missing something?


 * &mdash;73.17.158.98 (talk) 20:40, 29 August 2016 (UTC)

Some heartburn here...
The statement in the lock washer section is misleading: "This type of washer is especially effective as a lock washer when used with a soft substrate, such as aluminium or plastic,..".

Use of lockwashers on soft materials like plastic is only recommended when the lock washer is placed between the screw head and a flat washer. A lock washer (of any type) bearing directly onto a soft surface is quickly made pointless by the soft material's creep or deformation under pressure. In this case, if a tooth washer is used against plastic, the tooth washer quickly becomes embedded in the plastic and any preload required to provide the locking (against the screw head) is gone. A tooth washer is effective as a lock washer only when it is placed between relatively 'hard' materials. In any case, lock washers and plastics are always subject to creep which in many cases results in at best a minimal locking effect. I'll not edit the text immediately so as to providce some time for comments. Ken (talk) 22:18, 27 January 2014 (UTC)

Aren't belleville washers lock washers too? I added Fender washer, but I'm not quite sure how to define it. Ortolan88 00:10, 22 Aug 2004 (UTC)


 * Yes, belleville washers are somtimes used as locking devices. But only in joints with low dynamic loads. A proper pre-load (or clamp-load) is one way to keep a bolted joint from coming loose, but belleville washers usually have lower pre-loads than bolts (1/4" grade 8 capscrew will have a pre-load of about 2800 lbf, and belleville washers for 1/4" hardware might have a compressed load of 50-1000 lbf).


 * Bellevilles are also used as pure springs. One example is a live load joint, where flexibility is designed in. In this case bellevilles are springs, maintaing a pre-load, but not working as the locking mechanism.


 * Another example is a joint that experiences a lot of thermal expansion and contraction. A belleville may supply the designed pre-load, but the bolt may have an additional locking mechanism (loctite, for example) that would fail without the belleville.


 * A fender washer is a flat washer with an oversized O.D. This type of washer distributes the capscrew's clamp-load over a greater area.

209.102.125.87 01:47, 22 Aug 2004 (UTC)


 * Tab-washers and cup-washers are also used for lock washers, but usually need modification of the part and sometimes the fastener. &mdash;Dmc6006 20:08, 22 Aug 2004 (UTC)

Just for the record, I knew what a fender washer was, I just didn't know what to say about it. I suppose the name is simple, "that which fends, or protects". Ortolan88 20:18, 22 Aug 2004 (UTC)

There is acommon British name for fender washers that I've heard but have forgotten, anyone know?? Pud 00:20, 23 Aug 2004 (UTC)


 * Mudwing washer ? Penny washer ? 213.41.173.68 (talk) —Preceding undated comment added 08:10, 13 October 2010 (UTC).

More detailed description needed
It would be useful to have an explanation of which circumstances, for instance, a washer is not needed.

I'd suggest adding pictures of washers in use. Incredibly, this page does not have even one such picture. Hardware dufuses such as myself want to know which side of the connection the washer goes on (without having to guess). - 24.17.218.38 (talk) 20:21, 30 October 2010 (UTC)ATBS

I'd also like to see an explanation of what a lock washer is... it's not evident!

(And perhaps an explanation of when to use just a lockwasher, and when to use a lockwasher and a normal flat washer as well?) Jo5n 07:22, 12 September 2006 (UTC)

Also, why are they called washers? Were they once used to wash things or something? —Preceding unsigned comment added by 71.35.250.121 (talk) 04:05, 8 October 2008 (UTC)

Phenolic?
Phenolic is not a type of washer; it's a material. —The preceding unsigned comment was added by Special:Contributions/ (talk)

Split washers, locks etc
Firstly split washers are used as springs in rail fasteners -that's millions (or hundreds of thousands) of devices, also a split washer doesn't act as a lock (very well) without special designed bolt and fixing .. I get the point about friction etc - but it's not a true locking spring.

Also the Belleville washer is definately a see also, not a main link - there are other types. Probably the article needs extra work rather than juggling.Sf5xeplus (talk) 18:13, 20 September 2010 (UTC)

I could be confusing usage .. I wasn't aware that smaller spring washers are often sold as lock washers.. I'm more familiar with real ratcheting springs.

Could do with some references, these  are amusingly dismissive of spring washers as lock washers. But it does depend on the application a lot.Sf5xeplus (talk) 18:35, 20 September 2010 (UTC)


 * Yeah, I was going to use the latter as a ref for this article. I have always seen split washers listed as lock washer; in addition to the above ref, see . Please elaborate on their use in rail fasteners, because I'm unfamiliar with that. Wizard191 (talk) 20:22, 20 September 2010 (UTC)
 * Actually I think I mis-remembered about rail-fasteners - what I was thinking about are actually flat profile helical springs, not washers, because they're more than one turn. My mistake.
 * If I get chance I'll expand the article later if someone else doesn't. They way I'd do it it to have a section for each washer type and say if they are used for springing, and or locking, rather than trying to put (spring lock washers) in one of the two sections.Sf5xeplus (talk) 18:35, 21 September 2010 (UTC)


 * I;ve added some more refs, and split those which are grommets. I also changed the formatting to using bold for washer types, rather than having lots of little sections... Please improve.87.102.36.105 (talk) 21:12, 21 September 2010 (UTC)

Reprise of this topic

 * Is anyone up for seeking out some engineering research on the effectiveness of lock washers? The opinion of the one author referenced [see Sf5xeplus's comments above] doesn't seem to carry as much weight as an industry that consistently uses locking washers (spring or otherwise). Looking at the two refs Sf5xeplus quotes, the argument presented against locking washers is more an appeal to common sense (and perhaps the authors experiences, though he doesn't actually claim that) rather than engineering principles backed up by tests and experiments.. Drevicko (talk) 03:49, 28 September 2011 (UTC)


 * I don't have much worth adding here right now, engineering-wise, but I just wanted to mention that aircraft engineers must have found lock washer performance unsatisfactory in some cases over the years, because in some fastener applications they go to such expense with bothering to cross-drill the bolt heads and wire them (against rotation) with stainless steel wire. I think the question may be, *how much* vibration is expected in the particular application, and how safety-critical is that application? I bet lock washers are plenty good enough for many applications, and they spare the expense of doing anything more elaborate in those cases. So they have a little of both sides—adding real value in some applications, and showing inadequate performance in other apps. Forgive me if this entirely non-evidence-based comment doesn't really add anything that wasn't already said. I just had this thought off the top of my head and shared it FWIW. — ¾-10 23:52, 30 September 2011 (UTC)


 * One reason that they MAY be out of favor is that in aircraft, the materials being clamped are usually aluminum. Hard steel (or hard whatever) will eventually cause the aluminum to creep (or displace) because of the force, and once displaced the locking force is relaxed and therefore nil. Dreviko's request for experimental data on this is likely non-existing because no one at least in my industry will argue with this... And we engineers rarely have budgets prove the obvious. We typically do not use them in the electronics industry for mounting printed circuit/wiring boards for that reason. Ken (talk) 21:13, 19 November 2014 (UTC)

One point: The statement "A split washer or a spring lock washer is a ring split at one point and bent into a helical shape. This causes the washer to exert a spring force between the fastener's head and the substrate." is false. Once compressed, a split washer DOES behave like a flat washer. Any 'spring force' in any washers in a joint will simply be a reaction force to the bolt preload, regardless of splits/material/helical shape etc. Sprung washers can _only_ have an effect on a joint when they become partially loosened, as seen extensively high amperage copper 'bus' joints where thermal expansion causes a bolt to lengthen. Very stiff disc springs can then be used to maintain approx clamping force while the bolt is in it's lengthened state. — Preceding unsigned comment added by Cnoj (talk • contribs) 21:49, 23 January 2012 (UTC)

More on lock washer misnomer:

NASA Fastener Design Manual RP-1228, March 1990: "The lockwasher serves as a spring while the bolt is being tightened. However, the washer is normally flat by the time the bolt is fully torqued.  At this time it is equivalent to a solid flat washer, and its locking ability is nonexistent.  In summary, a lockwasher of this type is useless for locking."

Quote (ASME B18.21.1): The ASME also has a standard for lock washers. In that standard it states: "The word lock appearing in the names of products in this standard is a generic term historically associated with their identification and is not intended to imply an indefinite permanency of fixity in attachments where the fasteners are used."

Engineer Gerhardt Junker first tested split 'lock' washer effectiveness and published in late 1960's. — Preceding unsigned comment added by 71.80.117.184 (talk) 15:29, 26 January 2012 (UTC)

I do not think the design intent of split lockwashers are truly understood by most mechanical engineers. The obvious function seems to be to compress where the open ends meet. However the benefit lies in the trapezoidal shape of the washer. As Bickford explains (An Introduction to the Design and Behavior of Bolted Joints, Third Ed, p561) as preload increases to a level many times required to flatten it, the washer will roll and twist. This secondary spring rate dominates the spring rate of the bolt. Therefore a split lock washer can allow the bolted joint to take the same amplitude of vibration while maintaining more preload, which will result in a joint more resistant to loosening. I know that ASME B18.2.1 2009 does require the lock washer to be trapezoidal in shape. I assume the related DIN/ISO/JIS standards do as well. So a split lock washer could be effective in situations where the bolt is required to be relatively short, and a higher preload is desired. I propose this be added as a counterpoint to the NASA quote, or the quote be removed and the Bickford reference replaces it. — Preceding unsigned comment added by CMB042 (talk • contribs) 17:46, 21 December 2016 (UTC)

Toothed washers
Removal, See below:

This maintains tension and opposes any loosening influence on the fastener. The flexed teeth absorb shock, vibration and slipping.

Internal tooth washers have the teeth pointing inward. They are used when the finished appearance requires that the teeth be hidden under the head of the screw, or to avoid the teeth scratching or snagging. Also used with screws with smaller heads. External tooth washers have teeth pointing radially outward. They are used when finished appearance is less crucial as it provides the greatest torsional resistance and therefore locking efficiency because the teeth are on the largest radius. Combination tooth washers have teeth on both sides. They are used when a larger bearing surface is required. It is also often used when there is an over-sized hole. Countersunk external tooth washers are used with Flat Countersunk or Oval Countersunk Screws with angles of 82 or 100 degrees.

These are too close to, or are copied from the references. Can't use as is.Sf5xeplus (talk) 16:38, 13 October 2010 (UTC)


 * Thanks for the heads up. I reworded it to fix the copyvio problem. Wizard191 (talk) 16:41, 19 October 2010 (UTC)

Why are washers called washers?
Why are washers called washers? --78.52.160.147 (talk) 18:23, 15 January 2011 (UTC)


 * I added a short blurb about it in the lead. Wizard191 (talk) 20:40, 15 January 2011 (UTC)
 * I think I first learned about washers when I was about four, as the ones that go on washing machine hoses. It then seemed so obvious, but now I doubt that it related at all. Gah4 (talk) 21:17, 11 February 2022 (UTC)
 * I think I first learned about washers when I was about four, as the ones that go on washing machine hoses. It then seemed so obvious, but now I doubt that it related at all. Gah4 (talk) 21:17, 11 February 2022 (UTC)

Other types
Square washers up to 70mm or so, are often used in masonry work. Tapered washers are commonly used in conjunction with structural steel beams, to match the taper of the flanges of the beams. — Preceding unsigned comment added by Suma rongi (talk • contribs) 07:05, 27 April 2011 (UTC)

Rondelle
I was redirected to this article from Rondelle. There's no mention of Rondelle here. Opbeith (talk) 14:58, 25 September 2012 (UTC)
 * It's the French term for washer, apparently. Is there another definition that you're aware of?Kortoso (talk) 19:44, 5 June 2015 (UTC)

Serrated washer and "star" washer
These are NOT the same thing!!

A serrated washer has serrations on the face of the washer. A star washer has prongs which project radially (or, sometimes, point inward radially).drh (talk) 18:16, 22 July 2015 (UTC)


 * Sometimes both are true simultaneously (radial teeth that are twisted up at the tip). But yeah, I'm sure you're right that the coverage could be expanded or improved. — ¾-10 01:30, 23 July 2015 (UTC)

Nord-Lock and "Delta Protekt"
I just learned of a product called "Nord-Lock" (which Fastenal (a distributor of fasteners) also calls "Delta Protekt", though they also use that term for another product with apparently less thoroughly engineered features of similar concept). My brother sent me a link to a YouTube promo video that I found entirely compelling. I assume they have the same information in a more appropriate reference form on their own site, but I haven't spent any time to find it. The tests shown seem to me to be rigorous and the results possibly encyclopedic?? At the very least I would say that the product or product category should be added to this page, as there is currently nothing even close listed here. I wish I had the time (and, even better, experience doing so) to research and write it up myself, but I simply do not so I'm putting this out there in hopes that someone else can. — Preceding unsigned comment added by 64.55.128.122 (talk) 15:27, 12 April 2017 (UTC)

What's the ethymology? Is it a name?
109.67.32.70 (talk) 04:11, 24 August 2019 (UTC)