Proper Use of Spring Lock Washers
Proper Use of Spring Lock Washers
(OP)
I am looking into the proper use of spring lock washers. We have a few applications where we use them, but are having them split open while tightening. One concern is that lock washers are basically useless when torqued down until it becomes flat. Does anyone have any information on this?





RE: Proper Use of Spring Lock Washers
075-5.6.2 HELICAL SPRING LOCKWASHERS. The most frequently used lockwasher is the helical spring(split) type. The helical spring lockwasher (Figure 075-5-11) is flattened when the bolt is torqued down. Once compressed, it acts as a flat washer, contributing normal friction between the nut or bolt and the bearing surface during tightening. If the fastener clamping load relaxes, the spring action of the lockwasher will maintain some load between the threads of the fastener, reducing the tendency of the fastener to rotate. Some helical spring lockwashers have a sharp tooth on each end that bites into each bearing surface and prevents rotation. This type adds friction during tightening and will result in some reduction in preload. Because the helical spring lockwasher diameter is small and it tends to dig in when loosened, it is rarely used on soft materials or with oversized or elongated holes.
You may also want to check to ensure that the lockwashers are the same grade as the fasterns, which may be the cause of them opening up during tightening.
RE: Proper Use of Spring Lock Washers
RE: Proper Use of Spring Lock Washers
Unless your application is in a thermally dynamice or a varying load environment, and you have enough bolt stretch, you probably don't need lock washers anyway.
RE: Proper Use of Spring Lock Washers
RE: Proper Use of Spring Lock Washers
thread108-114051: Split Washer Placement
thread404-230741: Studies on the use of lock washers?
FAQ404-1257: Is a lock washer an effective torque retention device?
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Proper Use of Spring Lock Washers
http://www.eng-tips.com/viewthread.cfm?qid=161524
and an FAQ:
http://www.eng-tips.com/faqs.cfm?fid=1257
I couldn't find the link to the NASA paper on the subject... but there is one out there.
-Dustin
Professional Engineer
Pretty good with SolidWorks
RE: Proper Use of Spring Lock Washers
Page 9 references the lock washers.
Use of system voids warranty.
RE: Proper Use of Spring Lock Washers
RE: Proper Use of Spring Lock Washers
Split lockwashers were used practically forever by the OEM, and hotrod aftermarket.
http://go.mrgasket.com/ProductImages/500/910.jpg
http://go.mrgasket.com/ProductImages/500/911.jpg
A friend just bought some premium clutch bolts for his 1976 Corvette, made by ARP.
The ARP bolts came with flat washers with a heavy ID chamfer on one side to more than clear the bolt head radius.
http://pe
I would not really expect a problem with either style washer if torqued to the meager 35 lb-ft usually recommended for those 3/8-16 clutch bolts, but would strongly prefer the flat washers in applications where I was serious about loosening or fatigue from lost preload due to a few thousandths of embedment into a murdered surface (which is almost always).
RE: Proper Use of Spring Lock Washers
What grade of bolt and washer are you using? Can you test the hardness of the washers? I have heard of counterfit bolts but not washers.
RE: Proper Use of Spring Lock Washers
RE: Proper Use of Spring Lock Washers