What You Should Know about Spring Washers?

Spring washer mainly is used to prevent the nut from loosening, which is placed under the nut, widely used in the load-bearing and non-load-bearing structures of general mechanical products, which are characterized by low cost, convenient installation, and suitable for parts with frequent assembly and disassembly.

spring washers

Main Functions of Spring Washer

The most basic function of the spring washer is anti-loosening, which is to give force after the screws and bolts are tightened. It can add a friction force between the screw bolt and the material. Thus, the material can be tightened during vibration to prevent loosening between the screw bolt and the material. The slotted hex nut is specially used with the bolt with a hole at the end of the screw to insert the cotter pin into the hole of the screw rod from the slot of the nut, preventing the nut from loosening automatically. It is mainly used for occasions with vibration load or alternating load.

Another function of a spring washer is to cooperate with three assemblies of screws and bolts, which are also used together with flat washer.

spring washers

Working Principle of Spring Washer Anti-loosening

The anti-loose principle of the spring washer is that after it is pressed flat, the spring washer will produce a continuous elastic force, which will keep a friction force between the nut and the threaded connection pair of the bolt, generating a torque to prevent the nut from loosening. At the same time, the sharp corner at the opening of the spring washer is embedded into the surface of the bolt and the connected piece respectively, so as to prevent the bolt from rotating relative to the connected piece.

Types of Spring Washers

Wave Spring Washers
Wave spring washer is divided into WG type, WL type, WN type

spring washers

WG type and WL type wave washer
WG type and WL type wave washer are open spring washer, which can usually be installed in a small space, such as applying prestress to the bearing, reducing the noise of bearing operation and improving the operating accuracy and stability of the bearing. In addition, there are also a large number of application in electronic appliances. The materials include carbon steel, stainless steel, copper alloy, etc.

WN type wave washer
WN type wave washer is multi-layer wave crest overlapping spring washer. Compared with WL type, this series is composed of multi-layer materials and is applicable to the situation where the elastic force is large and the elastic force release is required to be uniform throughout the working stroke. 

Disc Spring
DIN6796 Disc spring washer
DIN6796 disc spring is a lock washer used for bolt and screw connection. It is designed and manufactured according to DIN 6796, and is applicable for the connection of medium or high-strength bolts and screws. The bearing load is large and the elastic recovery force is strong. The bolt tension can withstand the wear, thermal expansion, contraction of wear parts, or the compression of seals. Disc spring washer can effectively replace ordinary spring washer, but it is not suitable for combination of lock washer and flat washer. Because it is a disc spring that can be folded, which can increase the amount of deformation and the spring force. The ideal installation method is to flatten as much as possible. The closer to the flattening state, the faster the tensioning torque increases. The appropriate bolt tension can be obtained without the need for a torque wrench.

spring washers

Internal Tooth Spring Washer And External Tooth Spring Washer

There are many sharp elastic warping teeth on the circumference of these two spring washers, which can be pressed on the bearing surface to prevent the looseness of fasteners. The internal tooth elastic washer is used under the screw head with a small head size. External teeth spring washers are mostly used under bolt heads and nuts. The toothed spring washer is smaller than the ordinary spring washer and the fasteners are evenly stressed with reliable anti-loosening, but it is not suitable for the parts that are often disassembled.

spring washers

Causes of Spring Washer Breakage

1. The expansion ring of the spring washer
2. The expansion ring of the spring washer must be subject to a radial outward tension, which is derived from the tightening axial force generated by the tightening torque.
3. The external chamfer of the nut-bearing surface makes the axial clamping force produce a radial component, which makes the opening of the spring washer expand. The smaller the chamfer diameter, the greater the possibility of the expansion ring.
4. Adding a flat washer between the nut and the spring washer will help to slow down or prevent the occurrence of an expansion ring, but the flat washer is too thin or too soft to prevent the occurrence of an expansion ring.
5. The hydrogen embrittlement of the spring washer is generally caused by an unreasonable heat treatment process and failure to conduct hydrogen removal treatment timely after Zinc electroplating.


This article mainly introduces useful knowledge of spring washers, including their main functions, anti-loose principle, various types, etc, which can help people better use spring washers.

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