Your result

Locking ability

Not 
applicable

Reusability

4 out of 5

Worker safety

4 out of 5

Initial cost

low

Lifetime cost

high

SCALE:    0 = Not Applicable.   1 = Unsuitable.   5 = Excellent.

How did we calculate?

Are plain washers effective
against bolt loosening?

Plain washers, also known as flat washers, are the most common type of washer. Plain washers do not have a locking function, rather they are used to protect the mating surface from damage. They do this by increasing the surface area in order to help distribute the load, in particular on soft materials or over large or slotted holes. Plain washers are installed between the bolt head/nut and the mating surface. The bolted joint is then tightened in the same way as an unsecured bolt.

Scroll down to access the eBook "Why do bolts loosen?"
(A comparison between common bolt securing options)

Do you experience bolt loosening? Plain washers have no locking function!

The biggest challenge for a bolted joint, causing it to lose preload and fail, is spontaneous loosening. Vibrations are everywhere.


This test shows how all 3 unsecured joints all rotated loose. A steep decline in the graph indicates a failure.

This Junker test shows how all 3 unsecured joints all rotated loose!

(The Junker test is the most severe vibration test for bolted connections. The bolted joint is exposed to transverse movements underneath the bolt head or nut, while the clamping force is continuously measured.) 
The effectiveness of different locking methods can easily be compared.

 

 

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Which bolt locking product should I use?

See how different bolt locking products perform.

What you will find in the eBook:

  • Pros and cons of the different bolt locking methods
  • Evaluation of different products
  • A print-friendly Guidance for Selection, to help you decide which product to use in your applications

 

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