solid length

[EngJW]

I have been using total number of coils (N) times wire diameter (d) to get solid height. This appears too conservative for our application. We are trying to pack more spring into a limited space. We have been able to add several shims to the existing spring, which calculations say there is no room for.

The spring is squared and ground on both ends. Would it be more reasonable to assume half a coil is lost on each end, so that the solid height would be (N-1)d?

Thanks,
John Woodward

 

[TheTick]

Have you considered a tapered or barrel-shaped spring profile?

 

[desertfox]

Hi jlwoodward

It is usually according to the british standard for compression springs to allow one dead turn at each end of a spring with ground and squared ends. However according to Mechanical Springs book by Wahl, practical tests show dead turns to be between 7/8 of a turn and 1 turn at each end with an average of 1.85 total dead turns. Be aware that if you compress the spring to much it might take a permanent set and the spring rate will not be linear after 85% of its
of its total compression is reached.

regards Desertfox

 

[israelkk]

Can you give more info what are exactly the requirements from the spring i.e. maximum outside dia, maximum working length, force at working length, wire material, type of use (static or cyclic) etc.

Some times depends on the spring geometry you can use less than 2 dead turns however it depends on the geometry. You could also use preset (scragging) to get more from the spring.

 

[israelkk]

jlwoodward

In addition to my previous response, I recall that years ago I consulted for design of a compression spring where the number of dead coils was 1.6 instead of 2. However,more info of your design requirements is required.

http://www.webspawner.com/users/israelkk/index.html