How do dimension a compression coil spring?

[Tarator]

Hi all,

I am trying to dimension a compression coil spring... I guess my first question is: do we need to GD&T it? If we do, then what would be the right way... My application is the spring is in a cylinderical pocket (around the OD) and there is a pin goes through the ID.. Free length is about 19mm, OD is 2.9, ID is 1.9.. To me OD or ID can be the primary datum (I would prefer OD for simplicity).. then the other diameter would be controlled with position call-out for co-axiality.. i'm not sure if i need a secondary datum.. the ends are closed and not ground... so they are not really "flat".. not even sure if they need perpendicular control to the primary datum... any suggestions or feedback?

Thank you.

 

[CheckerHater]

If your spring has ground ends, you could possibly specify parallelism in free state, but I wouldn't go any further then that.

Tolerance is usually applied to OD, but if spring has to fit over rod, toleranced ID is appropriate.

Besides "functional" requirements chemical composition and testing parameters are often specified.

The most recent standard ASME Y14.13M-1981(R2003) - Mechanical Spring Representation is currently withdrawn and not replaced.

So I guess any respectable reference book like Genium manual is a fair game.

Good luck!

 

[Tarator]

Thanks for your input CheckerHate!

 

[3DDave]

SAE-AS13572 is still going. $70.
Springs, Helical, Compression and Extension.

Probably best to deal with the spring supplier for specifics.