Are there any chemists, physicists, or mettalurgists around?

[monkeyboy]

I have a question: does keeping a spring compressed cause it to become less "springy" over time? In other words, is there a right way and a wrong way to store a spring, especially one in a spring-loaded device?

[DrWeird]

1. Yes, I believe it does.

Reason? Metal fatigue I'd imagine. Wait for a metallurgist. The solution would be to not store the spring compressed.

[TXlib]

2. Yes, keeping it under compression will cause it to lose some springiness.

In short, the reason is sort of metal fatigue.

But metal fatigue would more properly define the result of repeatedly stretching and unstretching the spring.

You get lattice dislocations in the crystalline structure of the metal. Being compressed will do that, too, but it will be a larger effect the warmer it is.

[Don_G]

3. Yes, Metal Fatigue

The steel has a definate grain and will assume the shape if compressed over time. The cheaper the steel, the faster it will loose it's compressive strength.

Mechanic here.

[Kolesar]

4. Yes,so shift your derailleur to the smallest cog on your bike when done

When storing your bike overnight or over the winter, shift to the smallest cog so that the derailleur spring is extended or "relaxed". Modern bicycles have weaker springs so they shift more responsively. If you compress them, they will get squashed in time.

[Kolesar]

5. Heat will make the spring fail sooner, too

Heat on a compressed spring will reshape it.

[forgethell]

6. I wouldn't think so.

The phenomenom where a metal undergoes a time-dependent strain under stress is called "creep". In metals it is not significant below about 40% of the absolute melting temperature of the metal. This is much hotter than you would care to be around.

However, if the rest position of the spring is such that the coils are not lying together, then if you compressed it, it might be possible to cause "yielding" to take place. But that would take place during the act of compressing the spring, not during storage.

For materials other than metals, the analogous creep phenomenom has different mechanisms, and can occur at room temperature. A strecthed rubber in a prime example.