Cold wound Vs. Hot wound springs

[KIJIMA]

Could someone please explain the difference between hot wound and cold would springs, or rather the benefit in cold wound silicone wire springs. ie like eibach, and from what I know kings have just started to replicate the same manufacturing process.

So what is the benfit to either manufacturing process, is one better or give a different feel? Also are there any distinct benefits to a progressive wound spring to a more liner wounded spring?

I heard mention of somthing called a 'higher helix angle' but I have no idea what that means. Help!

[Matty]

It's to do with the manufacturing process, the metallurgy and so on. Either method has merits. I'm sure google or wikipedia will have some info.

There wouldn't be any difference from the drivers seat. One may last longer than the other though (but there's many other factors affecting it that you can't make a blanket statement).

The spring shape is a helix. The helix angle is the angle the coil makes to horizontal when it is standing upright. A higher helix angle has less turns in the same height, which means that spring should be able to compress more without binding.

[ndragun]

So what is the benfit to either manufacturing process, is one better or give a different feel?

No difference whatsoever to the end-user...

Cold forming might be somewhat cheaper - since it costs more money to make stuff hot?
Cold formed materials are probably stronger since they'd be work hardened... and would come from an extruded wire with a distinct grain pattern? Hot forming would alter the grain structure........ that could be altered by heat treating the part afterwards, anyway - but again it would be more expensive.


Thats all i can think of

[Benny]

The machinery required to make cold wound springs is far more expensive than the machines that make hot wound springs.

As cold winding is akin to forging, the metal holds its \"springiness\" for longer and won't sag as quickly under H/D conditions as hot wound springs would.

Also, when hot winding springs, the temper of the metal is altered and so it is harder to control the exact spring rates when the springs cool down, so cold wound springs are more equal to each other.

[KIJIMA]

The machinery required to make cold wound springs is far more expensive than the machines that make hot wound springs.

As cold winding is akin to forging, the metal holds its "springiness" for longer and won't sag as quickly under H/D conditions as hot wound springs would.

Also, when hot winding springs, the temper of the metal is altered and so it is harder to control the exact spring rates when the springs cool down, so cold wound springs are more equal to each other.

Thanks for your answers guys! I did a little digging around, and benny you are 100% correct, its dearer to cold wind a sping (like eibachs) but they do prove to be better in the long term ie sagginess over time.

However, it I was told that a novice like me, wouldnt be able to tell the difference in the drive of the two anyway. Im stil lnot fully understanding the helix angle buisness completely, as to what is the most desired helix angle you want, but Im getting a basic idea.

Thanks again.

[Matty]

Re helix angle, if you're trying to achieve the same spring rate you can either have lots of coils of a heavy duty wire, or less coils of a thinner wire.

Obviously the more coils you have (assuming both springs are the same length), the lower the helix angle.

However, more coils of heavier wire will have a greater solid height (ie the height at which all the coils bind), and therefore less available travel.

On the flipside, the more coils you have (of heavier wire) the lower the stress will be in the compressed spring. Minimising stress is important to preventing the spring from sagging.

a higher helix angle also puts more shear stress in the spring.

In a nutshell, lower helix angle is generally better for preventing sagging, but needs to be high enough to prevent binding and minimise weight...