Softening Coil Springs on Car Hood 1

[motorquest]

Greetings,

I'm working on a project where I've been asked if it's possible to heat and quench a coil spring to soften the spring action (i.e., the coil spring is used to raise and lower a car hood). Currently, the springs are too strong and require too much initial effort to lower the hood [which is fiberglass] to the point where it can be lowered easily (Once the hood starts to lower, there's no problem.

The client wants to heat the springs with an acetylene torch then immediately quench them in the hope that this will weak the spring sufficiently to reduce the initial load required to pull the hood down.

My concern is that by heating then quenching the spring, he will make it stronger and more brittle. Any assistance would be greatly appreciated.

Regards

 

[israelkk]

I am sorry but this not the way!

First of all what kind of spring are you dealing with?compression, extension etc.?

What is the material the spring is made off? Not all spring materials are heat treatable many of them recieve their propery by cold working (i.e. music wire, cold drawn etc.)

Spring manufacture is a delicate and inelligent process which should not be taken lightly. Heat treating is also a science and sometimes even an art and should be left for the experts.

The spring constant is a property of the material i.e the young modulus and the spring dimensions. Therefore, the force of the spring is the function of the deflection multipled by the constant and not how strong the material is. However, if the wire is too weak the spring will have a permanent set and will change its dimensions after it is fully or partially loaded or will break by fatigue after mutiple hood lowering and raising.

The only proper way is to design a new spring and not vandalize an existing spring without the proper facilities and uncontrolled processes.

If your facility can not properly design and analyse the best spring for the project you should seek a help from an expert.

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