Corrosion Protection on Torsion Bar Springs

[nlj]

I'm familiar with the usage of tape as a means of corrosion prevention on torsion bar springs but am curious as to what other options are currently used.

I'm familiar with the usage of PVC pressure sensitive adhesive, but have been having issues with corrosion pockets developing and tape degradation, leading to failures. Also, if using tape, what variables should be considered in choosing a proper tape and is PVC a viable option?

 

[patprimmer]

You could paint it with a tough paint like a two pack polyurethane or even a "plastic bumper" grade of PU or a paint designed for steel ship hulls. You could electroplate it with zinc. You could probably even powder coat it with low temperature powders. I suspect you need to know at what temperature your torsion bar starts to lose it's temper and at what temperature the coating needs to be applied or cured.

Regards

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[CoryPad]

For automobile suspensions, the surface treatment of a torsion bar is cathodic electrocoating (e.g., ~ 30 [μ]m of epoxy).

Regards,

Cory

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[Neubaten]

I've heard this rule of thumb from the old people in my factory, regarding suspension parts:

-Microphosphating + cathodic electrocoating if the part is not exposed to impacts from small particles at high speed (i.e. a seat component)

-Microphosphating + powder organic coating for exposed suspension parts, if the part needs to resist a "gravel test" (not sure how it is said in english) where they launch small particles into the part.

 

[CoryPad]

Neubaten provides some good rules of thumb. And, he mentioned phosphating, which is the standard primer for coated steel parts.

For automotive springs, electrocoating is used for lower-cost applications. For higher performance applications, powder coating is used either as a thick single layer, or as a topcoat over an electrocoating basecoat.

Regards,

Cory

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[nlj]

Thank you all for the information.

The application I'm concerned with it for more of a high-performance application in which the torsion bar is under quite high stresses. The fact that in the automotive industry a paint or primer is only needed leads me to believe that perhaps our torsion bar is under-designed. Currently we use the tape for both corrosion protection and also protection against impact of gravel and rock.

 

[Peter7307]

Another method of protection is to use "heat shrink" ; the same plastic wrap material used to protect electrical connections.

This is quicker than tape but the bar must be off the car for it to be done.
For an assembly line it is far to expensive but for a limited production it may be viable.

Pete.