Gold Plating on Spring
Gold Plating on Spring
(OP)
I need to spec an appropriate MIL-SPEC-45204C gold plating to go over a Beryllium copper spring C172. The spring is going against a housing that is also gold plated so we are worried about galvanic compatibility. What would be the correct type, grade and class? How do you usualy come up with this data?
Thanks
Thanks





RE: Gold Plating on Spring
RE: Gold Plating on Spring
RE: Gold Plating on Spring
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada
RE: Gold Plating on Spring
RE: Gold Plating on Spring
RE: Gold Plating on Spring
RE: Gold Plating on Spring
"The spring is going against a housing" What do you mean by that? Is it just touching the housing or it is rubbing against ? If it is rubbing, is it an occasionally contact or continuously rubs and in what linear velocity? Is it a connector type product of a slip ring/motor type product? etc. If the spring made of strip or wire?
If it rubs against the housing the harder grade seams to be the choice (for the spring and the housing).
As to the "electrical engineer specs the maximum resistance allowable by the spring" does it includes the contact electrical resistance which is crucially depends on the contact surface pressure between the spring and the housing. Too much pressure will lower the life cycle of the gold plating. Too low will create more electrical resistance.
To assure the correct local contact surface pressure the contact area must be carefully designed.
To my opinion you can not avoid an extensive development and testing phase. Am I correct to assume that this is for aerospace/space use? You may even have to resort to more exotic platings such as rhodium or platinum if gold against gold will not deliver.
From my experience you have to tackle the contact area pressure first.
RE: Gold Plating on Spring
My instinct does indeed say type II grade D (The hardest choice). Nad I am also leaning towards class 0 based on the IEEE paper. However as you can see I feel a little over my head on this spec, I tend not to like to spec things I am not familiar with. The contact pressure was already calculated based on the minimum required for good contact under our conditions. Basically everything has been engineered, but just wanted to make sure I was not going to lower the fatique limit of the spring based on the coating.
Thanks,
RE: Gold Plating on Spring
I am unaware of any problem that pure gold plating may cause to beryllium copper spring? The article you mentioned talks about Gold-Tin, this is a different issue. What I am aware of (from memory) is an inner metallic corrosion that may occur when soldering bare beryllium copper and melted Tin.
RE: Gold Plating on Spring
RE: Gold Plating on Spring