Problems with Oxidized Zinc components

[tomtom]

Hi all,


I am experiencing a problem right now, A batch of Zinc components is oxidized with clear visible white spots everywhere before it has the chance to be satin plated. Is a proper way to deal with the oxidized surface? can I still save this batch of Zinc components and send it off for plating? If the components can be re-treated correctly and be plated, will the oxidized surface from the inside of the components cause a problem in the future? Please help!!

IMG_20130418_160051.jpgIMG_20130418_160435.jpgIMG_20130418_160452.jpg

[PinkertonD]

You need to look upstream of this position and find out why they are "oxidized." Were they rinsed in something? What was the machine cutting fluid? You need to understand the chemical reaction that produced the "oxidizing," It may not be an oxide at all, but another compound formed out of an adverse reaction with something in the process up to this point.

Until you understand what you have, you cannot form a competent method of correction if it is at all possible. The "oxidizing" needs to be looked at by a Metallurgist to determine if there is pitting, how deep and what ramifications are there as a result.

Just looking at the parts and asking on a forum will do no practical good for what looks like some expensively machined or die-cast parts. You need professional technical help here!

At a guess and not knowing the cause, I would suggest scrapping the lot and starting again. Especially so if these parts are for a customer you would like to keep for future orders. Think of the big picture.

[tomtom]

Thanks PinkertonD,

I do suspect the quality of raw material used as I am currently finding out the composition from our material supplier. but in the mean time. i am hoping to rule out other factors that may or may not be the cause this. your suggestions help a lot.

Assuming the quality of raw material is not the issue, I still need to find the caused of these surface defects. I was told from Several different platers that these white spots are definitely Oxidization, to what have caused it is still a mystery.

My knowledge, Zinc should not oxidized so easily especially when they are only fresh out of the injections.

You need to look upstream of this position and find out why they are "oxidized." Were they rinsed in something? What was the machine cutting fluid? You need to understand the chemical reaction that produced the "oxidizing," It may not be an oxide at all, but another compound formed out of an adverse reaction with something in the process up to this point.

Until you understand what you have, you cannot form a competent method of correction if it is at all possible. The "oxidizing" needs to be looked at by a Metallurgist to determine if there is pitting, how deep and what ramifications are there as a result.

Just looking at the parts and asking on a forum will do no practical good for what looks like some expensively machined or die-cast parts. You need professional technical help here!

At a guess and not knowing the cause, I would suggest scrapping the lot and starting again. Especially so if these parts are for a customer you would like to keep for future orders. Think of the big picture.

[PinkertonD]

Tom2, it does not matter what anyone, platers or otherwise tells you, until a Metallurgist has assessed what you have it is all a guess and that counts for squat.

If you did not clearly define the required metal composition in the Purchase Order then there is little to fall back on no matter what the supplier gets back to you with regarding composition. If you did define it then it is up to the supplier to show they have conformed, but to force that you will need professional Metallurgical assistance.