Where the
world gathers for metal finishing
Q&As since 1989


-----

Need 22 micron thick zinc plating on fasteners

Hi,
I am writing from Mumbai (India). We use a good quantity of white zinc plated fasteners of smaller sizes like 6x20 mm, 8x25 mm & 10x35 mm. The average micron coating available here is 6 to 8 micron.

We are currently servicing an order for a nuclear power plant where the requirement is of 22 microns. We are finding it difficult to find suppliers of zinc plated fasteners with 22 micron zinc coating.

My question is whether such fasteners are available in zinc plated or do we have to go for stainless fasteners (will be too expensive)? Hot dip galvanizing might not be possible due to small sizes.

Awaiting your valuable reply.

Aditya Vutha
Steel fabricator - Mumbai, Maharashtra, India
May 14, 2011

---

May 18, 2011

Hi, Aditya.

I have seen production barrel zinc plating of up to about 0.006" to 0.007" thick. My recollection was that it took about 75 minutes of plating time (although it was a while ago and I could be off by a bit). 22 microns would be thicker by yet another third. I have never seen fastener plating that thick. I think, but do not know, that it is achievable. I assume that there would be a lot of rejects, that plating for 2 hours would be costly, and that 100% inspection might be required. You also need to determine whether the threads on small fasteners would be to distorted by this.

But this is a guess and hopefully someone will stop by who has either done it or given up on the quest :-)

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

---

May 21, 2011

Hi,

I guess you can go for zinc coating by dipspin method or hot dip galvanizing, where the rejection level would be not so high.

Praveen Kumar
plating process supplier
Mumbai, India

---

It is possible but not - off the shelf as universally thickness of Zinc plating is 8-12 microns.
You will have to develop a vendor for you to plate your spec.
Regards

T.K. Mohan
plating process supplier - Mumbai, India
June 14, 2011

---

July 27, 2011

Hi,

We do a 20-25 µm zinc plating in a cyanide bath. On a M10 product it takes about 3 hours of plating.
We have never experienced any problems.

Gary

Gary Joseph
Johannesburg,
South Africa

---

August 6, 2011

Ted, I think we should advice the scientists of nuclear to learn more about Zinc plating and its characteristics. Asking a vendor to plate 22 micron on a fastener is madness!! What will be the fate of the threads! Will it pass go-no go test? It is not the question whether we can plate and get 22 microns but why you need 22 microns for the fasteners.
Maybe these guys have been earlier doing nickel plating and trying to impose this spec on Zinc.
Regards
Mohan

T.K. Mohan
plating process supplier - Mumbai, India

---

I think that's a valid point, Mohan. It would be foolish to be applying all that thickness, and wasting all those resources, if it was to no valid purpose. But I don't know enough about it to know whether it serves a valid purpose or not.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
August 6, 2011

---

August 11, 2011

My company would be happy to plate these fasteners for you.
Please get in touch if your requirement still exists.

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India