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 Post subject: Re: Zinc Plating Kit
PostPosted: Tue May 21, 2019 2:19 pm 
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Joined: Fri Mar 19, 2004 6:19 pm
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Location: near Baulkham Hills, NSW
winabbey wrote:
simonw wrote:
Hey Timmy ,
Was thinking about that too. I think lapping them in setup should make it all good.
Zinc has 1/3 toughness of steel , so yes it will wear quicker.

Good spot though

That's why I would resist plating items like ball pins and sockets, and other parts with a load bearing surface. I guess it's a personal decision.


I bought some grade 8, 3/8 UNF hex bolts once to fit the Mini ring gear to a Quaife diff. These were zinc plated. When I got to 45 lb/ft torque the threads all peeled off. They are supposed to be torqued to 55 lb/ft.
So now I don't trust using plated bolts for high torque applications..
I went back to the fastener shop and bought some grade 8 black ones, they torqued up with no problem.

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 Post subject: Re: Zinc Plating Kit
PostPosted: Tue May 21, 2019 9:02 pm 
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848cc
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Joined: Sun Oct 13, 2013 5:28 pm
Posts: 56
Location: Hobart, TAS
Generally, in engineering, plated bolts up to and including Gr.5 (or metric 8.8 ) are OK if from a reputable source. I avoid any plating on fasteners above those grades due to the hydrogen embrittlement issue.

My understand is that plating of bolts above Gr. 5 can be successfully achieved if the process is controlled properly but I've never been confident to go there.

Bolted joints are a minefield!


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 Post subject: Re: Zinc Plating Kit
PostPosted: Tue May 28, 2019 2:07 pm 
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848cc
848cc

Joined: Fri Oct 06, 2017 6:39 pm
Posts: 79
Location: Perth, WA
Reminds me of a time when we torqued up M36 grade 10.9 bolts to 2500Nm. The bolts came with a plating and the result was the threads stripped like cheese...

Here are the photos:


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