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Mirror finish hard coating for machined aluminum

I was wondering if there are any means of getting a mirror finish, hard (RC>60) coating on a machined Al356 casting? Also would such a method be relatively expensive?

Nishant Nair
Manufacturing Engineer - Rochester, New York
2007

Yes and yes, Nishant. Between electroless nickel, hard chrome, and decorative nickel-chrome I think you can get there -- the exact process probably depending on how mirror is mirror.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

Being a casting, porosity may be an issue with your part. In such case, you may have to include an acid copper underplate after the right steps to prepare the surface for it, and perhaps also an intermediate polishing or grinding. Acid copper baths are well known for their ability to fill-in or bridge over pores and defects and give a continuous surface which is necesary for a decent mirror finish. Finnaly, hard chrome meets your desired 60Rc+ hardness without the need of a post heat treatment.
G. Marrufo-Mexico

Guillermo Marrufo
- Monterrey, Mexico
2007

Just a reminder. Mirror finish is a relative term. Your surface finish will only reflect what you are starting with. Meaning, if you are starting with a rough surface you will get a rough reflective finish. A smooth, reflective finish is different from a mirror finish.

AF Kenton
retired business owner - Hatboro, Pennsylvania
2007

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