The authoritative public forum
  for Metal Finishing since 1989
-----

Electroless Nickel Plating Pneumatic Cylinder Bodies

I'm currently having aluminum pneumatic cylinder bodies hard and color anodized. These cylinders are used in meat packing plants. The anodize is not lasting in some instances due to the caustic wash downs. I'm not familiar with electroless nickel plating but would this be a satisfactory coating for cylinder bodies? What type would be best?

Dennis May
- Apex, North Carolina
2001

---

I have done precisely what you are discussing. It's not unexpected that the hard anodizing would be stripped off with a caustic solution. Commercial anodizers often strip existing anodized coatings with sodium hydroxide [affil links] solution.

As with all metal coatings, the key to long time performance is effective pretreatment. The aluminum should be cleaned with mildly alkaline cleaners, mild etch, deoxidized, zincated and electroless nickel. Some people utilize a sulfamate strike but I'm not sure you would get adequate throw into a narrow inside diameter on a pneumatic cylinder.

I would contact some commercial electroless nickel platers who plate aluminum. They are numerous and are in all areas of the country.

Good luck!

Daryl Spindler, CEF
decorative nickel-chrome plating - Greenbrier, Tennessee
2001

As stated, preparation is critical for your use. I would quite strongly recommend an electroless nickel strike that is designed for aluminum. Superb adhesion when done right. You might want to also consider a low phos EN. It is a lot harder than regular EN. You can not use regular temperatures for hardening the EN as it is above a copper precipitation temp of the aluminum alloy.

James Watts
- Navarre, Florida
2001