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


-----

Finishing process for Hydraulic Cylinder rods other than Hard Chroming

The common practice of Hard Chroming hydraulic cylinder rods is becoming a health and safety issue and may at sometime come under legislation which effects the future availability of this process. What other forms of finishing could be considered as a substitute for this process, both from a commercial and technical standpoint.

Ian Durham
Seal Manufacturer - Rugby, Warwickshire, England
2004

Chrome plating requires proper management of effluent and air emissions; it requires that we install equipment and adopt procedures to protect workrs that are different than we used 50 and more years ago. That hasn't happened to the necessary degree; and why it hasn't should really be the area of discussion.

Chrome plating does NOT pose health and safety issues if reasonably managed. Every dentist, doctor, hygienist and nurse dealing with a patient is dealing with factors that are less controllable and dangers that are far more real than hard chrome platers. But medicine has adapted better than chrome plating.

There is no across the board replacement for hard chromium plating. Electroless nickel is a possibility for some applications, titanium nitride and other PVD processes can replace chrome in other situations. Nitriding can do for some applications. DLC is expensive, but a possibility. You need to look at the exact requirements of the specific application though.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2004

---

I think what Ian may be concerned about is the proposed banning of hexavalent chromium plating within the UK and possibly the EU. The reason for this is that Cr(VI) is considered a significant health and environmental risk. However, I believe this policy is again under review because industry has finally got round to talking to the legislators and shown them that current Cr(III) technology does not supply the advantages and properties seen with Cr(VI). I believe, from a totally unofficial source, that the proposed banning may now be put on hold because there is no suitable universal substitute. This would of course be in agreement with the BATNEEC policy. Perhaps a lesson has been learnt here; when legislators decide to introduce restrictions on things, they should talk to the end-users before imposing their policies. Similarly, the end-users must work collectively to show the legislators that what they are doing is inpracticable and not just belly-ache about the law makers not understanding what is going on in the real world. Neither side wants to be in conflict with the other - it is just a matter of talking!

Getting back to Ian's original request - one possible substitute may be tin-nickel, but it all depends what the end use conditions are. Try asking the Tin Council (ex- ITRI) in St Albans.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2004

--
Ed. note: You may want to hear "The Lost Art of Tin-Nickel Plating".

HVOF (high velocity oxy fuel) spray with tungsten carbide or chrome carbide powders is a widely used replacement for plated chromium. The ASM International has a sub group devoted to thermal spray, and lots of information can be found in the proceedings form this source.

Joe Kubinski
- Woonsocket, RI, USA
2004