Metal finishing Q&As since 1989

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CHROMIUM PLATING ON RINGS

We are using a ring made out of En 31 hardened on which a very light piece touches and rotates. Limitation of speed of rotation of the piece over the ring by sliding exist and initial running time to be given to reduce surface finish. We want to increase the speed of the rotation of the running piece by reduction of surface friction. We have tried chromium plating on this ring. The performance is better. We like to know that during the running whether the surface will peel-off by adhesion and slight impact created by moving traveller. We are using chromium batch with catalyst supplied by trade name. Is there the possibility of improving the process further ?

We applied hard chrome plating on the surface of the ring to about 40 microns. The performance appears to be better and in the short time we are carrying out the trials.

NARASIMHAN P.L.
- COIMBATORE / Tamil Nadu / India
2000

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Dear Mr PL Narasimhan,

When plating En 31, you have to think about Hydrogen Embrittlement. This will lead to peel off and snapping of your thread. Why not try Electroless Nickel ?

This will not cause any embrittlement and chances for peel off are much less. Hard Chrome is preferably used in hydraulic applications where the oil retention properties are required, not so much in textile applications such as yours, particularly with such high hardness steels.

Send me a few parts if you like which I can EN plate and give you for evaluation if LMW does not have EN facilities. Regards,

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

2000

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Hi!

Mr. Narshimian,

after Electroless nickel plating of around 25-30 microns I suggest you hard chrome plate the rings this will eliminate the galling effect yes you can also Hard chrome plate the ring up to 50- microns and then subject it to oven baking at 180-200 °C for 2 hours.

MAHENDRA
- Belgaum India
2000