Any alternatives to hard chrome plating for machinery driveshafts
We need either assistance or at least some guidance. We are a metal finishing machinery manufacturer. From time to time, we need to have machinery driveshafts chrome plated. This is done primarily for abrasion resistance purposed. Once chromed, the shaft is ground for smoothness (one surface contacts a rubber grease seal, so it must be very smooth). The process produces a reliable driveshaft component. The problem is that it has been difficult to find good chrome plating service and once found, it is (or soon becomes) very expensive. Quantity is around 25 shafts/year, each one being about 10-12" long with approximately a 2" O.D. shaft connected to a 6-10" flange.
The question is this - for our application, is chrome plating really the best approach? If so, great - we'll just have to keep finding ways to reduce costs. If not, what else should we consider?Dan Regan
mechanical prep specialist. - Cinnaminson, NJ
You might want to consider some of the PVD hard coating options.
Society of Vacuum Coaters
Albuquerque, New Mexico
Mr. Mattox is
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Dan: While you might want to look for a substitute on the environmental basis of trying to minimize chrome plating when possible, I very strongly doubt that you will find PVD less expensive. And as long as you already have found chrome plating to be highly suitable for this function, I don't think you'll find anything that functions as well (or better). When it comes to machinery with lubricated rubber seals, it's not solely a question of smoothness, but also of coefficient of friction, and of oil-retention properties--and chrome plating excels at all of these.
Ted Mooney, P.E.
Pine Beach, New Jersey
Electroless nickel has many of the same properties that you are looking for and probably would be cheaper in the ones and twos quantities. Another plus is you would only have to pre grind, post grind would not be required. Drawback is thickness. The practical maximum thickness for EN is 0.0015". This probably will not have the length of service that the chrome will.
Also, you can regrind and rechrome the shaft a great number of times.
What probably is killing you is the minimum lot charge. You could very probably have two or possible even three shafts done for the price of one. This would mean that you would have to keep inventory longer than you might like because of several size shafts used.
Your shaft is about the easiest size and shape that there is to chrome plate if your plater is using conforming electrodes. A good plater, after a learning curve of a few parts, could cut your "for grind" thickness to one or two thousandths which would save you several dollars per part on the grinding operation.
If you had parts on the shelf, you could find an excellent plater and afford to ship anywhere in the USA, in lots of say 5, and have significantly cheaper per part plate and grind cost. My nickel says that you would have higher quality product also.James Watts
- Navarre, Florida
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