Topic: Help in Vibratory Polishing of Bearing Steel

Hi Guys,

This is my first post to this forum and hence please bear with me if I have broken some rules

I am from India and we manufacture some components from bearing steel. After machining they are heat treated and as a result their hardness is around HRC 62-65.

Later the components are polished in Vibratory & Centrifugal Polishing Machines. Abrasive ceramic media (Grey) is used for deburring and polishing while for very silky finish we use non abrasive type ceramic media (white).

Initially we put the components in vibratory machine filled with abrasive ceramic media and mild solution of oxalic acid to clean the oil and salts of heat treatment. After 30 mins we wash out oxalic acid and then mild solution of caustic soda is added and the machine runs for another 90 mins. Then we again wash out the solution and add another shot of caustic soda and run the machine for 90 mins.

After this the components are put into centrifugal polishing machine where we use non abrasive type media and a mildly thick greenish liquid to get very silky finish. The machine is run for about 1 hour.

Now the problem:

Though the finish we receive is pretty good and acceptable the luster is dull and hence we need to manually buff the rings as hard chrome coating is the next process. I have noted that many companies in India as well as world over produce same components with better finish without buffing their components.

Where do I need to make alterations?

Please help.

Thanks for reading the long post.



Re: Help in Vibratory Polishing of Bearing Steel

The matte finish you are describing is very common with mass finishing.  There are several ways you can try to improve the luster of your parts without manual buffing:

1. Use a higher grit (or non-abrasive) compound in your final finishing cycle.  Any abrasive at all will leave fine scratches.  The finer the grit of the abrasive, the smaller the scratches will be.  I'm not sure what is in your mildly thick green liquid, but see if you can use a liquid with a finer abrasive.  You may want to use something less viscous to help rinse away any residual metal fines and debris, which should help improve your finish.

2. Depending upon the material, you may also want to look at chemical polishing or electro-polishing.  This works very well to remove the light matte finish you are describing.

-Dustin Gebhardt, CEF

Advanced Manufacturing/Finishing Engineer


Sanford, NC