Surface finish improvement in barrel tumbling process

Sirs,

We are manufacturing bearing components by barrel tumbling process.

Existing process:

Input Surface roughness Ra - 0.20 to 0.30 microns

2 Deburring cycles with High abrasive cylinder ceramic + HD balls & Deburring powder - 45 mins/cycle
3 Polishing cycles with Low abrasive cylinder ceramic + HD balls & polishing liquid - 45 mins / cycle

After the above process cycles we are able to achieve surface roughness Ra - 0.10 to 0.15 microns.

Currently we are achieving Input Surface roughness Ra - 0.07 to 0.10 microns. I have tried out the above tumbling process for the current improved input Ra.
But output Ra increased to 0.15 microns.

Kindly advise me what I can do to achieve the output surface finish Ra < 0.05 microns.

Thanks & regards

A couple of basics. The size of the abrasive in the media will effect the final finish. The smaller the size grit, the finer the finish. When achieving very fine finishes, you do not want any abrasive at all. Use porcelain media if you are doing a wet process. For the smoothest surface finishes, I prefer to use dry organic abrasive media followed by a a treated polishing organic media.