A double helical gear set was sent out for clean up after setting in storage for a long time. I know typically that when gears are new they have a polished appearance like fresh cut machined metal. The gear set that came back had a gray metal look. Appears to have been cleaned by corn cob blast or other media that would not polish the metal. What is your experience with this condition. If the gear set is installed correctly will a problem show up from being cleaned in this manner?

Are any requirement in the process where the gear will be used, about the cleaning level that the parts must have?

If not polished (like fresh cut metal), did you expect the gear will release more metal debris or dust than before?

I have some concerns.
1. What effect will this have on tooth wear pattern.
2. With this kind of finish (blast finish) will the blast areas where teeth mesh have a wear problem. Have higher gear mesh vibration than with machined surface in a short time.

Just not sure what to expect. Wonder if this would be a good, better or best practice?

I wouldn't grit blast the gear polishing the metal. Just like a wound, if you keep peeling of the skin, it only get worse.
I recall the few time we replaced some gears that we washed away the old grease, and with sandpaper cleaned the bearing seats, oil the whole thing and put to work again.

Update. Gear that was sent out for cleaning was very rusty. Allot of pitting was found and the clean up may not have been from the blast but from the rust pitting. A representative of a gear manufacturer and repair center will be on site today to give recommendations. Currently the gear that was being considered for change out will stay in place. I have requested the gear representative also give recommendations for a best practice to correct this gear damage. Gear had been storage improperly for about 25 years. Current owner of company has only been in place for 6 years.

Climate control was not done. Have recommended a review of storage practices for all rotating equipment.

Is it possible to repair the gear by weld overlay the pitted spots and remachine to its original smonthness or buy a new one?

Which AGMA spec applies to repair of gears?

Gear that they cleaned up was inspected by a gear house representative yesterday. It was sent back to shop for further clean up. I will be following this for the results.

Not sure about any spec's but will be asking for detail.

Shouldnt one thought to consider is what if any type of heat treating this gear has?

What is the Rockwell "C" hardness value on this gear ?

If the gear is hardened thru induction heat treatment its doubtful the blasting would cause the teeth to eat away.

If the gear has no heat treatment at all, and way low on the Rockwell "C" scale then I could see where the blasting could irregularities in the teeth profile.

The gear representative said that the cleaned up gear was a better gear than the current. Part of that was base on how the gear was made. Do not have the detail on that part of the conversation yet. The decision has been made to get the unit back in service and then take the next step to decide if we replace or repair the gearbox.