cleaning gears and bearings after dye penetrant inspection

[Tmoose]

Are Spot Check developer and penetrant abrasive or otherwise harmful to carburized gears and roller bearings?
In place inspection of gears in gearboxes is desired, and cleaning will be incomplete.

thanks

Dan T

 

[CoryPad]

It depends on a few things, but in general, those products are not harmful to gears and bearings.

 

[metengr]

What kind of gear box?

 

[Metaljon]

I would be very suspect about performing inspections of gearboxes in situ using dye penetrant or developer. How are you going to remove all traces of oil for a start? To do such a job properly requires that the gearbox is dismantled. Even if you could do this in situ you risk major contamination of the lubrication system or at worse some type of lubrication reaction with potentially very serious consequences.

 

[Duwe6]

Need for adequate cleaning -- agree absolutely
Oil contamination, not so much. The cleaner, and the 'vehicle' in the developer is a middle-cut of naptha [Zippo lighter fluid], and the quantity used and not removed by wiping during the PT process is waaaay less than an ounce. Plus, the solvent flashes [evaporates] at room temp. Never seen a gearbox that runs cold to the touch.

The developer is chalk, ground to face-powder consistency and suspended in solvent [naptha]. Unremoved developer powder might act like 'jewelers rouge', but I suspect not. It is just too soft to 'lap' your steel gears. And essentially all of this white powder is easily removed with proper PT post-cleaning

The penetrant is a light oil with mysterious additives. If the PT tech applies the dye with a small brush, ALL the dye that has not wicked into cracks and pores must be removed during the PT process to allow the developer to show [only] surface-breaking defects. Nature of the PT process.

Thus the liklihood of contamination is minute-to-nil, if the PT is done to ASME/ASTM spec's. 'Spray & Pray' by an uncaring mechanic is a different story. Penetrant getting into your lube oil is a probabil;ity in that case.

 

[gtaw]

There is a serious problem with testing a gear box that has not been disassembled and properly cleaned before testing. Penetrant testing is suitable for detecting discontinuities that are open to the surface. Any materials trapped within the discontinuity are going to prevent the penetrant from being pulled into the open discontinuity by capillary action. The reason, simple, the discontinuity is already filled with condensation, oil, grease, or other contaminents that will prevent the penetrant from entering the discontinuity.

Proper cleaning entails removing all surface contaminants that will prevent the penetrant from wetting the test piece surface and any contaminants that are in the discontinuity that you want to detect. Precleaning the part in preparation for testing is typically the most expensive time consuming part of the penetrant test. Improper cleaning is often the reason the penetrant test fails to locate discontinuities of interest.


Best regards - Al