52CNS top coat

[Laurent]

Hello,
Bond coat 450NS
Top coat 52CNS
Operation: Diameter refurbishment to nominal.
Base is aluminium
Part is a bearing support, therefore subject to oily environment.

Our process includes degreasing, masking, sand blasting and spray.
Unfortunately last 3 parts showed a bonding problem while machining.

52CNS isn't easy to process, but is there any precaution we should take to prevent it?

Thanks for your help and/or ideas.
Cheers

[Laurent]

Hi,
We finally decided to increase base machining diameter of 0,1mm.
Left 0,12mm of bond coat, then use the remaining 0,18mm to spray 52CNS.
We machined at nominal.
We added a chamfer at the top to prevent grip during assembly.
It seems ok, although plasma sample to confirm abrasion and bonding.

Conclusion:
- machine at max tolerance the base
- spray a mini of 450NS
- spray a maxi of 52CNS (to allow enough thickness at final machining)

Thanks