Posted by Alex (192.35.25.6) on 01:38:13 31/03/06
In Reply to: Re: T800 Coating Thickness limit by HVOF posted by Alexei Goncharov
Thanks for all the recommendation.
To update, I have tried some preventive action and seems the
lifting or delamination has been improved significantly.
1. As recommended by Gordon, I have put part temperature monitoring
into place, making sure that the part temp. would not exceed 120oC
at all time. stop-spray method,for sufficient part cooling-off
period.
2. I make sure the preheating is done with the preheating temp. of
120oC~~130oC. Would it be ok? too much or higher
better?
3. I have changed corrodum grit size from 60 to 46, creating a much
rougher surface. and make sure all best practises observed after
grit blasting. And make sure all edges are blasting effectivel with
Ra above 150 uin.
4. Use M.E.K to wipe the part if any touching is done to remove
contamination.
5. I have also chamfered the edges to about 30o. As the edges of
flange thickness is limited, so, it's hard for me to have a 45o
chamfering. What would be the best undercutting or chamfering angle
in this case?
6. Also, I practise clearing of overhang coating at each
stop(cooling) to allow exccesice ooverhang coating
build-up.
These area some practice I would like to share to have put a stop
to the lifting problem.
The next problem I have is the edges chippings during benching of
the overhang coating. I m still trying to solving this problem like
reviewing the benching methods and so on. Any opinion and advice on
this area?
Thanks for all the advice.
Regards,
Alex Chan
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