blasting process
12-26-2008, 09:34 AM,
#1
blasting process
Hi all,
I want to ask about blasting process. is it true if blasting process should be done before every spray process?

how about if the object that we want to spray has through machining process, isn't it clean already? or it is also need to be balst first before the spray process.

Thank you for the information.

Br,
Reza Bertoni
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12-26-2008, 03:51 PM,
#2
RE: blasting process
Hi Reza Bertoni

Quote:I want to ask about blasting process. is it true if blasting process should be done before every spray process?

In most cases, yes. Grit blasting (not shot or bead blasting) is the best way to prepare a surface for coating. In some cases coatings will not stick without it Sad

Quote:how about if the object that we want to spray has through machining process, isn't it clean already? or it is also need to be blast first before the spray process.

Firstly, it is most important that surfaces are very clean, but to improve bonding properties very much more grit blasting provides:

* a sharp angular rough surface texture (important for mechanical keying)
* increasing surface area (more surface to bond too)
* further surface activation by cleaning action - removing/disrupting any natural oxide films (grit blast parameters important as process can leave it own form of grit/dust contamination) making surface more likely to interact with coating with various bonding mechanisms.

There are times when grit blast preparation are not viable though. "Self-bonding" coatings like NiAl can help here, being able to stick to smooth clean surfaces of some metals, but even with this ability, "self-bonding" coating bonding is also greatly improved on grit blasted substrates. In cases where grit blasting is not available, machining/knurling a rough or threaded profile will be better than a good finish Smile
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01-01-2009, 02:10 PM,
#3
RE: blasting process
Hi Reza,

It's worth ensuring your blasting process is appropriate and your guys are doing it correctly. I've seen many expensive components damaged by people blasting them incorrectly, excessive dwelling, wrong pressure etc.
Over blasting produces a very smooth distortion which is easy to miss.... until the customer is trying to fit the part and finds a 30 thou gap!


Jim
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01-02-2009, 10:06 AM,
#4
RE: blasting process
Hi, Thx a lot for your suggestion Sir. It's really helpfull.

(01-01-2009, 02:10 PM)TurbineRepair Wrote: Hi Reza,

It's worth ensuring your blasting process is appropriate and your guys are doing it correctly. I've seen many expensive components damaged by people blasting them incorrectly, excessive dwelling, wrong pressure etc.
Over blasting produces a very smooth distortion which is easy to miss.... until the customer is trying to fit the part and finds a 30 thou gap!


Jim
Reply
01-03-2009, 09:17 AM,
#5
RE: blasting process
(01-02-2009, 10:06 AM)rezabertoni Wrote: Hi, Thx a lot for your suggestion Sir. It's really helpfull.

(01-01-2009, 02:10 PM)TurbineRepair Wrote: Hi Reza,

It's worth ensuring your blasting process is appropriate and your guys are doing it correctly. I've seen many expensive components damaged by people blasting them incorrectly, excessive dwelling, wrong pressure etc.
Over blasting produces a very smooth distortion which is easy to miss.... until the customer is trying to fit the part and finds a 30 thou gap!


Jim

Dear Mr.Reza, it is also very important to mask the componants before blasting so that compnants are not damaged
Vijay Deshpande
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