Smooth powder not sticking to DIe cast

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Raiderrob74
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Smooth powder not sticking to DIe cast

Post by Raiderrob74 » Tue Jun 12, 2018 8:35 am

Would anyone know why we would be having problems with a smooth powder sticking to Die cast aluminum parts? These got through a 6 stage washer system with our stage 3 being iron phosphate then three more rinse cycles. When we use a textured powder we do not have the adhesion problems.

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Jay V
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Re: Smooth powder not sticking to DIe cast

Post by Jay V » Tue Jun 12, 2018 9:18 am

I would expect adhesion problems if the surface is smooth and has a gloss to it. If so, you need some type of etching or blasting to create profile or at least dull the surface.

Are you certain you have a full cure on the parts? Have you checked for anything on the surface by wiping a part with a white rag before it gets coated?

Just some other things to check, but I never coat over a glossy surface unless it's absolutely necessary.

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duke46
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Re: Smooth powder not sticking to DIe cast

Post by duke46 » Tue Jun 12, 2018 10:02 am

I have coated over chrome and polished aluminum for years when using candies and never had any problems or complaints latter.

Now are you having problems when shooting it and it not sticking? If so that would be in the grounding of it and your ground would need to be better.

Or after you have coated and curried it then it wants to come off to easy and if that is the case then it is not fully curried and is wonder you have not had problems even with using a texture?

J is correct that media blasting/sanding or a good etching helps a lot with powder getting a good bit on the item. Some companies only use some sort of chemical for etching but that is used mainly in production plants where they are turning out lots of parts a day. I have seen powder fail because of that but most of the time it will outlast the warranty and that is bad for the consumer for sure.

Hope you figure it out but that is about all I can think of at this time. :?:
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Raiderrob74
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Re: Smooth powder not sticking to DIe cast

Post by Raiderrob74 » Tue Jun 12, 2018 11:56 am

duke46 wrote:
Tue Jun 12, 2018 10:02 am
I have coated over chrome and polished aluminum for years when using candies and never had any problems or complaints latter.

Now are you having problems when shooting it and it not sticking? If so that would be in the grounding of it and your ground would need to be better.

Or after you have coated and curried it then it wants to come off to easy and if that is the case then it is not fully curried and is wonder you have not had problems even with using a texture?

J is correct that media blasting/sanding or a good etching helps a lot with powder getting a good bit on the item. Some companies only use some sort of chemical for etching but that is used mainly in production plants where they are turning out lots of parts a day. I have seen powder fail because of that but most of the time it will outlast the warranty and that is bad for the consumer for sure.

Hope you figure it out but that is about all I can think of at this time. :?:

Duke Thanks for the reply back on issues. Our issues in when it is sprayed and goes thru our cure oven at a temp of 400 for 10 mins when we go to do our cross hatch test this powder will flake off. These have been blasted and other ones of the pieces go thru a tumbler. If we were to spray these with our text poder this will adhere & then we have to run this back thru to powder smooth over the top of it.

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Jay V
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Re: Smooth powder not sticking to DIe cast

Post by Jay V » Tue Jun 12, 2018 12:54 pm

Raiderrob74 wrote:
Tue Jun 12, 2018 11:56 am
Duke Thanks for the reply back on issues. Our issues in when it is sprayed and goes thru our cure oven at a temp of 400 for 10 mins when we go to do our cross hatch test this powder will flake off. These have been blasted and other ones of the pieces go thru a tumbler. If we were to spray these with our text poder this will adhere & then we have to run this back thru to powder smooth over the top of it.
Ya, not duke, but 400 for 10 min is the cure time, not the total time spent in the oven.

Slow down the oven.

Raiderrob74
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Re: Smooth powder not sticking to DIe cast

Post by Raiderrob74 » Fri Jun 15, 2018 5:56 am

Ok update on our problem. We are getting our cure time of 400 deg for 10 min like the PC company recommends. These have been sandblasted/etched from the vendor & we are still getting the issues with any of our smooth colors not adhering to the Die cast parts. The powder will stick fine to the sand cast parts. Still get the same scenario to where our texture powders will adhere to the parts with no issues.

Kind of lost at what to do now, Any thoughts?

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Jay V
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Re: Smooth powder not sticking to DIe cast

Post by Jay V » Fri Jun 15, 2018 10:00 am

Raiderrob74 wrote:
Fri Jun 15, 2018 5:56 am
Ok update on our problem. We are getting our cure time of 400 deg for 10 min like the PC company recommends. These have been sandblasted/etched from the vendor & we are still getting the issues with any of our smooth colors not adhering to the Die cast parts. The powder will stick fine to the sand cast parts. Still get the same scenario to where our texture powders will adhere to the parts with no issues.

Kind of lost at what to do now, Any thoughts?
I guess I would look at the possibility of some type of surface contamination on the die cast parts (like some type of release) that's not being removed by the wash system.

There are a few contradictory issues going on, like the powder acting fine on sand cast parts but not die cast parts and texture powder not presenting any problems at all - so it's complicated...

Are the die cast parts similar in size to the sand cast parts? How are you checking that you have adequate cure time and temp?

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Jay V
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Re: Smooth powder not sticking to DIe cast

Post by Jay V » Tue Jun 19, 2018 9:13 am

Resolved the problem - or gave up?

Raiderrob74
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Re: Smooth powder not sticking to DIe cast

Post by Raiderrob74 » Tue Jun 19, 2018 10:28 am

We are still trying different avenues. We have took on of the problem Diecast and ran it thru the washer for the phosphate to etch this than we have sandblasted this here and ran back thru the line & are still having the adhesion issues.

We are sure we are getting the cure time have ran multiple heat data packs on the parts and they are seeing there cure time.

Checked this when it cam out of the washer with a white rag and dont appear to be getting any residual that is wiping off of the parts.

So as of right now not to sure on what else to try.

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Jay V
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Re: Smooth powder not sticking to DIe cast

Post by Jay V » Tue Jun 19, 2018 12:31 pm

Are there any visible defects on the parts?

Try a different, but similar, powder? Different wash chemistry?

Getting adhesion problems on a blasted surface is unusual in itself.

Can you post any photos of what you are dealing with? Size/weight?

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