Plasma pit problem

[Maximusss2689]

Hi everyone,

This is my first post but I have been following this forum for a long time and I always found helpful topics.
Thanks to everyone for this. 

I need your help about one issue that's why I'm writing. Recently we have a pit problem on the plasma coating that we see after grinding operation.
We use F4MB-XL gun and 81vfns powder. We don't see it on all the parts but it occurs sometimes. What can be the reason for this? I also added some photos for the pits that we encounter. We have some doubts about the gun spare parts but even we changed the newly we still see after changing.

[Lemster68]

Your photos are not showing. It is likely that the fine powders are accumulating on the injector before they get blown off as a clump. Try to eliminate moisture as part of the problem by adequately drying the powder in a heated cabinet, with the lid loosened or otherwise ventilated.

[Maximusss2689]

Your photos are not showing.  It is likely that the fine powders are accumulating on the injector before they get blown off as a clump.  Try to eliminate moisture as part of the problem by adequately drying the powder in a heated cabinet, with the lid loosened or otherwise ventilated.

Thank you for your response. I will take care and investigate. Normally powders are waiting in the furnace but after production it stays on the feeder. that can be problem. There is problem about photos. I tried to upload again but it seems it won't work again. In case of not uploading issue I add their link. Now can you see? 

https://ibb.co/XF6ZYwm

https://ibb.co/4RR3F43

[Lemster68]

Yes, I can see the photos now. It is hard to tell the scale, but it seems that they are quite small.