Delamination in Polyester B50TF222 top coat

[gejohn]

Hello everyone,

We are spraying Polyester top coat with Metco 450 bond coat on an inside diameter, at least 0.080" thick. We are running the metlab coupon with the part (rotating). I have the following:

1st shift: 2 operators
2nd shift: 2 operators
3rd shift: 1 operator

The problem I am having with my 3rd shifter is his metallographic is showing a delamination/separation in the first 0.005" of the Polyester top coat. This problem is only in his coating. Here are some of the theories being passed around:

1. The operator is spraying the coating on in one setting, with no cool down periods and no stops all the way until 0.080", which is causing stress on the coating.

2. He is using only one cooling air nozzle on the part, instead of two...or he is positioning the nozzle in a ineffective location.

Here is the metlab picture:[img]C:\Documents and Settings\a271tqt\Desktop[/img]

Do you think this is an application problem in the sense that the operator is hitting the "go" button and sprays to the full thickness? Or is this even a stress issue?

Thanks,

John

[Gordon]

Hi John

It does sound like your operator is doing something that he shouldn't. Does he have any incentives to try taking short cuts? I would certainly keep a close eye on him, as silicon aluminium/polyester (Metco 601) is a very tolerant coating normally (I have sprayed 601 to well in excess of 1" or 25 mm in thickness with no problems).

John, could you email your met lab picture to me and I will place it in your post above.