E-coat on Galvanized Steel parts - Visible and irregular texture on the surfaces

[roland_lu]

We are in stamping and welding business in automotive industry. Currently we have experienced some problems with the galvanized steel parts after e-coating. There are some visible and irregular texture on the surfaces and we got complaints from our customers . When we tried to talk with our E-coat vendor to find out the root causes, they insisted that it is the plating problem. Do any of you have the expeirence and knowledge that could shed some light on this issue?

[Marc]

Did your e-coat supplier visit your facility? Or just talk to you and maybe evaluate some parts you sent them?

Is it a visual issue as opposed to a 'texture' you can feel?

[roland_lu]

Both visible and finger-feelable, though the parts do not have appearance requirements, just for anti-corrision, sometime i feel it is not right and necessary to e-coat after galvanizing

[Marc]

Any e-coat experts here? I've been through some e-coat issues but it's not my forte.

As to whether it is 'right' or not, have you done any durability or reliability testing (such as salt spray) to determine whether it is important or not?

[roland_lu]

Originally Posted by Marc

Any e-coat experts here? I've been through some e-coat issues but it's not my forte.

As to whether it is 'right' or not, have you done any durability or reliability testing (such as salt spray) to determine whether it is important or not?

We do not have the equipment and capability to conduct salt spray test. We have to trust the vendor's test report, and the results are good ? !

[Marc]

I keep coming back to the appearance issue. I have seen the streaking problem. I just wasn't involved in the solution. I know we had the e-coat supplier and the equipment manufacturer in (in this case there wasn't a clear visual requirement, either, but the customer complained) and between them and the manager who over saw e-coat they solved the issue. I know they did some disassembly of parts of the line, cleaned it up, but that's about all I remember.

[Miner]

Originally Posted by roland_lu

We are in stamping and welding business in automotive industry. Currently we have experienced some problems with the galvanized steel parts after e-coating. There are some visible and irregular texture on the surfaces and we got complaints from our customers . When we tried to talk with our E-coat vendor to find out the root causes, they insisted that it is the plating problem. Do any of you have the expeirence and knowledge that could shed some light on this issue?

I have a little experience with e-coat, but am not an expert. My experience has been that appearance issues where typically (but not always) caused by either the condition of the underlying substrate or the thickness of the coating.

[dbulak]

What type of coating is being applied? Don't forget that there are standards for the coating thicknesses. It also depends on how the material ordered was coated. Over the last 35 years I have seen alot of electro plated galvanized. Alot has to do with what type of coating is applied. The typical coating is zinc and when applied is very smooth. Don't forget they are applying a very small amount to each side and if done properly leaves the surface smooth. If there is an irregular texture then go back to the coater. They will know what happened. Don' forget, they have to apply coatings to standards- ASTM.