I need your help again please.
We are talking about solid content in enamel copper wire.

1) What is the difference between different kinds of varnishes with different solid content but the same characteristics?
2) Do I have to change the oven settings, in which way? And the speed?
3) Regarding primer coat, what I have to do?. This varnish increases adherence properties but does it also give other properties or issues?
4) And the top coat?

If you need more explanation just let me know.
Thanks in advance for your help.

Nicola

Not all enamels/varnishes are alike. Sometime they even vary from batch to batch.

I assume when you say "the same characteristics" you mean that the varnishes make a finished product with the same thermal rating. Just because the finished products are rated the same, it doesn't mean that the processes to make the finished product have to be the same.

It is not unusual to have to have different oven settings for different varnishes. Again you might have to even make minor changes with the same varnish if from different batches.

I don't think you really mean primer coat the way it sounds like you do. when painting a car or a machine it is not unusual to put on a primer coat. The finish coat is then put on over the primer coat.

When making wire people will say "the base coat" or the primary coat but is not a primer to make the top coat adhere better. There are many different thermal ratings of varnishes and finished wire products. A lower or intermediate varnish may have just the primary coat - urethane or modified polyester for example. It may be over-coated with nylon or a bondable material. A higher thermal rated varnish polyester or polyesterimide may have a nylon or bondable overcoat or even an amide imide overcoat.

I don;t remember all of the different varnishes without looking at a reference book but there is no one varnish that meets all needs and no one oven setting that works with every different varnish. To maximize the capabilities of the oven system, you need to set, tune or fine tune the oven for each varnish you use.

Thanks Mr. Richard for your help and support,

I just want to ask you something more.
Regarding Base Coat, Middle Coat and Top Coat, do we have the same behavior in the oven (PE, PEI, PAI, PU and so on)?
Or is evaporation and/ or curing different?

Thanks again

Nicola

I thought I had replied to this but don't see my response so I'll try again. Do the base, middle or top coat above have the same behavior in the oven. No. Oven manufacturers will ofter quote you speeds for a single enamel coating. It can be what some people call single build or heavy but they seldom quote speeds for wire with multiple types of coating. There are way too many combinations for them to provide info for all.

Since each enamel has different characteristics you have to adjust the oven so that the finished product passes all of the required tests and you are able to produce it at a speed that gives you the best quality and efficiency. You can almost figure that if a machine can run quality single build wire at a speed of X then increasing to heavy build will slow it down 10-20%. If you put an overcoat on single build then it will probably slow you down 5-15%. Since you are running slower you have to adjust the oven by changing temperature, air flow, fan speed, or a combination of oven settings.

Evaporation and curing is different for different enamels so you have to adjust the oven setting and or wire speeds so that you can produce the best quality at the highest possible speeds.