Etching of Carbon Steel Plate

First question anyone should ask, so I will , is: did you measure the thickness in that area prior to the process, with several measurements in the exact locations of non-uniformity? Because, it could have been manufactured that way...

we assume that the plate was uniform everywhere so we didnt check it prior the process

What do you advise me to do??

First question I'd ask is what's the process? How well is it rinsed during etching?

How clean was it proir to etching?

So you now have 3 possible reasons, 1) wasn't cleaned enough prior to etching and, asuming chemical, one area reacted differently, 2) wasn't cleaned enough after and the other area continued to etch, and 3) it was manufactured that way.

What to do now? I have been out of the biz for awhile but when I was, I was not aware of any method to correct the problem, not to say there isn't one out there.

Agreed.

Depending on the surrounding topography, and the cost of the plate, maybe surface grinding. If they're really desperate, maybe a mill.

is there any appropriate proportion for the etching solution that i can get an optimum results for the carbon steel plate after the etching process?

Well, we haven't been told what you are using for the etchant.

However as i indicated earlier having a suitable means of agitating the solutions in process to prevent stagnation and depletion of the reacting chemicals is important.

Obviously so is temperature control and proper mixing of the solutions.

Cleaning of the plates before etching is also key to getting a uniform etch.

Milo

we are using ferric chloride at 40% plus an addition of 26 liters of water as the etchant

Specific gravity of ferric chloride should be 42degrees baume. 130 degrees Fahrenheit is typical, and with proper agitation should etch out at about 0.001" per minute.

It also occurs to me that perhaps a small irregular layer of maskant or other fluid might have originally overlain the area that did not etch, retarding the reaction.

Milo

thanks for your reply and what action can be taken to prevent the creation of this irregular layer??

if the irregular layer occur...what action should i take??Thks

We believe that we have provided an abundance of information to help you determine what is going on in your process. A close look at the irregular patterns and contours visible on your picture make agitation, and stagnation of etchant most likely processes to investigate. Especially if you convert the mm per minute of etch to thousandths of an inch to compare to the facts I gave you about removal per minute above.

If the irregular layer occur what action should you take? Scrap the parts from that batch.

The real question is How can I prevent irregular ething from occuring in my process:

1) make sure plates to be etched are fully clean and no residual maskant or oils remain;

2)Test specific gravity of ferric chloride to assure sufficient reactant available

3)Confirm your loading and handling procedures to assure that plates are not being blocked from getting fresh reagant (also that no air bubbles are forming to block reaction;

4) make sure that your process has proper circulation agitation and that it is effective throughout the workspace.

Milo

the process contain a lot of stages from the printing of the film until the printing of the desire shape on the plate then it is wash with Na2 Co3 then proceed to the etching machine and etched for 15 minutes depending on the desired base thickness.

Usually the plate is properly clean with caustic soda prior etching

Is there any appropriate properties for the etching solution when dealing with carbon steel plate?