Nickel & chrome plating Q&A for rotogravure cylinder problems

A. Christopher,

Grinding chrome must be done carefully; when you start the first cutting don't remove more than 2-4 µm per minute. The grinding stone shall be soft on hard material like chrome. Also scratch the grinding stone often. Because if the grinding stone contains chrome this will give the chrome deposit some fretting. After grinding operation you can lap the area with a diamond charged polish.

Regards,

A. Hello, Bhavesh! Sorry but you won't get sufficient training through an internet posting. If you are new to plating you may want to start with some books from our books page, and join the Indian Assoc. of Metal Finishers. You could also ask a finishing consultant or some finishing equipment suppliers to visit you as a productive first step. Good luck!

A. Hello,

I work for one of the leading manufacturers of Machinery and Process Technologies in Rotogravure Industries. I might can help you due of my work as Process Engineer in this Industry.

Best regards,

A. Costing: Although many construction trades have "fake books" to give you estimated times & costs for various operations, I've never seen one for electroplating. Instead, your cost estimates come from the other direction, i.e., you tabulate your plant's total operational costs and then you try to assign chunks of that to the various operations that you are doing.

Thickness measurement: You can measure the copper with thickness gauges of different types or by weight of the finished cylinder, and you can estimate the copper thickness in progress with amp-hour meters. The question sounds backward, though: there should be a spec for the copper thickness and your instrumentation should be directed at measuring how close you are coming to the optimum specified thickness.

Printing life: We've nothing to go by on your chrome life, Bhavesh. We don't know if your method is inadequate or your life expectations are too high. Since your company is new to this, I'd suggest calling in a local expert to get you started on the right foot. Good luck.

A. We make gravure cylinders in the UK. We plate 6 microns of chrome onto the engraved cylinder. This will easily last for 6 million copies (our biggest run). The cylinder must however be roughened in the copper and the chrome polish cycle to carry ink for lubrication. It is also important not to have the doctor blades applied with excessive pressure. These are by far the biggest causes of wear on our cylinders. If you still need help, it's not a problem.

A. Hi there,

How much is the thickness you do for Acid copper and also let us know the chemistry you use in Chrome , is it a catalyst bath or a conventional type , you can increase the hardness by using a organic kind of catalyst in chrome bath.

Regards

A. Hi, G. You might as well ask how to manufacture airliners or TV sets as how to manufacture rotogravure cylinders :-)

Sorry, such questions may be partially answerable by a whole book, can't be answered in an internet posting. You might want to retain a consultant to sit down with you for several days and begin planning. Then when you get to the point of specific questions, readers will probably be happy to try to help you. Two readers on this thread have already said they would like to help; but while they can answer questions for you, they can't possibly explain the whole business of rotogravure cylinder manufacturing top to bottom.

Please get back to us with questions that are more specific. Thanks!

Regards,

? Nkosikona,

You have a problem chrome peel off OR wiped off; your question is incomplete -- are you plating hexavalent or trivalent chrome or chrome flash on part? What is process to plate the chrome?

A. Sathya,
There is a very high probability that you have an oil layer on top of your degreasing tank. You are basically oiling the part when you take it out of the tank.
Another possibility is bad rinsing.
Be for a degreasing tank says nothing as there are hundreds of formulations.

A. Christopher,

I cannot see how your cells are damaged unless you are grinding an engraved cylinder before chrome plating. If you are doing this why? Grind the copper base to achieve Rz 0.3-0.6 (normally stones),engrave, chrome plate(6 microns), polish with paper or rough stone.

Praveen,
More information is needed; a more detailed description of the problem and your process. Do you or your customer have problems with other customers/suppliers. Check your roughness testers are calibrated properly. Have a look at your finish under magnification do you have turning lines from machining, what is your chrome like?

Polishing or grinding is the most important step in the process. Printers will also blame the cylinder maker for any problems so it is essential to work together. Doctor blade settings, ink, heat, humidity, substrate etc will effect printing so don't loose your customer work with them.

A. Dear all,

The better value to determine roughness is the Rz and the Ra as a comparable value.

As a cylinder lifetime it is not helpful to talk about the weight of the printed substrate rather than the meters printed.

If the chrome wears out fast, then these questions should be answered by the cylinder manufacturer:

- Is my chrome solution within specification?
- Is my chrome deposition good enough?
- Are my cells prior to chrome plating clean?
- Where is my roughness?
- Are my engraved cells within specs?

As a printer following should be answered:

- How are my doctor blade settings?
- Do I have premature drying ink in the cells?
- Is the doctor blade oscillating?
- Which cylinder regarding to type of ink is being rejected?
- Which substrate is printed and what are the temperatures of substrate?

Etc., etc., etc.