[Discussion] Why Is Color Registration on Gravure Printing Presses Always Unstable? Jittering and Slow Response?

Pingchangxin: Why is color registration on the gravure printing press always unstable — jittering and slow to respond? Is it poor mechanical performance or a problem with the computer system?

Zhou of Hangzhou Chaoyang Color Printing: Turn off automatic color registration. If there is no fluctuation, then it is a precision issue with the color registration controller; if the fluctuation is large, then check the guide rollers, bearings, locating pins, etc., and it is best to have the manufacturer inspect it. But what a printing press is really all about is tension — remember that tension and temperature must be moderate and must never be too high.

Pingchangxin: When we print, the machine's color registration is always jittering. Every time we start registration it is unstable, and the computer tracking is unstable. After about 1000 meters of printing, it is basically normal! I don't know what the problem is. We generally print PET, at a printing speed of 90m/min, with around 6 colors. The copper cylinder circumference is around 450, the tension is quite stable, but sometimes when the computer registration is started normally, it suddenly loses tracking! Sometimes it jitters for no reason! It only stabilizes after the machine has been running for a while.

Ma of Dongguan Yingcai Packaging: If the actual color registration is fluctuating and the computer follows the change, and the variation index matches the color mark, that means there is no problem with the computer.

If the wave gate is unstable, check whether the wave gate peak is very small. If it is, you can replace the electric eye. If replacing the electric eye still does not solve it, open the color registration electrical cabinet. At the bottom of the color registration electrical cabinet, each color unit has a module in which the sensitivity of the optical wave gate can be adjusted.

Also, look at how the jitter in your color registration manifests — is it all of it or only part of it? This can determine whether it is the color unit or the tension.

If it occurs in a single unit, you need to inspect all the guide rollers between the color units as well as the enclosure of the color unit, especially the chill roller. If it occurs in all units, then check whether the nip roller of the first color (under stable tension) is balanced and whether it is slipping (pay special attention to the infeed traction), or whether the tension of the outfeed tension is causing trouble. Check whether the nip roller of the last color (and the outfeed traction nip roller) is slipping. Also check the electrical cabinet (main machine) and carefully examine the conditions on both sides of each frequency converter — this requires knowledge of electrical systems to determine.

Actually, solving the problem is just quantitative elimination — it is very simple. You will understand after encountering it once or twice; equipment is actually very simple.

Pingchangxin: Thank you very much. I will try them one by one. (If you have different opinions, you are welcome to continue the discussion at Packaging Frontier Network www.pack168.com. You are also welcome to continue exchanging views on our website. Friends who provide more solutions can receive reading credits for technical articles on the website. To request credits, please contact Xiaoyang: 15813331361 and Xiaolai: 18475695660.)