Causes of Gravure Registration Variation and Corresponding Measures

Fluctuations in Register Caused by Electrical Faults

Generally speaking, the electrical part of the register system in gravure printing machines consists of detection parts, processing devices, and actuating mechanisms. Any malfunction in these components can cause fluctuations in register. Therefore, to analyze the reasons behind these fluctuations, one must have a thorough understanding of the electrical principles of the register system.

When checking for register fluctuations caused by electrical faults, a common method is to follow the path step-by-step. Based on an understanding of the electrical principles of the register system, each related electrical component and circuit can be checked progressively for normal operation. However, with considerable experience in adjusting the register of a specific gravure printing machine, one can also adopt a more intuitive approach, which can quickly identify the point of failure.

Fluctuations in Register Caused by Mechanical Faults

From practical experience, there is no fixed method for checking the mechanical aspects of the register system. Only with an understanding and mastery of the mechanical parts of the gravure printing machine, knowing which mechanical structures affect register, can one quickly find the root cause. Of course, since mechanical faults are usually more apparent than electrical faults, discovering register fluctuations caused by them is relatively easier.

For example, after long-term use, the surface of impression cylinders shows obvious wear marks, which can affect register accuracy. The thinner the substrate, the greater the impact on register accuracy. Additionally, if an impression cylinder is observed to vibrate up and down continuously during printing, it is likely due to bearing damage, which affects the longitudinal register of the printed products.

Similarly, if the plate cylinder is not locked tightly, it can result in minor lateral shifting, often causing sudden lateral register jumps. Furthermore, lateral shifting of the paper guide roller, problems in the stepper motor transmission, etc., can also cause register fluctuations. These types of register faults are generally characterized by large, sudden register jumps occurring intermittently during production.

Fluctuations in Register Caused by Other Factors

Apart from electrical and mechanical reasons, other factors causing register fluctuations should not be overlooked.

Firstly, improper operation can cause register fluctuations. For example, if the tension setting is inappropriate, the paper web will relax and tighten intermittently during high-speed operation, affecting longitudinal register. Similarly, if the oven temperature is set too high, it can cause excessive deformation of the paper after passing through the oven, affecting the register of the next color.

Secondly, raw materials and production environment also affect register. Overly loose paper can cause frequent changes in actual tension, increasing the difficulty of operation. This usually manifests as longitudinal register inaccuracies. Uneven paper edges can cause the paper guide system to operate continuously, affecting lateral register. The temperature and humidity conditions of the production environment can have a certain impact on the degree of paper deformation during printing.