Gravure printing plate fault analysis and troubleshooting - not allowed to register

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There are many factors that affect overlay accuracy in gravure printing, such as the stability and reliability of the main motor and its control system, the transmission form and accuracy of the gearbox, the balance of the dynamic and static balance of the paper guide roller, and the sensitivity of the electrical system. Reliability, illegal operation of the equipment during use, wear of the mechanical system without maintenance, local deformation, etc. This mainly analyzes some factors related to the printing roller.

(A) The mechanical precision of the roller

At present, the mechanical precision of the printing roller manufactured by the plate makers generally meets the following requirements:

Project requirements

Length limit deviation ±0.2% of roll length

Diameter limit deviation ±0.02 mm

Wall thickness 6 mm-12 mm

Keyway width depth limit deviation +0.3 mm


Taper taper limit deviation ±1°

The cylindricity is not more than 0.03 mm

Flange fillet 7 mm~11 mm

Dynamic balance below 80 g (1200 r/m)

One of the reasons for overprinting accuracy is the poor accuracy of the roll.

The single-chamfer machine currently has two forms of a plate with a shaft version, a hollow version.

1. With axis version

Spindle plate costs high, but machining accuracy is also high. Because the plate-shaping platemakers have to go through an imported MDC grinding machine during machining, on the one hand, the precision of the grinding machine is high. On the other hand, the reference point for grinding is the same as the reference point for printing, so the mechanical accuracy of the printing roller high.

2. Hollow version

The cost of the hollow version is slightly lower, but due to the fact that the processing standard at the time of plate making is difficult to be the same as the printing standard, and secondly, even if the plate making is consistent with the printing standard, there are cases where the operator does not regulate the wear of the shaft or the long-term removal of the wearer's shaft, especially the brutal disassembly. Axial damage is caused, so that after the actual wearing of the shaft, the roller around the jump out of tolerance, out of roundness, etc. are the main reason for overprinting is not allowed.

(b) Effect of the direction of paper strands on overprinting

In general, the lateral expansion of paper fibers is much larger than the longitudinal expansion of paper fibers, which is generally 2-8 times. Therefore, the transverse elongation of the paper fibers is also much greater than the longitudinal elongation. Straight silk 缕 paper printing refers to the direction of the printed paper fiber and the drum rotation direction. Cross-hitch paper printing refers to the direction of the paper fiber and the roller axis. Straight silk 缕 paper from the boot to the end of printing, the paper's expansion and contraction is more horizontal than the vertical, after the printing of paper images appear prone to horizontal overprint is not allowed. After the horizontal silk file is printed, the paper's expansion and contraction changes are greater in the longitudinal direction than in the horizontal direction. After the printing, the vertical and horizontal images are liable to be misprinted. Therefore, what type of silk paper is used for printing, and the amount of change in the shrinkage of this silk paper must be provided to the platemaking company.

(III) Plate-making company has an overall zoom function in the electric engraving section

Depending on the fixed variation of the paper web, the overall horizontal or vertical scale can be used to compensate for the changes caused by the paper strands.

(4) Use Trap (Match) to make up for overlay error

Fundamentally speaking, the purpose of the capping technique is mainly to compensate for overprinting errors in the printing press. (Because there are mechanical errors in even more precise presses). The method of contraction is divided into inward contraction and outward expansion.

1. Shrinkage (color printing process is generally from shallow to deep)

The shrinkage of the cap is to shrink the uniform color within the next color to the next color of 0.05 mm to 0.1 mm. For example: Under the big red, shrink the yellow line. Under dark purple, narrow the red line. However, the internal shrinkage is generally applicable to a pattern with a large area of ​​two colors, and a small pattern is not applicable.

2. External enlargement (color printing for surface printing is generally from shallow to deep)

In the practical application of external expansion of the cover a lot, where the adjacent color are generally extended shallow depth 0.15 mm ~ 0.3 mm, make up the overlay error caused by adjacent two color dew white seam quality defects, so that the yield greatly improved.

Application: It`s a slit equipment with high precision and high sensitive and function for detecting unhealthy basic film or aluminium film. Running performance is stable, easy to operate, visual, and high automatically degree etc advantages. It can meet different slit width and using demand from client. It`s the necessary equipment in printing, packaging, food, pharmecutical. 

Inspection Machine Series

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