Frequently Asked Questions about Stick Faults in Flexo Printing

Q: How to solve the problem of ink marks in flexo printing? We use the machine foot Heidelberg GALLUS 410. Anilox rollers, stainless steel squeegees and machines are new and there are no vibration issues. The color of the prints is deep and shallow, especially the dark blue prints on the ground.

A: Is the printer equipped with a squeegee? Is it a dark ink bar or a light-colored ink bar? I have the same problem. If the anilox roller does not have a squeegee, check the roundness of the rubber roller, the wear of the roller gear and the bearing, and check the anilox roller if it has a squeegee blade. Machine oscillations also produce ink sticks.

Your problem is probably caused by gear meshing. It is also a toothed bar. It is easy to appear when the gear bar has a low speed. It should be said that the machine of GALLUS is helical gear meshing, and the chance of occurrence of gear bars is small. As far as I know, helical gears certainly do not have ink sticks at high speeds, but at low speeds, it is easier to produce ink bars than straight teeth, and it is difficult to eliminate the ink bars by changing the meshing relationship of the gears. You can try to see if there are no ink bars at 80 to 90m/min. Then make a judgment.

At least you say it's obvious when printing dark blue on the ground. Actually not the printing color is different, the size of the ink stick will be different. There is a saying in the printing industry that "blue ink does not hide ugliness," which means that when printing, a slight problem with blue ink will appear ugly. The same is true for green ink.

Q: We used two plates, 164 teeth and 159 teeth when printing the same product. With the 159 tooth plate roller there is no ink bar and there is 164 teeth. What's going on here?

A: This should be divided into two scenarios:

If your product is the same and only a different version of the roller is used, the number of gears with a larger number of teeth must be more in the neutral position of the platen. For example, if you print a Red River soft pack, 159 teeth can be completely wrapped in one week, and the neutral position of the edition mouth may be only one point, such as l0mm. When you use a 164 tooth roller, your neutral position becomes 10+3.175×(16+4-15.9)=25.8m. Then when the plate roller rotates one revolution, it will be more than twice the time in the neutral position. To know that this extra space, the roll rotation may be unstable, it is not surprising that the ink stick is generated.

Solution:

1. Bold balance line;

2. Paste in the neutral position cut from the waste plate for the vibration generated by the balance roller during rotation;

3, the pressure is not big.

Second, if the two sets of roller prints do not have the same graphics, you must first eliminate the first reason. Second, you can observe when your cross cutter blade comes into contact with the bottom roller. If it is, then the reason for the ink stick is definitely because of the vibration of the cross cutter. This kind of vibration has a very large effect at low machine speeds.

Solution:

1. Turn the knife of the cross cutter down to just cut the paper as well. It is better to produce vibration. This may require a little patience and skill;

2. Increase the speed of the machine. Above l00m/min, there must be no ink bars.

3, the printed paper through the paper to change the line, so that when the cross-cutting knife cut, the version of the mouth on the version of the roller just in the printing of the combined position, which is not to give it the opportunity to produce ink bars, we call it " Cutter bar."

I don't think that the saying that a die cutter roller vibrates to produce an ink stick does not necessarily make sense. The position of the die cutter is more than five meters away from the location of the printing unit that produces the ink bars, and our machine has a rotary screen that can only reach up to 60 m/min.