Prepress field: incomplete planning of goods; poor printing composition; incomplete design; poor plate making; poor printing materials and so on.

Printing: printing effect is bad; hue is inconsistent: size allowed; printing adaptability; printing conditions bad; printing precision allowed; printing machine equipment is not complete; the printing machine printing workshop environment bad; bad etc..

Finishing: layered laminated bag is not good bad; adaptability; filling adaptability is not good; the bad after processing performance (boiling and steam sterilization); small light performance is good; adaptability can save bad circulation performance; Xiao Liang: convenient bad performance etc..

Printing waste, also called non drawing part phenomenon, refers to the phenomenon that the ink leaked from the scraper is transferred to the printing paper. It is a special fault in gravure printing.

Causes of fouling：

1, printing speed;

2, printing ink viscosity hard;

3, thinner dosage;

4, use a large number of 2 (standard), 3 (dry, slow) desiccant outside the solvent;

5, ink drying slow;

6, scraper in a wavy state, the blade out too much, scraper pressure is too large, scraper angle is not allowed;

7, roll around the roll is too thin.

Terms of settlement：

1, reduce the printing speed, reduce the viscosity of the ink to reduce the shearing stress:

2, increase the amount of diluent resin in order to improve lubricity;

3. Halt the use of super speed drying and slow drying solvent in an attempt to improve re solubility;

4, improve drying properties.

Of the above solutions, the first is the most effective strategy. In addition, we should also pay attention to the following matters:

1, roll circumference should be small;

2, the accuracy of the blade, grinding angle and so on;

3, excessive force applied to the scraper.

In short, a factor can not lead to the occurrence of failures, we should take into account a variety of comprehensive factors, and sum up comprehensive countermeasures. Electrostatic failure, which is the most difficult to explain clearly in most printing failures, especially in the recent emergence of a variety of printing paper, and the pursuit of high-speed printing, more prone to this phenomenon. The main friction electrification, electrostatic charging, discharge, flow of charged, crushing and mixing stripping charge charged charged and charged them and mixed, printing is the greatest friction, flow and stripping charged charged charged. Compared with other types of work, printing can be said to be very easy to produce electrostatic work. In the future, the countermeasure research of ESD will be an important management project.

Causes of static electricity

：

1, air and film friction;

2, film and guide liquid, press roller friction, stripping;

3, the film types are different, there are differences in electrification;

4, because the type of ink is not the same, there are differences in electrification;

5, the environmental conditions are different, there are differences in electrification;

6, the machine in addition to the power (ground) state is different, so there are differences;

7, printing speed, the difference of electrification.

Resolvent：

1, the state press roller to the printing paper operation angle is an obtuse angle, in order to reduce the stripping charge;

2, control humidity, avoid 50% to the environment humidity, should be controlled in more than 65% humidity, in order to reduce the flow electrification;

3, check the mechanical removal of static state, in order to reduce the friction electrification;

4, reduce the printing speed to reduce the stripping and flowing friction electrification.

The most common phenomena in electrostatic failure are "beard", "splash ink" and "moire pattern". It is necessary to pay attention to the treatment of all kinds of phenomena.

1 beard

Phenomenon: the bold, bold, and sharp positions of the printed part of the printed material, and the printing of the ink in the shape of the beard.

Countermeasures: generally improve ink viscosity, reduce printing speed, you can solve the problem. Now that the addition of the antistatic agent has not improved the results, the differential effect of the printed film may be taken into account.

2 splash ink

Phenomenon: a distance of several centimeters from the pattern, there is a fiber like ink flying occurs.

Countermeasures: reduce ink viscosity, using a fast and slow solvent mixed solvent effective.

3, moire

Phenomenon: in the field of printing, there is no obvious fog or circular appearance, especially the use of toluene ink, prone to this phenomenon.

Countermeasures: This is not associated with the viscosity of ink and printing speed. It is especially effective to add antistatic agent and a small amount of alcohol.

Scraper, 70% of the faults in gravure printing occur between the scraper and the roll.

Causes of scraper failures：

1, scraper wire

Appearance: an unrelated long line in a printed or non drawn line.

Reason: there is a foul dirt line between the scraper and the roller, which is mixed with foreign material, or the scraper is badly worn and damaged. Fine thick lines: hard inclusions cause damage to the blade: thick, thick lines: soft inclusions, double lines in the central part of the pattern.

Solution: the ink should be filtered before and after use; the scraper should be grinded or replaced; the circulating pump should be filtered during use.

2. Scraper dust

Phenomenon: the end of the field part, bold type, with filamentous dirt lines.

Reason: the inside of the scraper has a soft foreign matter accumulation, and at the end of the pattern, due to the transfer of the scraper, the foreign object is left out and the dirt line is produced.

Solution: remove impurities: ink filtering and cleaning the inside of the scraper; to reduce the viscosity of the ink; to install the scraper, you should pay attention to the length of the scraper, avoid the scraper is too hard or too soft.

3, no planning marks

Phenomenon: a 1-2cm high stain line is randomly generated in the design of a printed material or a non line drawing part.

Reason: small, soft inclusions from the blade and plate roll out of the gap, resulting in dirty.

Solution: ink filtration, re cleaning of the environment; the width of the print front roll shall be reset.

In the scraper fault, the inclusion is the most common phenomenon, and the thorough filtration of ink (150, 200 mesh) can prevent the dust from printing room mixing. Always pay attention to the printing room, environmental sanitation is also an important part of cleaning.