Analysis and maintenance of the causes of dirty pre burned silkscreen
When adjusting the contact pressure of the water supply roller to the water scouring roller, we must pay attention to the symmetry of the eccentric bearing direction, otherwise, it will lead to the water roller and pre burned silk screen roller, the water scouring roller is not parallel, the lint of the water roller is easier to be pushed by the axial force into a spiral shape, and the water delivery is impossible to be uniform. If the eccentric adjustment of the two ends of the water roller is not symmetrical, it will lead to uneven pressure of the water roller, and the side of the pre-burned silkscreen will be more likely to get dirty. So when testing the pressure of the water roller, you can measure several places, both at the ends and in the middle.
The pre-burned silk screen soiling is divided into full plate and partial soiling, the reasons are many. Water glue roller and pre burned silk screen improper pressure adjustment, water glue roller sticky ink, wetting solution ratio is not appropriate, pre burned silk screen liner paper spread improperly and pre burned silk screen itself quality problems, etc., are more likely to make pre burned silkscreen is more likely to be dirty on both sides. In the printing process, there are times when the offset pre-burned silkscreen is dirty on both sides of the failure. The following is an analysis of the causes of pre-burned silk screen dirty on both sides.
In addition to the accurate adjustment of the water roller contact pressure, the water roller's daily reasonable maintenance is also very important.
First, in the usual offset printing operation, the water roller should be kept clean and free from oil and dirt.
Second, the water roller velvet cover should be kept often moist, with a certain amount of moisture.
Third, regular cleaning of the water roller. Water rubber roller can be cleaned then wash, too much oil, can not be cleaned, to timely replace the new water velvet cover, so as not to pre burned silkscreen up dirty. Another way to effectively prevent the water roller sticky ink, that is, when printing, the water bucket solution with a small amount of hydrocolloid material - gum Arabic, can effectively increase the hydrophilic water roller, with a sponge and other hydrophilic materials will be emulsified in the water bucket solution wipe clean, the water roller surface of the dirty ink adsorbed.
pre burned silk screen liner size is too small
In general, pre-burned silkscreen underneath is to add liner paper, in order to avoid pre burned silk screen liner paper on both sides of the wet into the water, the horizontal size of the liner paper will be smaller than the pre burned silkscreen size. But the size of the liner paper is too small will cause insufficient pressure on both sides of the pre-burned silkscreen, resulting in poor contact between the pre-burned silkscreen and the water roller and dirty.
Elimination method: when cutting pre burned silk screen liner paper, the horizontal size control in the pre burned silk screen than the small 10 ~ 20mm range, in order to prevent damage to the liner paper due to water, can be coated on both sides of the pad paper or a layer of mortar and butter, machine oil, the use of oil and water repulsive reason, to avoid the liner paper wet, to improve the use of the effect. Paper wetting, improve the use of the effect. If the liner paper of the roller is wet, it is easier to make the shell of the roller corrode.
The two heads of the watering roller sticky ink reduce the performance of water transfer pre burned silkscreen plate if the two heads of water control too little, it will cause the water supply is not enough to make the two heads of the watering roller sticky ink, causing the two sides of the pre burned silkscreen up dirty.