The use and maintenance of printing rollers

After two or three years of use, the water and ink rollers of each printing unit of a printing press will gradually exhibit various quality issues, affecting the transfer performance of the water and ink paths and significantly impacting the printing quality of newspapers. This also creates inconvenience for daily maintenance and upkeep of the rollers. Below are some common problems and solutions:  

(1) Rollers should not be stored near large electric motors or generators. The large amount of ozone produced by these devices can cause the roller surface to age and crack.
 
(2) In cold weather, if the ink is uneven, appropriate auxiliary materials can be added to the ink. Do not use infrared heaters or other equipment to bake the ink rollers to prevent oxidation.
 
(3) Printing rollers in offset printing presses primarily transfer ink. Therefore, when cleaning the rollers daily, they must be thoroughly cleaned. Otherwise, the surface layer of the rollers and the pigments and resins will oxidize to form a smooth, hard film, causing surface glazing and affecting ink transfer. If they are not cleaned frequently, the roller surface will become uneven over time and difficult to use. Therefore, when the machine is stopped, the rollers should be cleaned and stored for later use.
 
(4) To ensure that production and printing quality are not affected, spare ink rollers must be available, but excessive storage should be avoided to prevent aging. The storage environment for rollers is the same as for rubber blankets. In addition, rollers should be placed horizontally on their journals, and their surfaces should not come into contact with each other or other items to prevent deformation.
 
(5) Rollers that have been used for a long time and have aged, coupled with chemical corrosion, resulting in the roller material deteriorating and flaking, should preferably not be used anymore, otherwise, it will seriously affect the quality of the printed matter.
 
(6) In offset printing operations, ink emulsification caused by "too much water and too much ink" creates a hydrophilic base on the smooth rollers, causing them to lose ink. The solution is to remove the emulsified ink, clean the ink-losing rollers with gasoline, and polish them with a mixture of 5% sodium hydroxide solution and pumice powder. The metal rollers (or hard rollers) should also be treated accordingly. Hard rollers can also be polished with fine water sandpaper while being sprayed with water. Note that the sandpaper should not be kept stationary in the same position, otherwise, the rollers will be damaged. The fundamental solution is to control the pH value of the fountain solution and maintain good water-ink balance.  

Flexographic printing uses flexible printing plates and a screen roller to transfer ink. In recent decades, it has seen significant development worldwide, with its printing technology becoming increasingly mature and its applications expanding to include labels, flexible packaging, and cartons, even extending to publishing. It can be used for printing on almost any substrate. The printing plates used in flexographic printing are elastic. When a flexible printing plate is mounted on a printing cylinder, it will bend and deform along the circumferential surface of the cylinder, causing a dimensional deviation between the printed image and the original.

Dongguan Xinhe Electromechanical Co., Ltd. [ www.dg-xinghe.com ]