Blanket in the printing process plays a very important role, the correct use and maintenance of rubber blanket can extend its service life. Below are several ways to use and maintain the rubber blanket~
Cutting of Rubber Blanket
Rubber cloth in the cut should pay attention to identify the direction of its strands (warp and weft), the shape should be rectangular. The direction of the warp and weft of the rubber blanket can be judged from the back of the rubber blanket dark-coloured weaving line towards (warp), the warp should be wrapped around the rubber drum to withstand a greater resistance to tension, so that the elongation is small, the print deformation is small. Whether the shape is rectangular, you can use a right triangle or diagonal equal to measure. Not rectangular rubber blanket in printing will produce torsional deformation.
Rubber blanket installation
When the Rubber Blanket is loaded into the clamp, a 2cm long marking line can be drawn with a pen on the Rubber Blanket gripper and the tip of the drag to check whether the Rubber Blanket is inserted into the clamp at the same depth. The amount of Rubber Blanket beyond the opposite edge of both clamps should be the same. When tightening the clamp screws, should be tightened from the middle to both sides one by one, pay attention to the same degree of tightness of the screws.
Originally encountered a case of local ghosting failure, the reason is that the apprentice in the screw Rubber Blanket plate clamps, screws are not from the middle to both sides of the tightening one by one, so that the Rubber Blanket expansion and contraction of the two sides of the inconsistent and caused by ghosting.
Plate clamps installed, should re-measure the parallelism of the plate clamps. Then the Rubber Blanket is loaded into the groove of the rubber drum tensioning shaft, and pay attention to the plate clamp screws in the tenon in the groove of the tensioning shaft to have an absences, so the Rubber Blanket grippers and towing the tip of the plate clamp screws in the tenon should be moved to the operating side or transmission side at the same time to prevent the occurrence of torsional deformation, and then after that the Rubber Blanket is tensioned. pay attention to the fact that the new Note that the new Rubber Blanket should be re-tensioned after a short period of time after being pressed together and rotated. The tightness of the Rubber Blanket can be identified by the sound of the Rubber Blanket being struck by the finger.
Cleaning of Rubber Cloths
The surface of the rubber blanket is mainly composed of synthetic rubber which is mainly non-polar. When observed under magnification, the smooth surface of the rubber blanket is fluffy. Therefore, in the printing process can maximise the adsorption and transfer of moisture. However, in the printing process, due to physical adsorption, the coating particles in the paper, plant fibres and pigment particles in the ink are easy to stay in the rubber blanket surface of the rubber layer of the fluffy pores, the formation of the masking layer. As a result of the masking layer of substances mostly polar substances, making the rubber blanket oleophilic decline, hydrophilic enhancement, resulting in the printing plate on the small dot can not be transferred to the paper through the rubber blanket. The field part of the powdery micro-fine spots, seriously affecting the quality of printing. On the other hand, the hydrophilicity of the rubber blanket to enhance the non-graphic part of the plate adsorption of the fountain solution more through the rubber blanket to the paper, resulting in paper elongation, overprinting is not allowed, as well as pulling the hair, powder and other printing faults. If the masking layer gradually thickened and hardened, and even produce "aurora" phenomenon, so that the rubber blanket local plastic deformation, destroying the uniformity of the thickness of the rubber blanket, printing other products are prone to the phenomenon of insufficient local pressure. Therefore, it is necessary to frequently and thoroughly scrub the rubber blanket, so that its surface always remain fluffy. As the blanket covering layer contains polar substances (paper powder, paper hair, etc.) and non-polar linking material, according to the principle of similar solubility, in the cleaning of the blanket first cleaned with water once, and then with a fast evaporating organic solvents (such as gasoline, etc.) for cleaning.
Rubber Blanket's Internal Consumption
Rubber blanket has good elasticity, different from the general material, rubber blanket low modulus of elasticity, deformation rate is large, stretching and compression will be exothermic. As the rubber blanket in the printing process by the role of cyclic alternating stress deformation, and always lag behind the change in stress, part of the elastic potential energy within the rubber can not be released in time, converted to heat release, this phenomenon is called internal consumption. The internal wear of the rubber blanket can not be avoided, so the temperature and humidity of the offset printing shop should be controlled and the temperature of the lubricant to reduce the temperature of the rubber blanket to reduce the thermal aging of the rubber blanket, for high-speed offset presses can be used for good elasticity, internal consumption of small cushion rubber blanket.
Maintenance of the rubber blanket
Correct use, good maintenance of the rubber blanket, you can improve its printability, prolong the service life, improve the quality of printing. To prevent the rubber blanket aging, you can start from the following aspects.
(1) diligent cleaning of the blanket, remove the paper dust, paper hair and other dirt, pay attention to the cleaning agent to be appropriate.
(2) If the downtime is long, to loosen the rubber cloth, so that it is in a state of relaxation, and in the surface of the talcum powder, which is conducive to its recovery of internal stress.
(3) The liner of the rubber cloth should be flat.
(4) Store the rubber cloth to avoid strong light, it is best to cover with black paper.
