round dining table set,stone dining table,tables set,Home Furniture Kumusi (Dongguan) Furniture Co., Ltd. , https://www.coombesfurniture.com
Printing veteran teaches you how to eliminate the printing bar
Although the causes of bar defects in printing machines are complex, careful analysis can reveal underlying patterns and help identify solutions. Bars—also known as streaks or lines—can appear on printed materials due to various mechanical issues. Understanding these causes and implementing proper maintenance can significantly reduce or eliminate such problems.
a. Severe wear on the roller's driving gear or excessive tooth gaps can lead to bars. If foreign objects become lodged between the teeth or get stuck on the surface, they can cause uneven pressure and result in visible lines on the print.
Solution: Regular maintenance, cleaning, and inspection can prevent foreign objects from causing damage. Replacing worn gears or adjusting the gear alignment can also help avoid this issue.
b. Serious wear on the roller bearings can lead to misalignment and uneven movement, resulting in bars. This can affect the smooth rotation of the roller, causing inconsistencies in the printing process.
Solution: To reduce impact during gripping, you can adjust the paper padding in the blanket to create a trapezoidal shape. Alternatively, replace the bearing with a more wear-resistant one.
c. Excessive pressure between the plate cylinder and the rubber cylinder can cause large sliding friction. This friction can deform the ink dots and create ink buildup, leading to bars.
Solution: Adjust the pressure between the two cylinders carefully instead of simply adding more backing paper. Proper pressure ensures even ink transfer without distortion.
d. Inappropriate lining on the printing plate or rubber cylinder can lead to unwanted sliding friction. This friction may interfere with the normal gear drive, especially in areas with low pressure or thickly lined rubber rollers.
Solution: Reduce the linear velocity difference between the rubber and plate cylinders by adjusting the thickness of the rubber cylinder lining and increasing that of the plate cylinder.
e. Improper pressure on the rolling pillow can cause bars, especially in offset presses. The contact condition of the rolling pillow is closely related to the meshing of the gears. If the pressure is too high or the gears don’t mesh properly, vibrations can occur, resulting in lines on the printed material.
Solution: Readjust the rolling pillow pressure according to the manufacturer’s guidelines to ensure smooth operation and proper gear engagement.
f. Excessive pressure between the ink roller and the printing plate, or between the ink roller and the fountain roller, can cause bars. Similarly, high pressure between the water roller and the plate can also lead to this issue.
Solution: Keep the contact width between the ink roller and the printing plate within 6mm, and between the ink rollers within 5mm. Adjust the pressure between the water roller and the plate to minimize unnecessary force.
g. Misaligned or worn ink roller gears and intermediate wheels, as well as damaged ink roller bearings, can contribute to bar formation. These mechanical issues can disrupt the smooth operation of the ink delivery system.
Solution: Replace any damaged or worn components to restore proper function and eliminate the cause of the bars.
By addressing these common issues through regular maintenance, precise adjustments, and timely replacements, printers can maintain high-quality output and reduce the occurrence of bar defects.