How to solve ghosting in flexographic printing?
Date: Aug 19 2024 From: Star Color
Water based ink flexographic printing, as an environmentally friendly and efficient printing method, has been widely used in modern printing industry. However, in the actual production process, the problem of printing ghosting often troubles printing companies and operators. The phenomenon of ghosting not only affects the aesthetics of printed materials, but may also lower the overall quality of the product.
1、 Reasons related to printing machinery
Axial displacement of drum
The axial displacement of the printing cylinder is one of the common causes of ghosting. This may be due to the wear or looseness of the thrust bearing of the drum, causing the drum to move in series during operation. Especially in multi-color printing machines, if the axial fine adjustment mechanism is loose or the bearings are worn, there will be axial relative displacement between the plate cylinder and the rubber cylinder, resulting in ghosting.
Solution: Regularly inspect and replace severely worn bearings to ensure that the thrust bearings of the drum are in good condition. Meanwhile, for multi-color printing machines, close attention should be paid to the stability of the axial fine adjustment mechanism, and timely adjustments and maintenance should be carried out.
2、 Reasons related to printing technology
1. Improper pressure on the printing plate
The pressure between printing plates is one of the key factors affecting printing quality. If the pressure is too high and cannot be completely reset after each transfer, it will lead to the occurrence of ghosting phenomenon. On the contrary, if the pressure is too low, problems such as inaccurate printing may occur.
Solution: Reasonably adjust the pressure of the printing plate cylinder and rubber cylinder to meet the requirements of synchronous rolling. On the premise of ensuring ink transfer, appropriately reduce the printing pressure to avoid displacement due to excessive pressure.
2. Ink viscosity and fluidity
The viscosity and fluidity of water-based ink have a direct impact on the printing effect. If the viscosity of the ink is too low and the fluidity is too strong, it is easy to produce drawing phenomenon during the printing process, which can lead to ghosting.
Solution: Adjust the viscosity of the ink according to printing requirements, and add thickeners appropriately to improve the viscosity and stability of the ink. At the same time, maintain the cleanliness of the ink to avoid impurities from entering and affecting the printing quality.
3、 Reasons related to paper
1. Paper flatness
The flatness of paper is crucial for the printing effect. If the surface of the paper is too rough or has issues such as ruffles, it is prone to deformation under pressure during the printing process, leading to ghosting.
Solution: Choose paper with good surface flatness for printing. For paper with uneven edges such as lotus leaves, it should be dried or other methods should be used to make it relatively flat before printing.
2. Paper transport stability
The stability of paper during transportation is also one of the important factors affecting printing quality. If the paper transport is unstable, it is easy to cause offset or shaking during the printing process, leading to the occurrence of ghosting phenomenon.
Solution: Optimize the paper transport system to ensure the stability of the paper during transportation. At the same time, adjust the relevant parameters of the printing machine to reduce offset and shaking during paper transport.
4、 Other factors
1. Printing speed and environmental conditions
Excessive printing speed or poor environmental conditions (such as large temperature and humidity changes) may also lead to the occurrence of ghosting phenomenon. When the printing speed is too fast, the contact time between paper and ink is shortened, which may prevent sufficient drying and curing; Changes in environmental conditions may affect the drying speed of ink and the deformation of paper.
Solution: Adjust the appropriate printing speed based on the characteristics of ink and paper, while maintaining a relatively stable printing environment. In seasons or regions with significant temperature and humidity changes, corresponding measures should be taken to control changes in environmental conditions.
The reasons for the occurrence of ghosting in water-based ink flexographic printing are multifaceted, including printing machinery, printing technology, paper, and other aspects. In order to effectively avoid and solve the problem of ghosting, it is necessary to start from these aspects and take corresponding measures to adjust and optimize.
The
water-based flexographic ink produced by Huizhou Zhongzhixing Color adopts a high concentration, low viscosity formula, with moderate viscosity to fully ensure the quality of the ink. We use advanced production technology and quality control system to ensure the stability and consistency of each batch of products, meeting customers' demand for high-quality printing. Whether it's beautifully printed brochures, packaging boxes, or trademarks and labels that require high color accuracy, we can provide the perfect solution.
RU
EN
CN
