If you have any needs pls contact me-
Whatsapp number of Ivy: +852 57463641 (My Wechat +86 18933510459)
Email me: 01@songhongpaper.com
Introduction: The technical control of flexographic printing technology encompasses all stages of the production process. It is essential to focus on the appropriate selection of printing plate materials, the design of platemaking process parameters, and the control of key steps in the printing process. These elements must be comprehensively monitored and managed to effectively prevent quality issues during production, enhance print quality, and meet customer requirements.
1. Rational Selection of Flexographic Printing Plates
Flexographic printing plates differ significantly from those used in offset printing. Due to their relatively soft and elastic nature, these plates are prone to deformation under pressure. The printing performance of plates varies depending on their thickness and hardness. Thinner and harder plates exhibit lower deformation coefficients, which is beneficial for achieving higher print quality.
For printing high-resolution cartons, color boxes, and other fine-color products, a plate thickness of 2.84 mm is recommended. When printing on corrugated cardboard or other uneven substrates, thicker plates should be used. Otherwise, the shallow relief height of the plate may result in dirty prints and other defects.
Using thicker plates allows for compression deformation during printing, compensating for substrate irregularities such as uneven thickness or poor surface finish. This enables more uniform ink distribution on uneven surfaces, thereby improving overall print quality.
Resin-based flexographic plates are categorized into solid and liquid types. Differences in material properties and manufacturing methods lead to variations in cost and print performance. The selection should be based on specific production requirements.
Solid resin plates are semi-finished materials made from raw components. They are exposed to light, developed, dried, and sometimes re-exposed to produce finished plates. These plates offer convenient and rapid platemaking. Their thickness is highly uniform, and their expansion rate is significantly lower than that of rubber or liquid resin plates. With excellent ink receptivity, durability, and dynamic range, they are capable of reproducing fine highlights, high-gloss dots, and intricate text and lines. However, the material cost is relatively high.
Therefore, solid resin plates are typically more suitable for high-end, fine-detail pre-printed packaging such as cartons and color boxes. Additionally, from an economic standpoint, they become cost-effective only when used for large print runs.
Liquid photosensitive resin plates are manufactured from liquid photosensitive resin through processes including flow coating, back masking exposure, front exposure, full back exposure, recovery of uncured resin, development, drying, and post-exposure. The platemaking process is relatively time-consuming, usually taking about one hour. However, the raw material cost is approximately half that of solid resin plates.
Moreover, due to lower thickness precision and a higher deformation coefficient, the print quality of liquid plates is generally inferior to that of solid plates. Hence, they are typically recommended for short-run jobs with simple layouts.
2. Key Control Points in Flexographic Printing Processes
Flexographic plates are highly sensitive to printing pressure due to their soft and elastic characteristics. Excessive pressure can cause dot gain, text or line distortion, resulting in rough prints, double imaging, or blurred images, which negatively affect product reproduction quality. Therefore, flexographic printing can achieve uniform and rich ink density with relatively low pressure.
In addition to proper pressure adjustment, accurately controlling the contact pressure between the anilox roller and the plate surface is a critical technical factor. Excessive pressure between the anilox roller and the plate may lead to plate blurring due to over-squeezing of the ink layer. Conversely, insufficient pressure may hinder uniform and adequate ink transfer. Therefore, appropriate pressure settings must be ensured during plate installation.
Furthermore, during the printing process, it is important to adjust the printing speed according to the characteristics of the ink, substrate, and plate surface to maintain consistent ink color throughout the entire print run. For products with small print areas, using high-performance ink and premium substrate materials allows for a relatively higher printing speed. In contrast, when printing on large areas or with lower-quality materials, the speed should be appropriately reduced to achieve a saturated ink appearance.