The anilox roller, also known as the metering roller, is a critical component in flexographic printing systems. It plays a vital role in the ink transfer process by ensuring precise and uniform ink distribution to the printing plate. But what exactly does it do? What parameters define its performance? And how should it be properly used and maintained?
1. Structure and Types of Anilox Rollers
Anilox rollers are composed of several key parts. The main components include the roller core, base material, and surface coating. The base material is typically electroplated copper, which serves as the foundation for engraving the cells and walls on the roller. The surface layer is often made of chrome or ceramic, enhancing wear resistance and preventing solvent corrosion from reaching the copper layer underneath.
There are two primary types of anilox rollers: metal chrome and ceramic. Ceramic anilox rollers are more widely used due to their superior engraving accuracy, better ink transfer, and improved ink release. They are also more durable and resistant to wear over time.
The manufacturing process for metal anilox rollers involves: metal base → copper plating → engraving → chrome plating. For ceramic anilox rollers, the process is slightly different: metal base → copper plating → engraving → sandblasting → ceramic spraying → polishing. Another method involves applying ceramic directly to the base and then using laser engraving, which ensures higher precision in cell formation.
2. Key Parameters of Anilox Rollers
The performance of an anilox roller is determined by several important parameters that affect ink storage, transfer, and print quality:
1. Cell Shape
Common cell shapes include quadrangular pyramids, hexagonal pyramids, and spiral patterns. Quadrangular pyramids are commonly found on metal anilox rollers and are produced through electronic engraving. These cells hold more ink and provide better ink transfer and release.
2. Line Count
Line count refers to the number of cells per inch along the roller's length. This is different from screen ruling in printing. While line count doesn’t directly determine image clarity, it significantly affects ink delivery and print quality.
3. Cell Angle
Depending on the engraving method (electronic or laser), anilox rollers can have 30°, 45°, or 60° cells. Laser-engraved cells are usually 60° hexagonal shapes.
4. Cell Opening, Depth, and Openness
Cell opening is the width of the cell’s top, while depth is how deep the cell goes. Openness is the ratio of depth to opening, typically between 23% and 33%, with 28% being ideal for optimal ink transfer.
5. Cell Volume
Cell volume measures the amount of ink that can be stored per unit area. It is expressed in BCM/in², where 1 BCM/in² equals approximately 1.55 cm³/m². This parameter determines the ink capacity of the roller.
3. Factors to Consider When Using Anilox Rollers
1. Choose the Right Ink Volume
The ink volume directly affects the amount of ink supplied to the printing plate. Different print jobs require different levels of ink, so selecting the appropriate volume is crucial.
2. Select the Right Line Count
Higher line counts mean smaller cells and less ink delivery, but better uniformity. However, too many lines can lead to the "edge effect," where corners of the cells block ink flow. A general rule is to use an anilox line count about four times the screen ruling of the printing plate for optimal results.
3. Match the Cell Shape to the Ink Supply System
Quadrangular pyramid cells work best with double-roller ink systems, while flat or hexagonal cells are suitable for scraper-type systems. The shape should also match the type of ink being used—angled cells help with high-viscosity inks.
4. Choose the Right Cell Angle
Most anilox rollers use 60° hexagonal cells, but special applications may require other angles.
4. Maintenance of Anilox Rollers
Proper maintenance is essential to extend the life of an anilox roller. Here are some key practices:
1. Use Protective Sleeves When Storing
Protective sleeves help prevent damage from vibration and keep the surface clean during storage.
2. Monitor Ink Viscosity and Clean Regularly
Blockage often occurs due to fast-drying ink or inadequate cleaning. Keeping ink viscosity consistent and cleaning the roller promptly helps maintain performance.
3. Use High-Quality Scrapers and Filters
High-quality scrapers reduce wear, and magnetic filters in the ink tank help remove impurities, extending the roller’s lifespan.
4. Inspect with a Mesh Microscope
Regular inspection with a mesh microscope can detect scratches or clogs early, allowing for timely repairs and preventing print defects.
oval dining table,nordic tables,Stainless Steel Dining Table
Kumusi (Dongguan) Furniture Co., Ltd. , https://www.coombesfurniture.com