Engraving and printing companies use doctor blades to wipe ink from their anilox rolls. They are used in both flexographic and gravure printing. This small part has a big impact on print quality, and it is important to know what they are. Here are some facts about these blades that can help you learn more about them.
These plastic or metal blades are designed to remove the ink from the non-engraved portions of an anilox roll. They are designed so the blade will wear down over time rather than the anilox roll. This is because blades are cheap, while anilox rolls are costly. Typically, these blades will be made from steel or plastic.
One important factor about these blades is the shape of the tip that comes into contact with the anilox roll. The three main tip shapes include straight, lamella, and bevel. Straight blades have a blunt tip and provide the lowest quality prints. Beveled blades have an angle so that a tip contacts the roll. A lamella has a pointed tip and uses a step design to widen the blade. Bevel and lamella tips provide high-quality prints.
To keep the wear patterns even, printing machines use oscillation to rotate their doctor blades. During oscillation, the blade assembly will rotate side to side in the printer. While this is designed to extend blade life, if problems occur during the oscillation cycle, the print quality can be lowered.
Doctor blades are quick and easy to replace. On most machines, a technician has to remove the blade holder, discard the old blade, install the new one, and reinstall the holder. Additionally, there are removal tools that make this process safer for technicians.
Doctor blades are a necessary part of the printing process that impacts the quality of a print. Because of their importance, it is important to know some basic facts about them.