Definition - What does Doctor Blade mean?
A doctor blade is a mechanical device used to remove excess ink from a printing cylinder. While it removes some ink, it allows some to stay on the cylinder, thus metering the amount of ink that leaves the cylinder. As with most metallic devices, they are subject to wear and corrosion.
Corrosionpedia explains Doctor Blade
A doctor blade is an essential part of printing with a cylinder cartridge. The term "doctor blade" is thought to originally come from the German term "ductor blade".
Doctor blades can be made of either a plastic material or a metal such as steel. The thickness of different types of doctor blades can vary greatly; generally they are not over 1/16 inches (1.6 mm) thick.
A doctor blade helps to make a uniform print. Without a doctor blade, a printing cylinder would be likely to distribute uneven amounts of ink and ruin the surface on which the printing is occurring.
Doctor blades must be changed over time as they can wear and become ineffective at maintaining a uniform distribution of ink. It must be ensured that the doctor blade is at the correct angle, in the correct position relative to the cylinder and that it has adequate support to maintain its position, otherwise the doctor blade may not function as desired.