Doctor Knife / Doctor Blade

A doctor knife (or doctor blade) is a precision scraper used to remove filter cake, residue, or film from a moving surface such as a belt, drum, or roll. The blade’s geometry, pressure, and material determine how cleanly and gently the cake is separated without damaging the underlying cloth or support. Common materials include stainless steel for durability and polymers such as PU or PTFE where flexibility or chemical resistance is needed. Blade angle and contact pressure must balance complete removal with minimal wear and energy. In continuous belt filters and rotary drum filters, correct doctor blade adjustment ensures consistent discharge, dryness, and cloth lifetime. Poor alignment leads to streaking, uneven wear, and pressure fluctuations. Routine inspection and sharpening schedules maintain stable process performance.