Doctor Blade Wear Cause and Solution
Doctor Blade Wear Types, Causes, and Treatment Methods
Uneven wear, frequent replacement of doctor blades
Possible reasons:
The surface of the roller or dryer cylinder is uneven or has improper hardness; a blade that is too hard will damage the roller surface.
The doctor blade holder is damaged, dirty, or lacks sufficient support, preventing even pressure across the entire width of the blade.
Pulp deposits, adhesive, and other debris on the roller surface can also cause localized wear of the blade.
Improvement methods:
Use a softer doctor blade.
Clean, repair or replace the doctor blade holder.
Use a corrosive doctor blade.
Excessive wear on the middle or edge of the doctor blade
Possible reasons:
The installation position of the doctor blade is not at the top of the roller.
The old blade sinks (or leaves) the roller or dryer.
Improvement method:
Modify or add shims behind the blade if necessary.
Replace old or sunken doctor blades.
Excessive wear on one end of the doctor blades
Possible reason:
The displacement of the doctor blades is not parallel to the axial direction of the roller or dryer.
Improvement method:
Add shims, and if necessary, move the bearings and brackets to adjust the doctor blades to be parallel to the axial direction.
The doctor blades is uniformly worn and the single end surface is rough
Possible reasons:
Sediments on the surface of the roller or dryer.
Excessive pressure on the doctor blades.
Doctor blades material too hard.
Improvement method:
Use a corrosive doctor blades when needed.
Reduce pressure.
Use a slightly softer doctor blades.
Excessive wear in the paper area
Possible reason:
Sediments left on the paper sheet on the roller or dryer
Improvement methods:
Use corrosive doctor blades when needed.
Regularly trim the edges of the blade.
Use end slotted blade to prevent excessive pressure at both ends of the roller or dryer.
Excessive wear outside the paper area
Possible reason:
The paper has lubricated the roller or dryer.
Improvement method:
Use doctor blades with a slotted end to release pressure.
Local depression
Possible reasons:
Doctor blade damaged by collision, electrostatic discharge/electrolysis/heating.
Improvement method:
Insulate the doctor blades from the frame or use a non-metallic blade.
Blade generates burrs
Possible reasons:
The blade material is too soft.
The pressure is too high.
The blade angle is too small.
Improvement method:
Use a slightly harder doctor blades.
Reduce pressure.
Adjust the bearing or bracket to increase the angle, and use an instrument to check and correct the angle.
If you want to choose suitable doctor blade for your paper machine, welcome to contact us to get more details solution.
