| Blade Appearance and Symptoms |
Probable Causes |
Remedy |
 |
 Poor roll surface.
Damaged or dirty blade holder.
Deposits. |
Use more flexible blade.
Clean, repair or replace holder.
Use abrasive blade. |
| Uneven Wear - frequent Blade Change |
 |
Doctor not machined to match roll crown.
Old doctor sagging into/away from roll. |
Refit and shim holder to doctor back as necessary. (Return new doctor for replaning if mismatch is excessive.)
Replace old, sagging doctor. |
| Excessive Wear in Center of Blade, or at Ends |
 |
Doctor misaligned - not parallel to roll axis. |
Shim, or move bearings and brackets as necessary to align doctor parallel to axis of roll |
| Excessive Wear on one End |
 |
Deposits on roll.
Excessive pressure on blade.
Blade material too hard. |
Use abrasive blade as required.
Reduce pressure.
Use softer blade. |
| Even Wea But Rough Edge |
 |
Deposits left on roll by sheet. |
Use abrasive blade as required.
Trim blade edges frequently.
Use end slotted blades to prevent build-up of excessive pressure on roll ends. |
| Excessive Wear in Sheet Run |
 |
Sheet lubricates roll |
Slot blade ends to relieve pressure. |
| Excessive Wear Outside Sheet |
 |
Blade attacked by
Electrostatic discharge
Electrolysis,
Heat |
Insulate doctor from machine frame or use non-metallic blade. |
| Localized Pitting |
 |
Blade material too soft.
Excessive pressure.
Blade angle too flat. |
Use harder blade.
Reduce pressure.
Move bearings or brackets to increase angle. Check for correct angle with gauge. |
| Blade Develops Feathered Edge |
 |
Blade overhangs roll
Not centered.
Too long.
Not oscillating properly. |
Center blade
Trim Length.
Adjust oscillation stroke. |
| Hooks on Blade Outside Roll Surface |
 |
Blade caught scab on roll at start-up. (Most common on old dryers.) |
Change blade and remove scab. |
| Dent in Blade Edge |
 |
Blade pressure changed after initial wear-in; (opens blade tip to trap particles and lift blade - may cause wrap. |
Reduce blade pressure or change blade. |
| Increasing Pressure Increases Deflection |
