TL;DR
Shear blades have four usable cutting edges. When cut quality degrades and gap adjustment no longer helps, rotate the blade to expose a fresh edge before ordering a replacement.
What you might see
- cut edge rollover increasing beyond 10 percent of material thickness
- blade chipping visible on inspection
- cutting force noticeably higher
- burr height on cut parts increasing
Likely causes
Blade edge worn past the usable dulling limit from cumulative cutting cycles
Blade nicked from cutting material with embedded scale or weld spatter
Excessive blade gap set too tight driving premature contact chipping
Blade material mismatch for the hardness of the plate being cut
Required tools
- Cut-resistant gloves (metal blade handling rating)
- Socket set and torque wrench
- Blade lifting tool or lifting fixture
- Paint pen or marker
- Safety blocks for the upper beam
- LOTO kit
Safety first
- Place safety blocks under the upper beam before any work in the blade zone. The beam can descend if hydraulic pressure bleeds off.
- Blades on large shears can weigh 30 kg or more. Use mechanical assistance and never carry a blade alone.
- All four edges of a shear blade are sharp. Handle blades with cut-resistant gloves at all times.
Procedure
- 1
Power off the shear, lock out the electrical disconnect, and place safety blocks under the upper beam.
Warning: Shear blades are extremely sharp on all four edges. Wear cut-resistant gloves rated for metal edges during all blade handling. - 2
Mark the current cutting edge orientation on the blade with a paint pen before removing, to track which edges have been used.
- 3
Remove the blade mounting bolts using the correct socket. Keep the bolts and hardened washers together for re-use.
- 4
Lift out the blade with a blade lifting tool or two-person team. Do not drop the blade.
Warning: Blades can weigh 30 kg or more on longer shears. Use mechanical assists or two-person lift protocol. - 5
Rotate the blade 90 degrees or 180 degrees to expose a fresh cutting edge, or install a new blade if all edges are spent.
- 6
Clean the blade seat and blade back surface with a wire brush. Any burrs or debris on the seating surface will misalign the blade.[1]
- 7
Install and torque blade mounting bolts to the value specified on the blade holder or in the Cincinnati service manual.[1]
- 8
Set the blade gap per the gap-setting procedure and make a test cut on scrap before returning to production.
Sources
Cincinnati Cincinnati CL Series Shear / Guillotine general technical documentation, Cincinnati
Cincinnati shear operator and maintenance manual, blade rotation and replacement procedure (general)
More guides for Cincinnati Cincinnati CL Series
How to set blade gap and angle on a Cincinnati CL Series shear
Ragged or burred cuts nearly always mean the blade gap is wrong for the material thickness. Set the gap to approximately 5 to 7 percent of material thickness and re-check blade parallelism.
How to fix hold-down clamps not clamping on a Cincinnati CL Series shear
If the hold-down does not clamp, check for a faulty hold-down pressure solenoid, low hydraulic pressure, or worn pad contact surface. Verify solenoid valve function before adjusting pressure.
Stop fixing the same fault twice.
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