Scrap Metal Cutting Blades: Guillotine Shears vs Alligator Shears

Scrap metal cutting blades are some of the toughest cutting tools in any recycling operation. They cut through steel profiles, aluminum sections, copper pipe, sheet metal, and structural scrap that would destroy any other type of blade. Choosing the right blade and keeping it properly maintained determines throughput, cut quality, and how often your shear is out of service for blade changes. This guide compares guillotine shear blades and alligator shear blades and explains what to look for when specifying either type.

How Scrap Metal Cutting Blades Work

Scrap metal shears use hydraulic or mechanical force to drive a blade through metal material. The cutting action is a shearing force rather than an impact or grinding action. Two blades are involved in every cut: an upper moving blade and a lower fixed blade. The metal is placed between the two blades, and the upper blade is driven down, shearing the metal against the lower blade. The clearance between the upper and lower blade determines cut quality. In metal recycling, shears are used to reduce scrap to manageable sizes for further processing, charging into furnaces, or transport. The design of these Metal Cutting Blades allows shears to process scrap efficiently while maintaining the required cutting force and accuracy. 

Guillotine Shear Blades for Scrap Metal

How Guillotine Metal Cutting Blades Shears Work

Scrap metal guillotine shears use long straight blades to cut metal sheets, plates, and structural sections. The upper blade descends in a guided frame, driving through the material against the fixed lower blade. Guillotine shears for scrap metal are designed for higher forces than guillotine cutters in converting or printing, and the blades are correspondingly more robust.

Scrap guillotines are used for cutting plate steel, sheet metal, light structural sections, and metal offcuts to size. They produce a straight, accurate cross-cut across the full width of the blade. They are less suited to irregular or three-dimensional scrap shapes. For flat and uniform materials, Metal Cutting Blades designed for guillotine shears provide the cutting strength needed for repeated processing. 

Guillotine Blade Specification for Scrap

Scrap guillotine blades are heavy, long, and built to absorb extreme forces. Key specifications include:

• Blade length: Matches the cutting width of the machine. Must be the exact length for the machine’s blade holder.
• Blade thickness: Heavier than equivalent blades in other industries. Thickness provides rigidity against deflection under high cutting forces.
• Clearance: Typically set as a percentage of the material thickness being cut. Correct clearance is critical. Too wide produces a ragged shear zone. Too tight increases blade wear dramatically.
• Blade angles: Most scrap guillotine blades have a rake angle on the upper blade, meaning the blade is set at a slight angle to the horizontal. This reduces the instantaneous cutting force by ensuring the cut progresses across the material width rather than simultaneously across the full length.

Blade Materials for Scrap Guillotines

Scrap guillotine blades are subjected to extreme impact and abrasion. The steel must have good hardness for edge retention alongside sufficient toughness to resist fracture under the high forces involved.

• Chrome-moly tool steels: Good combination of hardness and toughness for most scrap cutting applications.
• H13 hot work tool steel: Used where heat generation during cutting is significant. H13 maintains its hardness at elevated temperatures better than cold-work tool steels.
• Carbide-tipped edges: Used in high-volume operations where maximum edge life between changes is valuable. Carbide is brittle, so the tip design must protect the carbide from lateral impact forces.

Alligator Shear Blades for Scrap Metal

How Alligator Shears Work

Alligator shears (also called crocodile shears) use a scissor-like cutting action. One jaw is fixed, and one jaw pivots from a hinge point, driving down to cut the material against the fixed lower jaw. The jaw shape resembles an open-mouthed alligator, which gives the tool its name.

Alligator shears are used for cutting long or irregular scrap pieces to length. They are commonly used at scrap yards, demolition sites, and metal recycling facilities for processing structural steel, rebar, pipes, angles, and sheet metal bundles. They are more portable and versatile than guillotine shears for handling irregular feed. The right Metal Cutting Blades can help alligator shears handle demanding scrap while maintaining a consistent cutting action.

Alligator Shear Blade Design

Alligator shear blades are shorter and more robust than guillotine blades. They need to handle the three-dimensional forces that come from cutting irregular or curved scrap material. The upper jaw blade is typically hardened throughout its length. The lower jaw provides the anvil surface for the cut.

Blade replacement on alligator shears is done one jaw at a time. The blades are bolted into the jaws and can be replaced in the field without specialist equipment. This is a practical advantage in scrap yard environments where maintenance conditions are not ideal.

Blade Materials for Alligator Shears

Alligator shear blades experience similar demands to guillotine blades but with a greater proportion of impact loading from irregular feed. Toughness is prioritized alongside hardness.

• Abrasion-resistant steels (AR400, AR500): Used for the blade bodies in high-abrasion environments.
• Chrome-moly alloy steels: Good for blades that need to absorb shock without fracturing.
• Through-hardened tool steels: Used where a uniform hardness throughout the blade thickness is needed for extended regrinding life.

Key Differences Between Guillotine and Alligator Shear Blades

• Cut type: Guillotine produces a straight cross-cut. Alligator produces a chopping or cross-cut on longer material.
• Feed material: Guillotine suits flat sheet and plate. Alligator handles long, irregular, or three-dimensional scrap.
• Blade length: Guillotine blades are longer to cover the full cutting width. Alligator blades are shorter and more compact.
• Force profile: Guillotine applies force progressively across a long blade. Alligator concentrates force at the cutting point.
• Field serviceability: Alligator blades are simpler to replace in field conditions. Guillotine blades typically require more controlled conditions for correct re-fitting.

When to Regrind or Replace Scrap Shear Blades

Scrap metal shear blades wear through abrasion and impact. The cutting edge becomes rounded, and the clearance between upper and lower blades increases as the blades wear. Regular inspection of Metal Cutting Blades can help identify wear before it begins to affect cutting performance. Signs that blades need attention:

• Visible rounding or chipping of the cutting edge
• Ragged shear zone on cut metal surfaces
• Increased force required for the same material
• Material deflecting or slipping during cutting
• Increased cycle time to complete a cut

Scrap shear blades can be reground and rehardened in many cases. When the blade is worn but not cracked, regrinding restores the edge geometry and re-establishes the correct clearance. When the blade body is cracked or has lost too much material to regrind safely, replacement is required.

Need Scrap Metal Shear Blades for Your Operation?

Edgemills manufactures and supplies Metal Cutting Blades for guillotine shears and alligator shears. Standard and custom sizes in chrome-moly, H13, AR steels, and carbide-tipped. Contact us with your machine specifications.

FAQs