Selecting the Right Shearing Machine Blade: A Guide to Material Grades and Blade Gap Optimization

The shear is the “entry point” of the fabrication shop. If the initial cut is burred, twisted, or bowed, every subsequent process—from CNC punching to bending—will be inaccurate. MIHARTING shearing machine blades are engineered to provide “clean-room” quality cuts by focusing on metallurgical stability and precision edge geometry.

1. Material Science: Selecting the Right Grade

At MIHARTING, we categorize our blades based on the “Application Stress Profile.”

• Cr12MoV (D2 Style): The workhorse for mild steel. High carbon and high chrome content provide excellent wear resistance.

• H13 (Work Tool Steel): Engineered for high-speed, high-heat environments. We recommend H13 for shops shearing heavy-gauge stainless steel (Inox) consistently.

• 6CrW2Si: Used for shock resistance when cutting thicker, uneven plates where “impact” is more of a factor than “abrasion.”

  
  

2. The Science of Blade Gap (Clearance)

A common mistake in many shops is failing to adjust the blade gap when switching material thicknesses.

• The 10% Rule: For mild steel, the gap should generally be 8% to 10% of the material thickness.

• Impact of Improper Gap:

  Too Tight: Results in “double shearing” and massive heat buildup, destroying the blade edge.

  Too Loose: Results in a “heavy burr” and the material being pulled into the gap rather than cut.

3. MIHARTING’s Heat Treatment Process

The “secret sauce” of a MIHARTING shearing machine blade is our four-stage vacuum heat treatment. We don’t just harden the edge; we stabilize the entire body of the blade to HRC 58-62. This prevents the blade from “bowing” under the immense lateral pressure of a guillotine shear.

4. Troubleshooting: Identifying “Edge Fatigue”

Fabricators should inspect their blades for:

• Chipping: Usually caused by cutting material that is too hard or having a gap that is too tight.

• Rounding: Normal wear that indicates it is time for a precision regrind. MIHARTING blades are designed with enough “regrind stock” to allow for 5-8 sharpenings over their lifespan.