Broach Re-Sharpening: When and Why

1. Why Re-Sharpening Matters

Every broach loses cutting efficiency over time due to friction, heat, and micro-abrasion. Regular re-sharpening ensures the tool maintains its designed geometry and continues to produce accurate components. Ignoring dullness leads to higher cutting forces, chatter, and poor surface finish — eventually damaging the broach beyond repair.

2. Signs Your Broach Needs Re-Grinding

• Increase in machine load or vibration during stroke.
• Visible wear land or chipping on cutting teeth.
• Loss of tolerance or burrs on the finished workpiece.
• Surface roughness above specification (Ra > 1.6 µm typical alert level).

3. When to Re-Sharpen — Preventive Intervals

Broach re-sharpening intervals depend on the material and production volume: mild steel 4 000 – 6 000 strokes, alloy steels 2 000 – 3 000, cast iron 1 500 – 2 000. Keeping a usage log helps plan service before catastrophic wear occurs.

4. The CNC Re-Sharpening Process

Modern re-sharpening is performed on CNC profile grinders equipped with CBN or diamond wheels. Steps include:

• Mounting and referencing of broach profile.
• Precision grinding of rake and relief surfaces within ±2 µm accuracy.
• Profile verification via CMM or optical comparator.
• Optional coating removal and re-coating (TiN, TiAlN, AlCrN).

Controlled coolant flow prevents thermal distortion, ensuring repeatable results.

5. Geometry Control and Tooth Count

Every re-grind slightly reduces tool length; after several cycles, the broach may require shortening and adjustment of pull end. Keeping a record of total stock removal and remaining life prevents over-grinding and ensures correct staging for the next production run.

6. Re-Coating After Re-Sharpening

After re-grinding, apply a new PVD coating to restore wear protection. TiN provides good all-purpose performance; TiAlN is ideal for dry or high-temperature operations. Ensure surfaces are properly cleaned and pre-heated to maximize adhesion.

7. Inspection and Documentation

Final inspection includes checking major/minor diameters, tooth form, and pitch using gauges or CMM. A re-sharpening report documenting stock removal and coating details should accompany every returned tool.

Broş Takım Sanayi offers professional CNC re-sharpening, re-coating, and geometry restoration up to 1600 mm length. Contact our service team for quotation or technical support.