Chipping — Industry Glossary Entry

Chipping is the loss of small fragments of material from the cutting edge of an industrial blade. Chipping is distinct from wear (which is a gradual loss of edge material) and from gross fracture (which is a catastrophic break of the whole knife). Chipping is the failure mode that turns a “worn-out” knife into a “scrap” knife.

Visual tells: Visible fragments missing from the edge, typically 0.1–2 mm in size. May be accompanied by a wire-edge or rolled edge. Burr grows on the chipped side. Cut surface shows scratches or tears downstream of the chip.

The four root causes:

1. Edge hone too sharp. A 0–2 µm hone on a substrate that demands 5–15 µm will fail by micro-chipping within hours.
2. Hardness too high. HRC 64 on a 1.5 mm section, on a substrate that allows HRC 60, will chip. Hardness is a wear-vs-toughness trade; a 4-point drop buys 30–50 % more chip resistance.
3. Impact load. Granulator rotors, swing-beam shears with misaligned stock, crusher blades. A D2 or HSS knife on a high-impact line should be HRC 58–60, not HRC 62–64.
4. Heat-treat defect. Decarburisation leaves a soft surface. The hard substrate beneath cracks the soft skin on impact. A 5-point file test catches it.

By substrate, the chipping tendency:

• Paper, tissue: low (low impact, low hardness demand)
• Film, foil: low–medium (thin section, sharp edge)
• Plastic (neat): low
• Plastic (glass-filled): medium (abrasive, some impact)
• Stainless plate: high (work-hardening, demands hard knife)
• Corrugated: medium (abrasive, occasional metal)
• Recycled polymer: high (contamination, impact)
• Food / meat-bone: high (impact, contamination)

Fixes, in order of cost:

1. Add hone (0.05–0.10 mm chamfer or 10–15 µm micro-hone). Cheapest fix.
2. Drop hardness 2–4 HRC points. Drops wear life 10–20 % but doubles chip resistance.
3. Move to a tougher steel grade (D2 → M2 HSS, M2 → M42, YG6X → YG8).
4. Audit heat-treat (5-point file test, mill certificate, decarb-free guarantee).
5. Fix the upstream problem (substrate contamination, line alignment, knife clamp).

See also.