· KAIPU Engineering · glossary · 2 min read
Hone (Micro-hone) — Industry Glossary Entry
Definition of hone (also micro-hone or edge radius) in industrial cutting: the small radius at the very tip of a cutting edge, the substrate-by-substrate range, and the relationship to coating thickness and burr.
Hone (also: micro-hone, edge radius, secondary radius) is the small radius formed at the very tip of a cutting edge during the final grinding or stropping operation. The hone absorbs thermal and mechanical shock at the edge, prevents micro-chipping, and — when sized correctly for the substrate — reduces burr.
Units: micrometres (µm) for thin knives (< 5 mm section), millimetres (mm) for thick knives (≥ 5 mm section), typically expressed as the radius of the rounded tip.
Typical ranges by substrate:
| Substrate | Hone | Why |
|---|---|---|
| Paper, light packaging | 5–10 µm | Standard; balances clean cut and edge life |
| Tissue (1,000+ m/min) | 10–15 µm | Thermal shock at high speed demands more hone |
| Film, foil | 5–10 µm | Thin material, low drag |
| Plastic (neat) | 5 µm | Clean cut, low abrasive load |
| Plastic (glass-filled) | 5–10 µm | Abrasive — slightly more hone for chip resistance |
| Stainless steel strip | 5–10 µm | Work-hardening substrate; hone prevents galling |
| Plate shear (carbon steel, ≤ 6 mm) | 0.05–0.10 mm chamfer | Thick section, impact load |
| Plate shear (stainless, ≤ 4 mm) | 0.10–0.15 mm chamfer | Work-hardening, demanding geometry |
| Granulator bed knife | 0.10–0.20 mm chamfer | High impact |
| Granulator rotor knife | 0.20–0.30 mm chamfer | Maximum edge support |
Common mistakes:
- Razor edge on a hot line. A 0–2 µm hone on a 1,200 m/min tissue line fails by thermal fatigue micro-cracking inside 2 weeks. Add 10–15 µm.
- Over-hone on a thin knife. A 30 µm hone on a 1 mm slitter blade will push material rather than cut it. Burr grows.
- Hone lost on re-grind. A re-grind that does not restore the hone to the substrate-appropriate radius is the most-common re-grind error. Always specify the hone in the re-grind SOP.
- Hone smaller than the PVD coating thickness. A 3 µm TiN coating on a 5 µm steel hone creates a negative effective hone (the coating wraps the edge). The steel hone should be ≥ 2× the coating thickness.
- Hone varying around the perimeter. On a circular slitter, the hone should be uniform. A re-grind that left the centre 5 µm different from the edge will cut unevenly.
See also: Clearance angle, Burr, Chipping, PVD Coating Comparison Table, The KAIPU 5-Factor Blade Selection Framework.