Cutting tool materials trade toughness for hardness and heat resistance. Tougher materials survive interrupted cuts; harder ones run faster and last longer in clean cuts. The speeds below are rough multiples relative to plain HSS.
| Tool material | Relative speed | Best for |
|---|---|---|
| HSS | 1× (baseline) | General work, taps and drills, interrupted cuts |
| Cobalt HSS (M42) | ~1.5× | Tougher materials; better heat resistance than HSS |
| Uncoated carbide | 3–4× | Most milling and turning |
| Coated carbide | 4–6× | Production work in steel and stainless |
| Ceramic | 8–10× | Hard turning and cast iron at high speed |
| CBN | 10×+ | Hardened steel above ~45 HRC |
| Diamond (PCD) | 10×+ | Abrasive non-ferrous and composites — never steel |
Relative figures — real tool life depends on material, coating, coolant, and rigidity. As a rule, the harder the tool, the faster it runs but the more it dislikes shock and interruption.
FAQ
Is tool life the only factor in choosing between tool types? No. Cost per edge, achievable surface finish, and cycle time from allowable speeds and feeds all factor into total cost per part, so a tool with shorter life but much faster cutting can still be the more economical choice.
Pair this with the Tool Coating Comparison and Feeds and Speeds Chart.