The substrate: is the bare material of the cutting insert or solid tool underneath the coatings and post-treatments. It is typically made up of between 80- and 95-percent WC (WC referred to as Wolfram, and it’s a combination of tungsten (W) and carbon (C) refactored together. To give the substrate the desired properties, material manufacturers add various alloying elements. The main alloying element is 5-15% cobalt (Co) — higher levels of cobalt lead to greater toughness, while lower levels of cobalt lead to greater hardness.
The primary property of interest to the machinist is the hardness of the substrate.
They can operate only at lower cutting speeds, will wear out faster, but have much better resistance to interrupted cuts and unfavorable conditions.
The right balance between hardness and toughness is critical for achieving a longer tool-life and higher productivity in each application.
| MATERIALS | TURNING AND GROOVING | MILLING | ||
|---|---|---|---|---|
| Continues | Light Interrupted | Heavy Interrupted | ||
| P | Hard | Medium | Tough | Tough |
| M | Hard | Medium | Tough | Tough |
| K | Hard | Medium-Hard | Medium | Medium |
| N | Hard | Medium-Hard | Medium | Tough |
| S | Hard | Medium-Hard | Tough | Medium |