Materials Glossary
"Tungsten carbide" is not one material — it's a family. A "grade" is a specific recipe within that family: a chosen WC grain size, a chosen cobalt binder content, and often a specific coating, all tuned together for one kind of job. Two inserts can both be tungsten carbide and still behave completely differently in the cut because they're different grades.
Cemented tungsten carbide is a composite — WC grains bound by cobalt — and manufacturers can dial in that composite in a lot of different ways. A "grade" is the specific combination of WC grain size, cobalt content, and (usually) coating that a manufacturer settles on for a target application. Change any one of those three levers and you get a different grade, even if the base material is still "tungsten carbide." That's why a catalog might list dozens of grades built from the same two raw ingredients.
Finer WC grains generally push hardness and wear resistance up; coarser grains push toughness up. Submicron and ultrafine grain grades are used where edge sharpness and wear resistance matter most; coarser-grain grades are chosen where the tool needs to absorb shock without chipping.
More cobalt binder makes the composite tougher and more resistant to chipping, but softer and less wear-resistant. Less cobalt does the opposite. Grades aimed at continuous, stable cuts typically run leaner on cobalt; grades built for interrupted or heavy roughing cuts typically run richer.
A coating adds a hard, wear-resistant, low-friction skin over the substrate without changing the substrate's underlying toughness — see our Coating and CVD & PVD pages for how and why that layer is applied.
To keep all of this navigable, the industry organizes grades using ISO 513, the international standard for classifying hard cutting materials by the type of workpiece they're designed to machine. It sorts materials into six color-coded groups: P (blue) for steel, M (yellow) for stainless steel, K (red) for cast iron, N (green) for non-ferrous metals like aluminum, S (brown) for heat-resistant superalloys and titanium, and H (grey) for hardened materials. Every major manufacturer's grade chart is organized around these six groups, sometimes with a numeric suffix indicating where a grade falls on the hardness-to-toughness scale within its group. It's the fastest way to narrow a catalog of dozens of grades down to the handful actually built for your workpiece.
In practice, picking a grade starts with the ISO letter that matches your workpiece, then narrows further by operation: a hard, wear-resistant grade for stable, continuous cuts; a tougher, more shock-resistant grade for interrupted cuts or heavy roughing. From there, coating and post-treatment fine-tune performance for the specific speed, feed, and finish the job requires.
Matching the ISO letter on the chart to your workpiece is the fastest way to land in the right neighborhood of grades before narrowing by operation.
Shop Carbide Inserts