Carbide grade quiz.

Six questions

Answer from what you can observe. Skipped questions just make the suggestion less certain.

What the families mean

The quiz suggests one of three grade families. Straight WC-Co (ISO K, ANSI C1–C4, red-coded) is tungsten carbide in a cobalt binder with no titanium or tantalum additives — the cleanest, most tungsten-rich family, and the most straightforward to recycle. Alloyed steel-cutting (ISO P, ANSI C5–C8, blue-coded) adds titanium carbide and tantalum carbide to handle steel; the additives change the recycling chemistry, so keep these grouped apart from straight grades. Stainless grades (ISO M, yellow-coded) may carry nickel or tantalum and sit in their own lane. A fourth result — cannot tell — is the quiz being honest: worn markings, mixed lots, and look-alikes genuinely defeat description-based identification, and long white spark bursts actually point at high-speed steel rather than carbide. Whatever the result, treat it as a starting hypothesis, not a verdict. Photograph the markings and the material, and let an experienced review confirm it — that confirmation is free, and it is what your quote is built on.

Codes you will actually see

A few patterns cover most of what shops encounter. Insert shape codes like CNMG, WNMG, DNMG, and CCMT describe the insert's geometry (shape, clearance, tolerance, chipbreaker) — useful for identifying the tool, though the grade letter stamped alongside them is what matters for recycling. A "K20" or "C2" points at straight WC-Co for cast iron and non-ferrous; a "P20" or "C6" points at alloyed steel-cutting grades; an "M" code points at stainless. Coated grades often carry a "CC" prefix in the ANSI system. Colors help at a glance: blue packaging or markings lean steel-cutting, yellow leans stainless, red leans cast iron and non-ferrous — but treat colors as hints and etched codes as evidence. When the etching has worn off (common on well-used tooling), the quiz's physical questions — magnet, heft, spark — take over, because the material itself never forgets what it is even when the label is gone.

When description-based ID hits its wall

The quiz is upfront about where it stops. Mixed lots defeat it: a bucket containing K-grade inserts, P-grade end mills, and a few HSS strays has no single grade family, and the only correct answer is "sort first, then ask." Worn tooling defeats it: decades of cutting erase laser etching, and while the physical tests still work, certainty drops. Counterfeits defeat it on purpose: coated-steel fakes are engineered to pass visual inspection, and only the density test — about 8 g/cm³ for the fake versus 14–15 for the real thing — reliably exposes them. And some distinctions genuinely need a lab: close grades within the same family, or exact cobalt content, are assay questions, not quiz questions. None of this makes the quiz useless — it tells you which family you are probably in and, just as valuably, when you should stop guessing. The resolution is always the same: clear photos of markings and material, something for scale, and an experienced review. That review is free, and it is what every serious offer is built on.

Carbide questions, answered.