Carbide Grade Names Explained: How to Read Sandvik, Kennametal, ISCAR, Mitsubishi and Korloy Codes

Early in my time on the floor a job sheet came down for a batch of plain steel shafts — CNMG120408 in Sandvik 4325. The crib had no 4325. What it had was KCP25C, UE6110, NC3225 and IC8150. Same rhombic shape, same 0.8 mm corner, same job in P20 steel — five names with not a single letter visibly in common.

The sheet was right, by the way, and so were the boxes. All five were valid answers. Every grade name in our industry is a compressed sentence — what I cut, how I'm coated, which generation I am — and each manufacturer wrote the sentence in its own dialect. After enough years of pulling the wrong box off the shelf I learned to read all five. This guide is that reading lesson, demonstrated against the 322 grade records from these five brands in the InsertBase catalogue. Every pattern below is something you can check against the linked grade pages; where a maker declares nothing, I say so instead of guessing.

Every grade name answers the same three questions

Before the brands diverge, they agree on what the name has to tell you:

1. The workpiece family. The ISO 513 groups — P for steel, M for stainless, K for cast iron, N for non-ferrous, S for superalloys, H for hardened. Some brands print the letter outright; others hide it in a digit.

2. The coating family. CVD thick-stack armour for hot, continuous cuts, or a thin sharp PVD skin for sticky material and interrupted cuts. If the CVD-versus-PVD decision is new to you, read that guide first — the name often tells you which one you're holding.

3. The position in the range and the generation. Hard and wear-resistant for finishing, or tough for roughing — and whether this is the old formulation or the one the rep is currently pushing.

That's the whole grammar. Now the dialects.

Sandvik: the first digit is the family

Of the 28 all-numeric Sandvik turning grades in our catalogue, the leading digit sorts them almost perfectly. This is the pattern I wish someone had just told me on day one:

Read that table again and it's barely in code at all. The 4000 row is the CVD steel family the whole industry cross-references against. The 1000 row is the PVD sharp-edge family you reach for in stainless and heat-resistant material. The 3000 row belongs to cast iron. Two older grades in our catalogue still carry the legacy GC prefix (GC15, GC30); the modern turning line is the numbers, and a stray S205 sits in the S-group slot you'd predict.

Kennametal: the letters tell you the material, the suffix tells you the generation

Kennametal runs the most literal system of the five. The modern steel grades are KC + group letter + position — and the group letter is exactly the ISO group the grade is filed under in the catalogue:

Once you know this, the shelf reads itself. KCM is the stainless row, KCK is the cast iron row, KCU is the one box that's supposed to survive anything. The 46 grades on the older plain KC-numbered scheme (KC5010, KC5025 and friends — no third letter) predate the lettered system and span the steel, stainless, iron, non-ferrous and superalloy groups, stopping short of hardened H. That breadth is exactly why older machinists still order them from memory and nobody else can find anything. The catalogue isn't uniformly deep past the carbide rows, either, and I won't paper over that: the KBH grades at least declare themselves in plain words — KBH10B and KBH20B are catalogued as PVD coated PcBN for hardened steel and file under H, and KYS30 is filed as a SiAlON ceramic grade for high-temp alloys in S. But the twelve KY-numbered and nine KB-numbered grades carry no coating declaration and, for most of them, no ISO group in the records we pull, so I won't invent jobs for them — that's what the box label and the maker's current PDF are for. One honesty note on the main rows: Kennametal doesn't declare the coating stack in the feed we pull, so unlike the other brands I can't show you their CVD/PVD split from catalogue data. The naming does the work instead.

The suffix is where I've watched people actually lose money. The catalogue contains 16 base-and-B pairs — KCP05 and KCP05B, KCK20 and KCK20B, KCM25 and KCM25B — and then the current steel flagship, KCP25C, sits one generation further on. Same family position, three iterations. The B and C generations are reformulated, not interchangeable rebrands. A job sheet written against KCP25 in 2014 is talking about a grade that has been revised twice. When a distributor says "KCP25 — it's all the same thing," open the box and read the last character yourself. I've been the guy who didn't.

Mitsubishi: the second letter is the workpiece group

Mitsubishi's CVD line is the cleanest pattern in this whole comparison. The U-series grades name the ISO group with the second letter, and across the 11 we catalogue, 11 of 11 are declared CVD:

UE for steel, UC for iron, US for stainless. It's almost suspiciously tidy, and I've used it on supplier websites where the search box only matches the exact code — guessing US for a stainless job gets you into the right family before you've even opened the PDF. The newer MC series (MC5105, MC6125) has taken over much of this range in their current catalogue; the records we pull don't declare its coating, so I treat MC as the successor generation, not as a data point I'll make claims about. The PVD side is the VP line — VP15TF is declared "PVD AlTiN general turning for steel and stainless" — and the NX line is cermet: NX2525's own record says "coated cermet for steel finishing," which is the fine-finishing, low-rake, pretty-surface box you'll hear old hands swear by.

Korloy: NC is the CVD line, PC is the PVD line

Korloy makes the coating family the first thing in the name. Of the 16 grades on the plain NC prefix in our catalogue — the two NCM325/NCM335 codes carry their own separate prefix, so I keep them out of the count — 14 are declared CVD; of the 11 PC-series grades, 8 are declared PVD. That alone gets you to the right shelf:

• NC3xxx — CVD steel generalists: NC3225 is filed "steel P15–P20 general," and NC5330 spans the heavy P35 end into M, K and S.
• NC9xxx — the CVD stainless row: NC9115 is filed "stainless M finishing," and it's the Korloy name that shows up in cross-reference lists against Sandvik 2025.
• PC — the PVD family for stainless, superalloys and hardened steel: PC8110 is filed M10–M20, S05–S15 and H05–H10, with a TiAlN stack on record.

The N versus P first letter is doing real work: in practice it tracks the thick hot-process coating against the thin cool-process one. It pairs naturally with the coating guide's rule of thumb — hot continuous steel cuts toward NC, sticky and interrupted work toward PC.

ISCAR: one prefix, and the number does the talking

ISCAR is the brand that teaches you not to expect a workpiece letter. Every one of the 31 ISCAR grades we catalogue starts with IC. Instead, the shape of the number — and the catalogue description — tells you the generation and the job:

The short numbers are the uncoated fine-grain generation, and five of the six are aluminium grades outright — IC4's own description is "high-speed machining of aluminium, high-silicon aluminium and other non-ferrous metals," IC10 says much the same, and IC20 is filed uncoated for aluminium in N. The exception is worth knowing: IC20N is the same uncoated generation filed instead for semi-finishing steel and alloy steel at high speed. Even a pattern this clean has one member that breaks it — read the card. The three-digit 800/900 row is the PVD workhorse family. The four-digit grades are the modern coated generation, and the descriptions do the rest of the sorting: IC8150 is a CVD TiCN+Al₂O₃+TiN steel-and-iron grade; IC9250 is the cobalt-enriched CVD generalist for steel "under a wide range of conditions." You can't decode an IC grade by syntax alone, and nobody on the shop floor pretends to — you learn the handful your shop runs and look the rest up.

The number language everyone quietly shares

Here's the observation that made the whole mess click for me. Look at the middle of each steel family: Sandvik 4305, 4315, 4325, 4335 — Kennametal KCP05, KCP10, KCP15, KCP25, KCP30, KCP40 — Mitsubishi UE6005, UE6020, UE6035. Three different dialects, same counting language. The two-digit position walks from 05 up toward 35 or 40, and in every maker's own catalogue that walk is the same axis: hard and wear-resistant at the low end for light finishing cuts, progressively tougher at the high end for heavier, nastier roughing work.

That's why cross-reference lists are so often number-matched — 4325 to KCP25 to UE6020/UE6110 isn't coincidence, it's three catalogues occupying the same seat at the same table. The shared physics is older than the brand names.

"Equivalent" is a dangerous word

Which brings me to the sentence that has cost more scrapped inserts than any dull tool: they're equivalent grades, it'll be fine.

InsertBase carries 191 catalogue-cited cross-brand grade mappings. Not one is marked exact. 141 are PARTIAL — overlapping application band and coating family, confirmed against an aftermarket chart — and 50 are VERIFY, cross-listed somewhere but not confirmed in both manufacturers' official catalogues. That's not caution for its own sake. Look at the steel P20 row around Sandvik 4325, ten catalogued partners deep:

Five answers to the same job, and the footnotes differ on every row — one extends to cast iron, one's flagged "verify," one sits at P15–P20 instead of P20–P35. The stainless row tells the same story around Sandvik 2025: ISCAR IC6015, Mitsubishi US7020, Kennametal KCM25, Korloy NC9115 — close neighbours, not twins. Different layer stacks, different edge prep, different generations. A mapping gets you to the right neighbourhood. The first cut tells you if you picked the right house.

How I work a grade name I don't know

1. Find the workpiece signal first. A digit (Sandvik 4xxx), a letter (KCM, UE/UC/US), or a coating-family split (Korloy NC/PC). Wrong group, nothing else matters — a K-grade in austenitic stainless will teach you this loudly.

2. Find the coating signal. CVD for hot continuous steel and iron; PVD for stainless, superalloys, hard material and interruptions. If the name hides it, read the description instead of assuming.

3. Read the position number honestly. 05–15 means the maker designed for light cuts and high speed; 25–40 means heavier cuts, more shock, more margin. Match it to your real depth of cut and the machine's condition — not the job you wish you were running.

4. Treat the suffix as a generation. B, C, T, F — they mean the formulation moved. Don't let anyone substitute across a suffix without telling you.

5. Verify the cross against real offers before you buy. Decode the geometry with the ISO 1832 decoder, check the catalogued neighbours with the cross-reference finder — it shows the PARTIAL/VERIFY distinction rather than hiding it — and confirm the grade is actually offered on your geometry on the model page.

The short version: the names only look random. Sandvik put the family in the first digit, Kennametal put the ISO letter in the prefix and the generation on the suffix, Mitsubishi named the group with its second letter, Korloy put the coating family first, and ISCAR made you learn the numbers and read the sentence underneath. They all count toughness from 05 up to 40, and none of them make a grade that is truly "equivalent" to anyone else's. The name gets you to the right shelf. The cut decides the rest.