A Catalogue Census: What 367 Insert Models Actually Contain

Every tooling catalogue I have ever used felt bottomless: page after page of variations, each with a reason to exist. When we finished collecting the first five brands into InsertBase, I expected the same shape — a handful of workhorse inserts carrying most of the rows, then a long tail of odd sizes.

Then I counted. 367 ISO 1832 models, 19,449 cited ordering codes, five brands. The distribution is not a smooth power law. It is lumpy in ways that matter at the counter, and the lumps explain a question we get constantly: why can this insert be cross-referenced five ways while that one has no equivalent at all?

This is a census of what is actually in the library on 3 November 2026 — Kennametal, Sandvik, Korloy, Mitsubishi and ISCAR. It is a census of collected catalogue data, not of the market. Every number below can be re-run from the model index.

Two circle sizes carry two thirds of the catalogue

Of the 367 models, 250 sit at 9.525 mm or 12.7 mm — 68% of the library in two rows of the size table. Everything else, from 4.76 mm to 25.4 mm, shares the remaining third.

The practical reading: if you work in general turning, most of what crosses your bench will be a 3/8 or 1/2 insert. If you work in boring bars or small-part turning, most of the catalogue is irrelevant to you, and the 6.35 mm group — 52 models — is where your search should start.

3/16 inch is the default thickness

156 models use the 4.76 mm (3/16 in) thickness — 42.5% of the catalogue. No other thickness comes close, and the gap between 4.76 and the next group is larger than the gap between the next four groups combined.

This is where a common substitution error lives. Two inserts can share the exact same shape and circle and still not fit the same pocket because the thickness is one size apart — and the pocket depth, clamp and chipbreaker clearance all change with it. When a cross reference fails despite matching letters and size digits, check s before doubting the source.

The corner radius splits almost evenly

102 models at 0.4 mm and 102 at 0.8 mm — exactly even at the top, with 1.2 mm and 0.2 mm behind. Half the catalogue is a finishing or general-purpose corner; the other half is everything else.

The role column is a starting point, not a rule — the nose radius guide covers the feed and depth-of-cut interaction. What the census shows is that the two radii most shops keep on the shelf are the two most catalogued, which is why R0.4 and R0.8 substitutes are easy to find and R0.2 or R2.4 substitutes are not.

Three shapes carry 61% of the models

Triangle (T), square (S) and 80° rhombic (C) account for 223 of 367 models. Add the 55° rhombic (D) and you are at 77%. The trigon (W) and the round (R) are minority geometries in this set — 24 and 6 models.

Shape is the one axis where a cross reference cannot rescue you. A T and a C can share a circle and thickness and still need different holders, different approach angles, different depths. That is why the shape guide exists separately from the size tables.

Negative edges are just over half

193 models are negative (N clearance, 0°) and 174 are positive — a 53/47 split. If your mental model is "most inserts are negative", the catalogue agrees, but only barely. The positive half is where the small-diameter, low-rigidity and finishing work sits, and it is larger than most people expect.

The split also explains a difference in naming: positive inserts carry the thickness letter in ISO codes (CCMT09T304) while negative ones do not (CNMG120408). If a code seems to have an extra letter, check the clearance first.

Depth is uneven: median 15 rows, 128 single-brand models

This is the part that surprised me most. The mean is pulled up by a few giants, but the typical model is thin:

• Median: 15 cited ordering codes per model
• Interquartile range: 3 to 40 rows
• 155 models (42%) have fewer than 10 cited rows
• 31 models have 200 or more
• The top five models carry 14.3% of all 19,449 rows — CNMG120408 alone has 680

And 128 of 367 models (35%) are single-brand: only one of the five manufacturers catalogues that geometry. That is the direct answer to "why is there no cross reference for this insert?" — there is nothing to cross to. The tool says so rather than inventing an equivalent.

Two more coverage facts fall out of the same count: 314 of 367 models carry an ANSI code (18,722 of 19,449 rows, 96.3%), and the 53 ISO-only models are concentrated in catalogues that publish no ANSI field. The ANSI conversion guide has the mapping table and the suffix trap.

What this means at the counter

• Start from the size group, not the brand. If the job needs a 12.7 mm corner, the 12.7 mm group is the shortest path to every shape and thickness that actually exists.
• Expect cross references to thin out as you leave 9.525/12.7. 68% of the catalogue lives there; the small and large sizes are where single-brand models cluster.
• Treat a one-brand model as a stop sign, not a puzzle. It means no cited equivalent exists yet, not that someone forgot to list one.
• Check thickness and corner before celebrating a match. Same letters and same size digits with a different s or rε is a different insert.

One caveat belongs on every number here: this is the collected catalogue, not the global market. Five brands, 19,449 rows, and a deliberate bias toward the designations that appear in published ordering tables. When more brands and rows are added, the percentages will move. The editorial policy explains how rows are sourced and corrected, and every model page shows its own cited count so you can check the census one insert at a time.