What does DCMT070204 mean? Every position of the ISO 1832 code, decoded
DCMT070204 is not a part number, it is a sentence. Four letters describe the insert — shape, clearance, tolerance, fixing and chipbreaker — and the number block 070204 gives its size, thickness and nose radius. Decoded below, position by position.
- D — shape
- 55° rhombic (diamond) · a profiling shape: more side clearance than an 80° diamond, so it reaches into contours a C cannot
- C — clearance angle
- relief angle 7°
- M — tolerance
- class M — molded, medium tolerance on inscribed circle and corner point (typically ±0.05–0.13 mm depending on size)
- T — type
- fixing hole with countersink, chipbreaker on one face (single-sided positive insert)
- 07 — size
- size class 7 — nominal cutting-edge length class in mm; the exact edge length and inscribed circle depend on the shape, see a catalog drawing
- 02 — thickness
- insert thickness 2.38 mm
- 04 — corner radius
- Rε = 0.4 mm nose radius
| Shape | 55° rhombic (diamond) |
| Insert style | Positive, single-sided |
| Usable edges | 2 (typical, 2 corners × 1 face) |
| Thickness | 2.38 mm |
| Nose radius | 0.4 mm |
| Size class | 7 (nominal cutting-edge length class, mm — exact dimensions depend on shape) |
Negative or positive — what position 2 commits you to
The C in position 2 means 7° of built-in clearance: a positive, single-sided insert with 2 usable corners. Positive inserts cut with lower forces — kinder to thin walls, small machines, boring bars and gummy materials — at the price of half the edges of a double-sided negative.
The 0.4 mm nose radius in practice
The final 04 is the nose radius in hundredths of a millimetre: 0.4 mm — a finishing-side radius: low radial force, good for slender parts and fine profiles, at the cost of a weaker corner. Surface roughness scales with feed² over radius, so radius choice sets your feed ceiling for a given finish.
One honest caveat: this page decodes the geometry. Which carbide grade, coating and chipbreaker to run on it is a separate decision that depends on your material and cut — the code alone cannot answer it. Dimensions here are nominal ISO classes; verify exact edge length against a maker's catalog drawing.
Frequently asked questions
What does DCMT070204 mean on a turning insert?
DCMT070204 is an ISO 1832 designation. D = 55° rhombic (diamond) shape. C = 7° clearance. M = tolerance class M. T = fixing hole with countersink, chipbreaker on one face (single-sided positive insert). 07 = size class 7 (nominal cutting-edge length class in mm; exact dimensions depend on the shape). 02 = 2.38 mm thickness. 04 = 0.4 mm nose radius.
Is DCMT070204 a positive or negative insert?
Positive. Position 2 is C, i.e. 7° of built-in clearance, so it is single-sided with 2 usable corners. Lower cutting forces than a negative insert.
What do the numbers 070204 mean on DCMT070204?
Three pairs: 07 is the size class (nominal cutting-edge length class in mm), 02 is the thickness (2.38 mm), and 04 is the nose radius (0.4 mm). Exact edge length and inscribed circle depend on the shape — verify against a maker's catalog drawing.
What is DCMT070204 in ANSI (inch) designation?
DCMT 21.51. US catalogs use the ANSI B212.4 inch system: the size digit is the inscribed circle in eighths of an inch, the thickness digit is sixteenths, the radius digit is sixty-fourths. DCMT070204 and DCMT 21.51 describe the same insert geometry in two systems.
Same family, cross-referenced DCMT11T304
| DCMT070204 (ISO 1832) | = DCMT 21.51 (ANSI B212.4) |
| Same insert geometry, two designation systems: the ANSI size digit is the inscribed circle in eighths of an inch, thickness in sixteenths, nose radius in sixty-fourths. US catalogs and forums use the inch code. | |
Are you overpaying on your DCMT070204 inserts? Paste your insert list and get a cost audit in about 30 seconds: cross-brand equivalents at the same ISO application position, and where you are likely overpaying. No signup, no sales call.