DCMT070204: what every position of the code means
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.
Same family, cross-referenced DCMT11T304