The size of indexable inserts is determined by the diameter of an inscribed circle (I.C.), except for rectangular and parallelogram inserts where the length and width dimensions are used. To describe an insert in its entirety, a standard ANSI B212.4-1986 identification system is used where each position number designates a feature of the insert. The ANSI Standard includes items now commonly used and facilitates identification of items not in common use.

Identification consists of up to ten positions; each position defines a characteristic of the insert as shown below:

1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |

T | N | M | G | 5 | 4 | 3 | A |

Eigth, ninth and tenth positions are used only when required

*Shape:*

The shape of an insert is designated by a letter: R for round; S, square; T, triangle; A,
85º parallelogram; B, 82º parallelogram; C, 80º diamond; D, 55º diamond; E, 75º
diamond; H, hexagon; K, 55º parallelogram; L, rectangle; M, 86º diamond; O, octagon; P,
pentagon; V, 35º diamond; and W, 80º trigon.

* Relief Angle (Clearances):*The second position is a letter denoting the relief angles; N for 0º; A,
3º; B, 5º; C, 7º; P, 11º; D, 15º; E, 20º; F, 25º; G, 30º; H, 0º & 11ºß; J,
0º & 14ºß; K, 0º & 17ºß; L, 0º & 20ºß; M, 11º & 14ºß; R, 11º
& 17ºß; S 11º & 20ºß. When mounted on a holder, the actual relief angle may
be different from that on the insert. (ß - Second angle is secondary facet angle,
which may vary by ±1°.)

* Tolerances:*The third position is a letter and indicates the tolerances which control
the indexability of the insert. Tolerances specified do not imply the method of
manufacture.

* Type:*The type of insert is designated by a letter. A, with hole; B, with hole and
countersink; C, with hole and two countersinks; F, chip grooves both surfaces, no hole; G,
same as F but with hole; H, with hole, one countersink, and chip groove on one rake
surface; J, with hole, two countersinks and chip grooves on two rake surfaces; M, with
hole and chip groove on one rake surface; N, without hole; Q, with hole and two
countersinks; R, without hole but with chip groove on one rake surface; T, with hole, one
countersink, and chip groove on one rake face; U, with hole, two countersinks, and chip
grooves on two rake faces; and W, with hole and one countersink. Note: a dash may be used
after position 4 to separate the shape-describing portion from the following dimensional
description of the insert and is not to be considered a position in the standard
description.

* Size:*The size of the insert is designated by a one- or a two-digit number. For
regular polygons and diamonds, it is the number of eighths of an inch in the nominal size
of the inscribed circle, and will be a one- or two-digit number when the number of eighths
is a whole number. It will be a two-digit number, including one decimal place, when it is
not a whole number. Rectangular and parallelogram inserts require two digits: the first
digit indicates the number of eighths of an inch width and the second digit, the number of
quarters of an inch length.

* Thickness:*The thickness is designated by a one- or two-digit number, which indicates
the number of sixteenths of an inch in the thickness of the insert. It is a one-digit
number when the number of sixteenths is a whole number; it is a two-digit number carried
to one decimal place when the number of sixteenths of an inch is not a whole number.

* Cutting Point Configuration:*The cutting point, or nose radius, is designated by a number representing
1/64ths of an inch; a flat at the cutting point or nose, is designated by a letter: 0 for
sharp corner; 1, 1/64 inch radius; 2, 1/32 inch radius; 3, 3/64inch radius; 4, 1/16 inch
radius; 5, 5/64 inch radius; 6, 3/32 inch radius; 7, 7/64 inch radius; 8, 1/8 inch radius;
A, square insert with 45º chamfer; D, square insert with 30º chamfer; E, square insert
with 15º chamfer; F, square insert with 3º chamfer; K, square insert with 30º double
chamfer; L, square insert with 15º double chamfer; M, square insert with 3º double
chamfer; N, truncated triangle insert; and P, flatted corner triangle insert.

* Special Cutting Point Definition:*The eighth position, if it follows a letter in the 7th position, is a number
indicating the number of 1/64ths of an inch measured parallel to the edge of the facet.

* Hand:*R, right; L, left; to be used when required in ninth position.

* Other Conditions:*The tenth position defines special conditions (such as edge treatment,
surface finish) as follows: A, honed, 0.0005 inch to less than 0.003 inch; B, honed, 0.003
inch to less than 0.005 inch; C, honed, 0.005 inch to less than 0.007 inch; J, polished, 4
microinch arithmetic average (AA) on rake surfaces only; T, chamfered, manufacturer's
standard negative land, rake face only.

**Tolerance (± from nominal):**

Symbol |
Inscribed Circle, Inch |
Thickness, Inch |

A | 0.001 | 0.001 |

B | 0.001 | 0.005 |

C | 0.001 | 0.001 |

D | 0.001 | 0.005 |

E | 0.001 | 0.001 |

F | 0.0005 | 0.001 |

G | 0.001 | 0.005 |

H | 0.0005 | 0.001 |

J | 0.002 | 0.001 |

K | 0.002 | 0.001 |

L | 0.002 | 0.001 |

M | 0.002 | 0.005 |

U | 0.005 | 0.005 |

N | 0.002 | 0.001 |

Last modified: 01/10/2005