General turning inserts come in variety of shapes and sizes. One thing is important to remember and understand is that every turning insert has a nomenclature associated with it. These general turning inserts nomenclature tells us lot about these general turning inserts.

The turning inserts nomenclature is a list of some letters and numbers, but lot more data is hidden inside them.

**Note: The following explanations are according to metric inserts.**

The above turning insert nomenclature is **CNMG 120408**.

Contents

**1 = Turning Insert Shape**

The first letter in general turning insert nomenclature tells us about the general turning insert shape, turning inserts shape codes are like C, D, K, R, S, T, V, W. Most of these codes surely express the turning insert shape like

- C = C Shape Turning Insert
- D = D Shape Turning Insert
- K = K Shape Turning Insert
- R = Round Turning Insert
- S = Square Turning Insert
- T = Triangle Turning Insert
- V = V Shape Turning Insert
- W = W Shape Turning Insert

## 2 = Turning Insert Clearance Angle

- B = Turning Insert with 5° clearance angle
- C = Turning Insert with 7° clearance angle
- E = Turning Insert with 20° clearance angle
- N = Turning Insert with 0° clearance angle
- P= Turning Insert with 11° clearance angle

**poor machining**.

## 3 = Turning Insert Tolerances

The third letter of general turning insert nomenclature tells us about the turning insert tolerances.

These are the turning insert tolerances in different insert sizes, like the tolerance in turning insert length, height etc. I personally think that they are not of any use for a cnc machinist, because theses tolerances are minor.

## 4 = Turning Insert Type

The fourth letter of general turning insert nomenclature tells us about the turning insert hole shape and chip breaker type.

- A = Turning insert with Cylindrical hole
- G = Turning insert with Cylindrical hole and Double-Sided Chipbreaker
- M = Turning insert with Cylindrical hole and Single-Sided Chipbreaker
- N = Turning insert with no hole and no Chipbreaker
- P = Turning insert with Cylindrical hole and Hi-Double-Positive Chipbreaker
- Q = Turning insert with 40-60° Double Countersink Hole
- R = Turning insert with no-hole and Single-Sided Chipbreaker
- T = Turning insert with 40-60° Double Countersink Single-sided Chipbreaker
- W = Turning insert with 40-60° double countersink
- X = Turning insert with Special Design

## 5 = Turning Insert Size

This numeric value of general turning insert tells us the cutting edge length of the turning insert.

## 6 = Turning Insert Thickness

This numeric value of general turning insert tells us about the thickness of the turning insert.

## 7 = Turning Insert Nose Radius

This numeric value of general turning insert tells us about the nose radius of the turning insert.

**Code = Radius Value**- 04 = 0.4
- 08 = 0.8
- 12 = 1.2
- 16 = 1.6

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