Single Point Cutting Tool: Nomenclature and Tool Signature

The elements of the tool signature or nomenclature of a single-point cutting tool are illustrated in the figure below

(i) Back rake angle:
Back rake angle is the angle between the face of the single-point cutting tool and a line parallel to the base of the tool, measured in a perpendicular plane through the side cutting edge. If the slope face is downward toward the nose, it is a negative back rake angle and if it is upward toward the nose, it is a positive back rake angle. Back rake angle helps in removing the chips away from the workpiece.

(ii) Side rake angle:
Side rake angle is the angle by which the face of tool is inclined sideways. Side rake angle is the angle between the surface the flank immediately below the point and the line down from the point perpendicular to the base. Side rake angle of a cutting tool determines the thickness of the tool behind the cutting edge. It is provided on the tool to provide clearance between the workpiece and the tool so as to prevent the rubbing of the workpiece with the end flank of the tool.

Schematic illustration of single point cutting tool

(iii) End relief angle:
End relief angle is defined as the angle between the portion of the end flank immediately below the cutting edge and a line perpendicular to the tool's base, measured at right angles to the flank. The end relief angle allows the tool to cut without rubbing on the workpiece.

(iv) Side relief angle:
Side relief angle is the angle between the portion of the side flank immediately below the side edge and a line perpendicular to the base of the tool, measured at right angles to the side. Side relief angle is the angle that prevents interference as the tool enters the material. It is incorporated on the tool to provide relief between its flank and the workpiece surface.

(v) End cutting edge angle:
End cutting edge angle is the angle between the end cutting edge and a line perpendicular to the shank of the tool. It provides clearance between the tool cutting edge and the workpiece.

(vi) Side cutting edge angle:
Side cutting edge angle is the angle between the straight cutting edge on the side of the tool and the side of the shank. It is responsible for turning the chip away from the finished surface.

Tool Signature of Single Point Cutting Tool:

A convenient way to specify tool angles by use of a standardized abbreviated system is known as tool signature. It indicates the angles that a tool utilizes during the cut. It specifies the active angles of the tool normal to the cutting edge. This will always be true as long as the tool shank is mounted at right angles to the workpiece axis.

Elements of tool signature

The seven elements that comprise the signature of a single-point cutting tool are always stated in the following order:

1. Back rake angle (0°)
2. Side rake angle (7°)
3. End relief angle (6°)
4. Side relief angle (8°)
5. End cutting edge angle (15°)
6. Side cutting edge angle (16°) and
7. Nose radius (0.8 mm)

It is usual to omit the symbols for degrees and mm, simply listing the numerical value of each component in a single point-cutting tool:

A typical tool signature is 0-7-6-8-15-16-0.8