Lathe - Single Point Cutting Tool
Symbol used in figure are :
- αb – Back rake angle
- αs – Side rake angle
- θe – End relief angle
- θs – Side relief angle
- Ce – End cutting edge angle
- Cs – Side cutting edge angle
Size :It is determined by the width of shank, height of shank and overall length.
Shank : Shank is main body of a tool. It is held in a holder.
Flank : Flank is the surface or surfaces below and adjacent to cutting edge.
Heel : Heel is intersection of the flank and base of the tool.
Base : Base is the bottom part of the shank. It takes the tangential force of cutting.
Face : Face is surface of tool on which chip impinges when separated from workpiece.
Cutting Edge : Cutting edge is the edge of that face which separates chip from the workpiece. The
total cutting edge consists of side cutting edge, the nose and end cutting edge.
Tool Point : That part of tool, which is shaped to produce the cutting edge and the face.
The Nose : It is the intersection of side cutting edge and end cutting edge.
Neck : Neck is the small cross section behind the point.
Side Cutting Edge Angle : The angle between side cutting edge and side of the tool shank is called side
cutting edge angle. It is also called as lead angle or principle cutting angle.
End Cutting Edge Angle : The angle between the end cutting edge and a line perpendicular to the shank of
tool is called end cutting edge angle.
Side Relief Angle : The angle between the portion of the side flank immediately below the side cutting
edge and line perpendicular to the base of tool measured at right angles to the side
flank is known as side relief angle. It is the angle that prevents interference, as the
tool enters the work material.
End Relief Angle : End relief angle is the angle between the portion of the end flank immediately
below the end cutting edge and the line perpendicular to the base of tool, measured
at right angles to end flank. It is the angle that allows the tool to cut without
rubbing on the workpiece.
Back Rake Angle : The angle between face of the tool and a line parallel with the base of the tool,
measured in a perpendicular plane through the side cutting edge is called back rake
angle. It is the angle which measures the slope of the face of the tool from the nose
toward the rear. If the slope is downward toward the nose, it is negative back rake
angle. And if the slope is downward from the nose, it is positive back rake angle. If
there is not any slope, back rake angle is zero.
Side Rake Angle : The angle between the face of the tool and a line parallel with the base of the tool,
measured in a plane perpendicular to the base and side cutting edge is called side
rake angle. It is the angle that measures the slope of the tool face from cutting
edge. If the slope is towards the cutting edge, it is negative side rake angle. If the
slope is away from the cutting edge, it is positive side rake angle.
All the tool angles are taken with reference to the cutting edge and are, therefore,
normal to the cutting edge. A convenient way to specify tool angle is by use of a
standardized abbreviated system called tool signature. Sometimes it is also called
as tool character. Tool signature also describes how the tool is positioned in
relation to the workpiece.
The signature for single point tool is listed in the order as rake angles (back and side),
relief angles (end and side), cutting edge angles (end and side) and nose radius.