Shank
The shank is that portion of the tool bit which is not ground to form cutting edges and is rectangular in cross section. It is the body part of the tool for holding in machine.
Face
It is the surface of the tool over which the chip flow
Flank
It is the end surface of the tool which face the workpiece
Heel
It is the lowest portion of end flank and side flank
Nose
It is the small radius made on the cutting edge to improve the surface finish.
Base
Base of the tool is the bottom side of the shank.
Standard angles of a single point tool are:
1. Rake angle
It is the slope of the face of the tool away from the cutting edge. It allows the chip to flow over the face. The slope of the face away from the cutting edge towards its back is known as back rake angle. The rake angle towards side is the side rake angle.
Rake angle may also be positive, negative or zero rake angle.
Generally speaking, positive rake angles have greater cutting efficiency from the stand point of cutting force and power requirement. However, the positive rake angle result in fragile cutting edge and are limited to machining softer materials.
A zero rake angle with no slope on tool face is used for turning brass as these metals are removed in short chips exerting little cutting pressure.
Negative rake angles provide a stronger cutting edge and are suitable for cutting high strength alloys. It is used for machining cemented carbide tipped tool.
2. Relief angle
Relief angle prevent the flanks of the tool from rubbing against the surface of the work. It will be always positive. Larger relief angle provide a keener cutting edge. However result in a fragile cutting edge and is only suited for softer materials.
3. Cutting edge angle
The end and side of the tool are ground back at an angle sloping from the nose towards the side of the shank called as end cutting edge angle and side cutting edge angle.
4. Lip angle or cutting angle
It is the included angle when the tool has been ground wedge shaped.
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