A tool is a wedge shape object that is made of hard materials as high carbon steels, satellite, ceramics, diamonds and most commonly abrasives. Hardness is the main requirement of the tool. It should have resistance to with stand cutting forces that are applied on the work piece with enough hardness.
The tool material should possess wear resistance, toughness, hot hardness, thermal conductivity, specific heat and coefficient of friction etc.Advertisement:
All these required properties are to be very high for a good tool. According to the number of cutting edges the tools are classified as single point cutting tool and multi pint cutting tool.
Single point cutting tool:
It is simpler form of cutting tool that have only one cutting edge. Shear tools, lathe tools, planner tools, boring tools etc. are the examples of single point cutting tool.
- Shank: the shank is used as a tool holder. It is a main body of the tool. It is generally gripped in the tool frame.
- Flank: It is a surface of the cutting edge or the surface adjacent to the cutting edge of the tool.
- Face: It is the surface of the tool where the chip slides along the top of this surface.
- Base: Base is a bearing surface of the tool. This base is held in a tool holder or it is directly clamped in the tool post.
- Heel: Heel is an intersection to the flank and base of the cutting tool. It is a curved portion at the bottom of the tool.
- Nose: This is a point where the base cutting edge and the side cutting edge gets intersected.
- Cutting edges: It is a face edge on the face of the tool that removes the material from the work piece. There are two cutting edges as side cutting edge and end cutting edge, where the side cutting edge is major cutting edge and the end cutting edge is minor cutting edge.
- Tool angles: Tool angle splay a vital role in the tool cutting action. The tool that comes with proper angles will reduce failures as tool breaking due to high work forces on the work piece. The metal cutting is done more efficiently with generation of little heat.
- Noise radius: The nose radius will provide long life and also good surface finish with it sharp point on the nose. It has high stress and leaves in its path of cut. Longer nose radius will give raise to chatter.
- Side cutting edge angle:
It is the angle in between the side cutting edge and the side of the tool shank. This angle is also referred as lead angle.
- End cutting edge angle:
End cutting edge angle is in between the perpendicular line of the tool shank and the end cutting edge.
- Side relief angle:
The portion of side flank that is immediate below to the side cutting edge and the base perpendicular line of the cutting tool.
- End relief angle:
Relief angle is in between the base perpendicular line and end flank.
- Back rake angle:
The angle measured along the plane perpendicular through the side cutting edge in between the tool face and the perpendicular line to the base.
The tool slope of the face is measured from the nose and towards rack. If the slope measured is downwards then it is negative back rake.
- Side rake angle:
The angle in between the parallel line of the base and the face of the tool that is measured it the plane perpendicular to the side edge and base.
The slope of the tool face is measured from the cutting edge and if the obtained slope is towards the cutting edge the angle is negative side rake.
If the obtained angle is away from the cutting edge then the angle is positive side rake angle. The rake angle will be zero if no slope value is obtained.
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