1. Mach: 122: Abrasive Machining
Cutting Tool Geometry
Mach: 122: Abrasive Machining

2. CUTTING TOOLS FOR THE LATHE
Cutting Tool Geometry
The most important aspect of a lathe tool is its geometric form:
Side & back rake.
Front & side clearance or relief angles.
Chip breakers.
Fig. I-78 The parts and angles of a tool.
The tool shank is that part held by the toolholder.

3. Cutting Tool Geometry CUTTING TOOLS FOR THE LATHE
The side rake directs chip flow away from the point of cut & provides for a keen cutting edge.
Rake is important to smooth chip flow, for a uniform chip & good finish, especially in soft materials.
Fig. I-78 The parts and angles of a tool.
Grinding a tool provides a sharp cutting edge & the shape needed for the cutting operation.

4. Cutting Tool Geometry CUTTING TOOLS FOR THE LATHE
Fig. I-78 The parts and angles of a tool.
The end relief angle prevents the front edge of the tool from rubbing on the work.
The side relief angle provides cutting action by allowing the tool to feed into the work material.

5. Cutting Tool Geometry CUTTING TOOLS FOR THE LATHE
The side cutting edge angle may vary considerably.
For roughing, it should about 5 degrees.
For squaring shoulders or other light machining angles range 5 to 32 degrees.
Fig. I-78 The parts and angles of a tool.

6. Cutting Tool Geometry CUTTING TOOLS FOR THE LATHE
Nose radius varies according to the finish required.
Fig. I-78 The parts and angles of a tool.
The smallest nose radius that will give the desired finish should be used.

7. Cutting Tool Geometry CUTTING TOOLS FOR THE LATHE tab
In finishing operations with a large nose radius and a light cut, SCEA is not an important factor.
SCEA directs cutting forces back into a stronger section of the tool point & helps direct chip flow away from the workpiece.
It also affects the thickness of the cut.
Fig. I-79 Change in chip width with an increase of the side cutting edge angle. A large SCEA can cause chatter.

8. CUTTING TOOLS FOR THE LATHE
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Cutting Tool Geometry
Fig. I-80 Left- and right-hand roughing tools.
Left-hand tools are shaped just the opposite of right- hand tools.
The right-hand tool has the cutting edge on the left side and cuts to the left or toward the headstock.