Cutting Tool Nomenclature

What are the names given to the parts and angles of a lathe cutting tool?

See Figure 7–29.

Where can these cutting tool angles be obtained for grinding HSS bits? Appendix I of this book and Machinery’s Handbook under Cutting Tools.

Cutting Tool Mechanics

How do cutting tools remove metal from the workpiece? As the tool enters the workpiece, material just ahead of the tool is deformed, sheared from the workpiece, and flows into the space above the tool in the form of a chip, Figure 7–30. The mechanical energy supplied to the lathe is converted to heat as shearing occurs and as the metal slides along the cutting tool surface.

What factors determine how well a cutting tool works?

• The most important factor is tool shape, particularly the back rake and side rake angles, Figure 7–29. In general, side rake is more important because more cutting is done on the sides of tools than on their ends.

• The position of the cutting edge in relation to the workpiece is also very important and explained in this chapter under the section heading Lead Angle.

• Other factors which affect tool shape are relief or clearance angles—the taper on non-cutting tool surfaces, to prevent rubbing or dragging the tool against the work.