10 Questions
What is a potential issue with large positive rake angles at high cutting speeds?
Tool breakage is more likely
Which type of tools are generally preferred for materials like ceramic and diamond due to their hardness and low toughness?
Tools with negative rake angles
In what range are rake angles typically used for cemented carbide tools?
-5° to -10°
What characteristic makes materials like ceramics suitable for negative rake angles?
Brittle nature
Why do negative rake angles provide greater strength at the cutting edge?
Enhanced heat conductivity
What is a common downside associated with negative rake angles in terms of surface finish?
Poorer surface finish
How does a positive rake angle affect the tool's strength at the cutting edge?
Decreases strength
What is the primary advantage of negative rake angles in terms of cutting forces?
Increased cutting forces
Which type of tools are more prone to tool failure under large positive rake angles?
"Ceramic tools"
In which scenario are high positive rake angles more likely to cause tool breakage?
High cutting speeds and intermittent cuts
Study Notes
Cutting Tool
- A cutting tool has one or more sharp cutting edges and is made of a material harder than the work material.
- The cutting edge serves to separate a chip from the parent work material.
Single-Point Cutting Tool
- A single-point tool has one cutting edge and is used for operations such as turning.
- The cutting edge is usually rounded to a certain radius, called the nose radius.
- During machining, the point of the tool penetrates below the original work surface of the part.
Multi-Point Cutting Tool
- Multiple-cutting-edge tools have more than one cutting edge and usually achieve their motion relative to the workpart by rotating.
- Drilling and milling use rotating multiple-cutting-edge tools.
Tool Geometry
- The rake face is the surface over which the chip, formed in the cutting process, slides.
- The flank face is the surface(s) over which the surface, produced on the workpiece, passes.
- The cutting edge is a theoretical line of intersection of the rake face and the flank surfaces.
- The cutting wedge is the tool body enclosed between the rake and the flank faces.
- The wedge angle is defined as the angle between flank and rake face.
Rake Angle
- Positive rake angle tools have a thinner cross section, which can cause tool breakage with high cutting speeds or intermittent cuts.
- Negative rake angles are generally preferred for ceramic, diamond, and cubic boron nitride tools due to their brittle nature.
- Negative rake angles provide greater strength at the cutting edge, better heat conductivity, and a poorer surface finish.
- Negative rake angles make the tool more blunt, increase the strength of the cutting edge, cause high compression, and increase the cutting forces.
Test your knowledge on machining processes, cutting tools, and single-point cutting tools used in manufacturing. Learn about the functions and materials of cutting tools along with their applications in shaping work materials.
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