Cutting Tool Geometry & Selection Flashcards

When should CBN (Cubic Boron Nitride) inserts be selected over carbide for turning?

Answer: Machining hardened steels above 45 HRC

CBN is the preferred choice for hard turning of steels above 45 HRC, as carbide tools wear rapidly under those conditions.

The helix angle on an end mill affects which of the following most directly?

Answer: Axial cutting force direction and chip evacuation

A higher helix angle increases the axial (upward) cutting force component and improves chip evacuation from the flutes.

What is the primary advantage of a positive rake angle cutting tool?

Answer: Lower cutting forces and reduced heat generation

Positive rake angles allow the tool to slice rather than scrape, resulting in lower cutting forces, less heat, and better surface finish.

In a face milling operation, what does 'radial depth of cut' (stepover) represent?

Answer: The width of the cutting path measured perpendicular to feed direction

Radial depth of cut (ae) is the lateral engagement of the cutter into the workpiece, measured perpendicular to the feed direction.

Which insert shape provides the most cutting edge strength for heavy interrupted cuts?

Answer: Round (R-shape)

Round inserts distribute cutting forces over the entire circumference, providing maximum edge strength and the greatest number of indexable positions.

What is the function of a tool's 'back rake angle' in a single-point turning tool?

Answer: Controls chip flow along the tool shank length

Back rake angle (inclination of the face away from the feed direction) controls whether chips flow toward or away from the machined surface.

When machining titanium alloys, which cutting condition is most critical to prevent premature tool failure?

Answer: Maintaining consistent chip load and avoiding rubbing

Titanium work-hardens and retains heat in the chip; maintaining consistent chip thickness prevents rubbing, work hardening, and rapid tool wear.