CNC Cutting Tool Geometry & Selection 4

Question 1

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

Accepted Answer

Machining hardened steels above 45 HRC

Answer

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

Question 2

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

Accepted Answer

Axial cutting force direction and chip evacuation

Answer

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

Question 3

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

Accepted Answer

Lower cutting forces and reduced heat generation

Answer

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

Question 4

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

Accepted Answer

The width of the cutting path measured perpendicular to feed direction

Answer

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

Question 5

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

Accepted Answer

Round (R-shape)

Answer

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

(CNC) Computer Numerical Control Machinist Technical Practice Test

(CNC) Computer Numerical Control Machinist Technical Practice Test

CNC Cutting Tool Geometry & Selection 4