Tool Wear

Question 1

What two locations does gradual wear occur?

Answer 1

Crater Wear - occurs on top rake face

Flank Wear - occurs on flank (side of tool)

Question 2

What are different types of tool wear?

Answer 2

Abrasion - dominant cause of flank wear

Adhesion - high pressure localised fusion

Diffusion - loss of hardening atoms at tool-chip boundary (contributes to crater wear)

Plastic deformation - contributes to flank wear

Question 3

What is tool life and what is the equation?

Answer 3

Tool life - length of cutting time that a tool can be used or a certain flank wear value has occurred (0.508mm)

vT^n = C

v = cutting speed
n = cutting exponent
C = cutting constant
T = tool life

Question 4

What are the 3 modes of failure of a tool and how do they occur?

Answer 4

Fracture failure: Cutting force becomes excessive and/or dynamic, leading to brittle fracture

Temperature Failure: Cutting temperatures is too high for the tool material

Gradual Wear: Gradual wearing of the cutting tool