Cutting tool materials and tool productive life

Question 1

Identify the conditions that cutting tool materials are exposed to and what properties they must have.

Answer 1

Cutting tool materials are subjected to:

• High temperatures
• Contact stresses
• Abrasion

All Cutting tool materials should have:

• Hardness
• Toughness
• Wear resistance
• chemical stability

Question 2

What is Cutting tool wear and Common types

Answer 2

Tool wear describes the gradual failure of cutting tools due to regular operation.

It is a term often associated with solid cutting tools, tooling inserts, or drill bits that are used with machine tools.

Types of tool wear:
Flank wear in which the portion of the tool in contact with the finished part erodes. Can be described using the Tool Life Expectancy equation.

Crater wear in which contact with chips erodes the rake face. This is somewhat normal for tool wear and does not seriously degrade the use of a tool until it becomes serious enough to cause a cutting-edge failure.

Question 3

For the fluids and lubricants required, explain their benefits and how they can be applied.

Answer 3

Cutting Fluids Benefits:

• Reduce friction and wear
• Reduce energy consumption
• Cool the cutting zone
• Protect machined surfaces

Fluid Actions:

• Capillary Action
• Small molecular size
• Proper wetting characteristics

Types of Cutting fluids:

• Oils
• Emulsions
• Semi-Synthesis
• Synthetics

Methods of Applications:

• Flood cooling
• Mist cooling
• High-pressure refrigerated systems

Question 4

Explain Taylors equation for tool life expectancy and how to calculate it.

Answer 4

Definition: Provides a good approximation for productive cutting tool life.

Multiply:

VcT^n = C

Vc = Cutting surface speed (m/min)
T = Tool life (minutes)
D = Depth fo cut (mm)
F = Feed rate (mm/rev)
"n" and "C" are constants found by experimentation or published data; they are properties of tool material, workpiece and feed rate.  

Cutting speed x Tool life^n = C