Investigating the relationship between cutting forces and tool wear mechanisms during milling with carbide end mills involves studying how the forces generated during machining affect tool degradation. This includes axial force, radial force, and torque, which contribute to wear mechanisms like cratering, flank wear, and edge chipping.

Overview of Cutting Forces and Their Impact

1. Axial Force (Fz): Acts along the axis of the tool. It can affect:
   • Flank wear: Consistent high axial forces increase pressure and sliding contact, causing abrasion on the tool's flank surface.
   • Cratering: Indirectly contributes by increasing heat generation, leading to chemical or adhesive wear.
2. Radial Force (Fy): Acts perpendicular to the tool axis. It influences:
   • Edge chipping: High radial forces can lead to mechanical shock and localized stress, resulting in microfractures or edge breakage.
   • Flank wear: Causes lateral sliding motion, exacerbating abrasive wear.
3. Torque (Mz): Represents the twisting moment acting on the tool:
   • Increased torque usually correlates with higher cutting energy, leading to thermal effects that amplify wear mechanisms like cratering.
   • High torque can induce vibration, causing unstable cutting conditions that accelerate edge chipping.

Tool Wear Mechanisms

1. Cratering:
   • Occurs primarily on the rake face due to adhesive and chemical interactions at high temperatures.
   • Influenced by cutting speed and material properties (e.g., titanium alloys can chemically react with carbide tools).
   • Higher cutting forces increase the contact stress and heat, intensifying crater formation.
2. Flank Wear:
   • Progresses as abrasive wear due to contact with the workpiece material.
   • Increased cutting forces lead to higher friction and pressure, accelerating this wear.
   • Common in steel and harder materials due to their high abrasiveness.
3. Edge Chipping:
   • Caused by mechanical shocks or interrupted cutting, often resulting from excessive radial force or tool vibrations.
   • More prevalent in brittle carbide tools when machining tough materials like titanium.

Material-Specific Observations

1. Steel:
   • High hardness causes abrasive flank wear.
   • Elevated cutting forces can lead to thermal softening of the tool, increasing cratering.
   • Edge chipping may occur due to interrupted cuts or hard inclusions in the steel.
2. Aluminum:
   • Lower cutting forces generally reduce flank wear but may lead to material adhesion and built-up edge formation.
   • Adhesion can exacerbate cratering on the tool rake face due to thermal effects.
3. Titanium:
   • High chemical reactivity causes rapid cratering through diffusion wear mechanisms.
   • High cutting forces and poor thermal conductivity lead to concentrated heat at the cutting edge, promoting edge chipping and flank wear.

Investigation Methods

• Force Measurement: Use a dynamometer to measure cutting forces during milling operations.
• Wear Analysis: Examine tool wear under a microscope or scanning electron microscope (SEM) to identify mechanisms.
• Material Properties Analysis: Analyze workpiece material properties (e.g., hardness, chemical composition) to understand their contribution to wear.
• Finite Element Simulation: Model cutting forces and wear progression under different conditions.

Recommendations for Optimization

1. Cutting Parameters:
   • Use lower feed rates and cutting speeds for hard materials to reduce cutting forces and tool wear.
   • Optimize depth of cut to balance cutting forces and tool life.
2. Tool Coatings:
   • Apply wear-resistant coatings like TiAlN to reduce cratering and flank wear.
3. Coolants and Lubricants:
   • Use cutting fluids to manage heat and reduce adhesion in materials like aluminum and titanium.
4. Tool Geometry:
   • Design tools with reinforced cutting edges to resist chipping under high radial forces.