Understanding the "Built-up Edge"

Understanding the inevitability of tool wear in CNC machining is critical. Despite preventive measures or optimizations, tools inevitably degrade due to inherent metal-on-metal friction.

Universal Nature of Tool Wear

All cutting tools worldwide – regardless of brand quality or specialization – experience wear. This is not a manufacturing defect, but a natural outcome of cutting operations. Wear progression depends on multiple factors:

• Tool and insert selection
• Workpiece material properties
• Machine tool performance
• Coolant application
• Parameter optimization

No current insert technology achieves indefinite durability.

Built-up Edge (BUE)

Formation Mechanism

BUE develops when workpiece material pressure-welds to the cutting edge under conditions of:

• Chemical affinity between materials
• High contact pressure
• Insufficient temperature for clean shearing

Identification & Effects

Visual characteristics include:

• Glossy material deposits on cutting edge or flank face
• Cratering on the rake face
• Eventual edge chipping

Critical consequence: BUE detachment often removes tool material fragments, accelerating flank wear and edge failure.

High-Risk Materials & Conditions

• Gummy materials:
  • Non-ferrous metals
  • Superalloys
  • Stainless steels
• Low-speed machining regimes
• Insufficient feed rates

BUE Mitigation Strategies