Built-up edge (BUE) is when workpiece material welds to the cutting edge during machining, then breaks off taking carbide chunks.
Recognizing BUE
- Surface finish degrades progressively
- Cutting forces increase over time
- Visible material smear on insert when removed
- Insert flank has irregular wear pattern
Why BUE Forms
Thermo-mechanical process. At certain temperatures, chip material plasticizes and welds to tool. BUE temperature window:
- Aluminum: 200-400°C
- Stainless steel: 600-800°C
- Copper: 150-300°C
- Carbon steel: 500-700°C (rare with modern coated tools)
Solution 1: Move Out of Temperature Window
Increase cutting speed by 30-50%. Counter-intuitively, faster = cooler chip in this regime.
Solution 2: Change Tool Surface
- Polished uncoated — Best for aluminum
- ZrN coating (gold) — Slick, prevents aluminum welding
- DLC coating — Premium for high-Si aluminum
- PVD AlTiN — Best for stainless BUE
Solution 3: Geometry
- HIGH POSITIVE rake (15-25°)
- Sharp edge for finishing
- Variable helix end mills
Material-Specific Tips
Aluminum BUE: 2-flute or 3-flute, high helix (45°), polished/ZrN, Vc above 300 m/min.
Stainless BUE: PVD AlTiN, Vc 150-200 m/min, feed above 0.15 mm/rev, EP coolant high pressure.
Copper BUE: Polished uncoated, sharp positive rake, cutting oil (not water-based).
Browse BUE-resistant inserts.
Shop Related Products at HOOGUU
