In the field of super-hard material processing, Tungsten Carbide (Carbide) is revered for its extreme hardness (HV 1200–1800), exceptional wear resistance, and high-temperature stability. It is the material of choice for manufacturing molds, cutting tools, mining equipment, and wear-resistant parts.
However, the very characteristic that makes Carbide valuable—its "super-hardness"—makes it incredibly challenging to machine. Traditional carbide tools are simply not up to the task, often suffering from edge chipping, rapid wear, or catastrophic failure.
Therefore, selecting the correct insert material is the single most critical factor in successfully machining Tungsten Carbide.
1. The Challenge: Why is Carbide Hard to Cut?
Processing Tungsten Carbide presents three distinct hurdles:
1. Hardness Mismatch: The hardness of Tungsten Carbide far exceeds that of steel. Conventional WC-Co carbide inserts lack the necessary hardness, leading to rapid passivation (dulling) of the cutting edge.
2. brittleness: Carbide is brittle. Interrupted cuts or unstable feed rates can easily cause the tool tip to micro-crack or chip.
3. Thermal Issues: The process generates immense heat. If the tool lacks thermal resistance, it accelerates chemical wear and diffusion wear.
2. The Solution: Super-Hard Tooling Materials
To overcome these challenges, the industry relies on two categories of super-hard materials: PCD and CBN. The choice depends largely on the Cobalt (Co) content of the workpiece.
Option A: PCD (Polycrystalline Diamond) Inserts
● Best For: Tungsten Carbide with Low Cobalt content (<10%).
● Why: Diamond is the hardest material known to man (HV 8000–10000), allowing it to cut through the hard Carbide grains effectively.
● Caution: Diamond has a chemical affinity with iron-group metals (like Cobalt) at high temperatures. Machining high-cobalt carbide with PCD can lead to a chemical reaction that shortens tool life.
Option B: CBN (Cubic Boron Nitride) Inserts
● Best For: Tungsten Carbide with High Cobalt content (>10%) or Steel-Bonded Carbides.
● Why: CBN offers superior chemical stability compared to PCD, especially when interacting with the metal binder phase (Cobalt) in the carbide.
● Performance: While its hardness is slightly lower than diamond (HV 4500–5000), CBN excels in impact resistance and thermal stability, making it ideal for tougher carbide grades.
3. Selection Guide: Matching the Tool to the Application
To ensure efficiency and cost-effectiveness, use the following selection criteria:
● Low Cobalt Carbide (e.g., YG3, YG6):
◇Recommendation: Prioritize PCD inserts.
◇Parameters: Use low feed rates and high cutting speeds.
● High Cobalt or Steel-Bonded Carbide:
◇Recommendation: Use High-Content CBN inserts.
◇Reason: This avoids the chemical reaction between diamond and cobalt, preserving tool life.
● Complex Profiles or Interrupted Cuts:
◇Geometry: Choose PCD or CBN inserts with a Negative T-land (Chamfer) or reinforced edge. This significantly improves edge strength and resistance to chipping.
● Cooling Strategy:
◇Recommendation: We suggest MQL (Minimum Quantity Lubrication) or Dry Cutting.
◇Why: Avoid flooding with water-based coolants, as they can accelerate oxidation of the tool at high temperatures.
Conclusion
Machining Tungsten Carbide is not a task for ordinary tools. It requires a scientific approach to tool selection.
By matching the insert material—PCD or CBN—to the Cobalt content and structure of the specific Carbide grade, manufacturers can achieve high-quality results, improved efficiency, and lower costs. As super-hard tool technology continues to advance, the mechanical machining of Carbide is becoming a more economically viable solution than ever before.
Need high-performance PCD or CBN inserts for your Carbide machining project? Contact us today for a technical consultation.
