What are the disadvantages of diamond tools?

Diamond tools, while being extremely hard and offering excellent wear resistance, do have several disadvantages that can impact their use in certain applications:

1. Brittleness: Diamond can be quite brittle, which means it may crack or chip when subjected to shock or impact loads. This limits their use in applications where the tool may experience sudden or heavy impacts.
2. Thermal Stability: Diamond has poor thermal stability. It can burn or undergo graphitization (turn into graphite) at high temperatures. Specifically, diamond starts to graphitize at temperatures above 700°C in the presence of oxygen, which can occur between 455 and 860°C in the air.
3. Chemical Reactivity: Diamond can react chemically with certain metals, such as iron, cobalt, nickel, chromium, and vanadium. This means that diamond tools are not suitable for machining steel and other alloys containing these metals.
4. Cost: Diamond tools are typically more expensive than tools made from other materials, which can be a limiting factor for their use, especially in cost-sensitive applications.
5. Limited to Certain Materials: Due to their reactivity with certain metals, diamond tools are best suited for non-ferrous materials and non-metallic materials like glass, ceramics, and stone, rather than ferrous metals.
6. Tool Wear: Despite their hardness, diamond tools can still experience wear. The wear mechanisms can be abrasion, adhesion, and chipping, especially when machining materials with hard particles like metal matrix composites (MMCs).
7. Fabrication Challenges: Producing diamond tools with complex geometries can be difficult and expensive. The manufacturing process often requires high pressures and temperatures.
8. Limited Ablation Depth: In some processes, such as laser ablation, the depth that can be achieved is limited, which can be a disadvantage for certain industrial applications.
9. Tool Life: While diamond tools have a longer life compared to some other materials due to their hardness, they still wear out over time and require replacement or re-sharpening.
10. Specialized Equipment Required: Using diamond tools often requires machine tools with highly stable spindle rotation and accurate linear axis movement to minimize vibration and tool wear.
11. Microchipping: Diamond tools can experience microchipping of the tool edge if not used under optimal conditions, which can affect the quality of the workpiece.
12. Cooling Requirements: To prevent excessive tool wear, especially when machining steel, cryogenic or other cooling methods may be required, which adds complexity to the machining process.

 

These disadvantages must be carefully considered when selecting diamond tools for a particular application. Despite these limitations, diamond tools are widely used in applications where their hardness and wear resistance provide significant advantages.