Graphite Plate Drilling Tool Wear

Hydrogen fuel cells commonly use three types of bipolar plates: graphite plates, composite plates, and metal plates. Graphite plates are often preferred due to their excellent properties. However, these properties also demand high performance from the machining tools, especially during milling and drilling processes.

Challenges in Machining Graphite Plates

1. Material Characteristics: Graphite is a non-metallic, brittle material with an uneven, porous structure. This makes it prone to chipping during machining.
2. Thinness and Deformation: Graphite plates can be as thin as 1.8mm to maintain performance, making them susceptible to deformation and loosening during machining. Clamping methods significantly impact the degree of deformation and surface perpendicularity.
3. Drilling Issues: The brittle and thin nature of graphite plates causes sudden changes in axial force when drilling, making it difficult to ensure the diameter, perpendicularity, and quality of the holes. This can lead to chipping and workpiece damage.
4. Dust Accumulation: Graphite dust easily adheres to the workpiece and tools, accelerating tool wear and affecting the surface quality of the processed workpiece.

Suitable Tools for Drilling Graphite Plates

The market offers various tool materials, including high-speed steel (HSS), carbide, cubic boron nitride (CBN), ceramic, diamond, and diamond-coated tools. However, CBN and ceramic tools are primarily used for ferrous materials and are not suitable for graphite machining. Among the remaining tool materials, here are some considerations:

• High-Speed Steel (HSS) and Carbide Tools: These tools are less suitable for graphite machining due to their lower hardness. Graphite particles can quickly dull the cutting edge, making them unsuitable for high-quality surface and dimension requirements.
• Diamond Tools: These are the ideal choice for drilling graphite plates. Diamond tools combine base material toughness with wear resistance, making them highly effective for machining graphite. Diamond-coated tools are also an excellent option due to their durability and extended tool life.

Recommendations for Tool Selection and Use

• Choose Diamond Tools: Due to their superior wear resistance and ability to maintain sharp cutting edges, diamond tools are the best choice for drilling graphite plates.
• Optimize Clamping Methods: Proper clamping techniques can minimize deformation and ensure better machining accuracy.
• Control Dust: Implement measures to manage and reduce graphite dust during machining to prevent tool wear and maintain surface quality.