Optimal grinding speed depends mainly on graphite hardness, crystallinity, flake integrity, target fineness, and temperature control. Too high speed causes over-grinding, overheating, or flake damage; too low reduces efficiency.
1. Natural Flake Graphite
This type has a layered structure and high value in flake shape — avoid breaking flakes.
- Grinding speed: Medium–low main shaft speed
- Classifier speed: Medium (to retain flake size)
- Rules:
- Reduce speed by 10–15% if flakes are severely broken
- Keep grinding temperature below 60°C to prevent oxidation
- Do not run at maximum speed; stable medium speed gives best yield
2. Amorphous / Microcrystalline Graphite
Softer, easier to grind, lower purity, more abrasive.
- Grinding speed: Medium–high speed
- Classifier speed: Slightly higher for fine powder
- Rules:
- Can increase speed appropriately to improve output
- Watch motor load; avoid overload from high feeding
- Regularly check lining wear due to abrasiveness
3. Synthetic Graphite
High purity, uniform structure, moderate hardness.
- Grinding speed: Stable medium speed
- Classifier speed: Adjustable according to fineness
- Rules:
- Fine grade → slightly lower grinding speed + higher classifier speed
- Coarse grade → slightly higher grinding speed
- Maintain steady speed to avoid particle size fluctuation
4. Spherical Graphite (Battery Grade)
Requires precise shape and narrow particle distribution.
- Grinding speed: Low & stable speed
- Classifier speed: High precision control
- Rules:
- No high-speed impact grinding
- Use gentle grinding mode; avoid over-reduction
- Strict temperature control (≤50°C)
5. Key General Rules for All Graphite Types
- Temperature control
- Graphite oxidizes at high temperature. If mill temperature rises sharply, reduce speed immediately and strengthen ventilation/cooling.
- Fineness adjustment
- Coarser powder: slightly higher grinding speed
- Finer powder: lower grinding speed + higher classifier speed
- Stable feeding
- Uneven feeding causes speed fluctuation. Maintain constant feed rate to keep optimal speed.
- Equipment condition
- Check belt tension, bearing clearance, and motor performance regularly
- Worn liners or grinding rollers will reduce actual grinding efficiency — replace in time to avoid needing excessively high speed
- Avoid resonance
- Do not run at critical vibration speed, which causes instability and poor grinding.
- Flake graphite: Low–medium speed, protect flakes
- Amorphous graphite: Medium–high speed, improve efficiency
- Synthetic graphite: Medium speed, stable particle size
- Spherical graphite: Low speed, precise control
Always adjust speed based on real-time temperature, particle size, and motor load to keep optimal grinding performance.