## Common ground
All options are grinding balls used for material processing, differing only in material composition.
## Options at a glance
**6909.11 – Porcelain/China**
- **Defining trait:** Made from vitrified clay with high hardness and chemical resistance.
- **Typical examples:** Lab-scale ball mills, pharmaceutical grinding.
- **Best fit when:** High purity and corrosion resistance needed; low wear on equipment.
**6909.12,6909.19 – Ceramic**
- **Defining trait:** Engineered non-metallic material with high hardness and toughness (e.g., alumina).
- **Typical examples:** Industrial powder processing, abrasive-free grinding.
- **Best fit when:** Need for wear resistance and low contamination in sensitive applications.
**7018.20,7020.00 – Glass**
- **Defining trait:** Brittle but chemically inert; used where metal contamination must be avoided.
- **Typical examples:** Food, cosmetics, or pharmaceuticals with strict purity needs.
- **Best fit when:** Non-metallic, non-reactive grinding required; low impact forces.
**7325.91 – Cast Iron/Steel**
- **Defining trait:** High density and durability; prone to wear and corrosion.
- **Typical examples:** Heavy-duty mining or cement grinding.
- **Best fit when:** High impact resistance and cost-effectiveness are key.
**7326.11 – Forged/Stamped Iron/Steel**
- **Defining trait:** Superior strength and uniform grain structure from shaping under heat/pressure.
- **Typical examples:** Precision industrial mills, long-life applications.
- **Best fit when:** High mechanical performance and longevity required.
**8113.00 – Cermet**
- **Defining trait:** Composite of ceramic and metal; combines hardness with toughness.
- **Typical examples:** Aerospace or high-performance tooling.
- **Best fit when:** Extreme wear resistance and thermal stability needed.
## Key differences
| Material | Hardness | Wear Resistance | Corrosion Resistance | Cost |
|----------------|----------|------------------|------------------------|----------|
| Porcelain/China| Medium | Medium | High | Low–Med |
| Ceramic | High | Very High | High | Med |
| Glass | Medium | Low | Very High | Low |
| Cast Iron/Steel| High | Medium | Low | Low |
| Forged Steel | Very High| Very High | Low–Med | High |
| Cermet | Very High| Extremely High | Med–High | Very High|
## How to choose
- Is the application in food, pharma, or cosmetics? → 7018.20,7020.00
- Does it need high wear resistance and low contamination? → 6909.12,6909.19
- Is metal contamination unacceptable? → 7018.20,7020.00 or 6909.12,6909.19
- Is high impact and durability critical? → 7325.91 or 7326.11
- Is extreme performance (heat, wear) required? → 8113.00
## Overlaps & pitfalls
- Ceramic (6909.12,6909.19) and porcelain (6909.11) may overlap in use; porcelain is a type of ceramic but less dense.
- Glass balls are fragile—may break under high impact, misleadingly labeled as "durable."
- Forged steel (7326.11) vs. cast (7325.91): forged has better strength; choose based on performance needs.
- **No priority rule given**—choose based on the product’s MAIN function: wear resistance, purity, or mechanical strength