## Common ground
All options are machines used in the processing of glass, either cold or hot, for manufacturing or shaping.
## Options at a glance
**8464.20 – Cold working: grinding/polishing**
- **Defining trait:** Performs surface finishing via grinding or polishing without heating the glass.
- **Typical examples:** Glass polishing machines, edge grinders for mirrors.
- **Best fit when:** The machine modifies glass surfaces by abrasion at room temperature.
**8464.90 – Cold working: other than grinding/polishing**
- **Defining trait:** Performs cold processing not involving grinding or polishing (e.g., cutting, drilling, etching).
- **Typical examples:** Glass cutters, laser drillers, sandblasting machines.
- **Best fit when:** The machine alters shape or structure without surface smoothing.
**8475.21 – Hot working: optical fibre production**
- **Defining trait:** Specifically designed for manufacturing optical fibres or their preforms using high heat.
- **Typical examples:** Preform makers, fibre drawing towers.
- **Best fit when:** The machine produces long, thin fibres from molten glass (e.g., telecoms-grade).
**8475.29 – Hot working: other than optical fibres**
- **Defining trait:** Uses heat to shape or form glassware, excluding fibre production.
- **Typical examples:** Glass blowing machines, hot bending furnaces, float glass forming lines.
- **Best fit when:** The machine melts or molds glass into shapes like bottles, panels, or sculptures.
## Key differences
| Feature | 8464.20 | 8464.90 | 8475.21 | 8475.29 |
|-----------------------|---------------|---------------|------------------|------------------|
| Temperature | Cold | Cold | Hot | Hot |
| Primary function | Surface finish| Shape alteration | Fibre production | Glassware shaping |
| Key process | Grinding/polishing | Cutting/drilling | Drawing preforms | Blowing/bending |
## How to choose
1. Does the machine use heat? → No → 8464.20 or 8464.90
2. Is it for polishing or grinding? → Yes → 8464.20
3. Is it for making optical fibres? → Yes → 8475.21
4. Does it shape glass by melting (e.g., blowing, bending)? → Yes → 8475.29
## Overlaps & pitfalls
- A machine that both cuts cold glass and heats it for shaping could fit 8464.90 or 8475.29; priority depends on the **main function**.
- "Hot working" includes both fibre drawing and general forming—only 8475.21 is specific to fibres.
- If unclear, use the **primary process**: surface finish (grinding/polishing) vs. structural change vs. fibre production vs. bulk shaping