Bottom line: find a stable TPU speed by testing extrusion stability first, then balancing surface finish and layer bonding within that limit. Speed above the feed system's capability causes under-extrusion and flow variation. Hardness, feed path and nozzle diameter all change the limit.
What sets the limit
| Factor | Effect |
|---|---|
| Hardness | Softer grades allow less speed |
| Feed path | Direct drive supports higher speed |
| Nozzle diameter | Larger nozzle stabilises flow |
| Temperature | Affects melt flow |
| Retraction | Excessive values limit speed |
Test sequence
- Dry the filament and check the feed path.
- Run a temperature tower.
- Increase speed step by step, watching extrusion.
- Check surface and layer strength.
- Confirm on a taller part.
Costly mistakes
- Copying PLA speeds.
- Exceeding feed capability.
- Compensating only with temperature.
- Ignoring retraction effects.
- Judging from one small test.
Buyer / engineer checklist
- Is the feed path stable?
- Is temperature in the stable window?
- Is extrusion continuous?
- Are surface and layer strength acceptable?
- Was the result repeated?
Share your printer and TPU grade and we can help set the speed range.TPU advice