LESSON 2.2 · 2:25 · CHAPTER 2 · THE EXTRUDER
Why big nozzles work
Filled melts shear-thin (power-law index n ≈ 0.3 for CF-ABS), so the pressure to push them through a smaller nozzle rises far less than for a simple liquid: R^−(3n+1) instead of R^−4.
Predict · at 0:55 in the video
Same flow, nozzle radius halved, power law index 0.3. By what factor does the pressure rise?
About 3.7 times. Not sixteen. The pressure goes as the radius to the power of minus three n plus one.
Further reading
This course is our own. These books go deeper.
- The economics of Big Area Additive Manufacturing, Post et al., Solid Freeform Fabrication Symposium, 2016
- Additively manufactured carbon fibre-reinforced composites: state of the art and perspective, van de Werken et al., Composites Part A, 2020
About the numbers
Simulations in this lesson are our own. Where a number rests on an assumption or a single source, the video marks it with an asterisk and says where it comes from.
Up next · 2.3 · 2:12Fibre makes the melt fight back