LESSON 6.7 · 1:51 · CHAPTER 6 · CHOOSING AND HANDLING A MATERIAL
Purge across the gap
Switching between polymers that melt 150 K apart needs a purge compound that works across both, or the old resin degrades or freezes in the barrel.
Predict · at 0:34 in the video
You change from carbon fibre PEI, nozzle about 410, to carbon fibre ABS, about 254. Why can't you just feed the ABS in?
Because there's no temperature where both behave. So you push a purge compound through, one with a window wide enough to span both. Some are rated from 200 to 410.
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 · 7.1 · 1:54Warp grows with length squared