LESSON 3.3 · 2:07 · CHAPTER 3 · THE BEAD
Corners make blobs
A screw extruder lags its command, so when the head brakes into a corner the extra melt lands there, and a thin neck follows on the way out.
Predict · at 0:41 in the video
Flow lags by 0.08 seconds. The head brakes from 200 to 50 millimetres a second into a corner, on a bead of 107 square millimetres. How much extra plastic lands in the corner?
About 1,280 cubic millimetres. The bead area, times the drop in speed, times the lag. 107 times 150 times 0.08.
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 · 3.4 · 2:08Starts thin, stops fat, the seam walks