I did some testing this afternoon on the granular extruder I recently put together. Things didnt go so well..
It turns out that the ‘high temperature’ solder I used to seal the end wasn’t up to the task. I first tried to extrude the HDPE at a lower temperature, around 140°C, but I wasn’t able to get it flower. Once I turned the temperature up a bit hight, around 180°C, it started to extrude quite well for 15 seconds or so until the solder melted. At this point molten plastic was extruded from every opening, ruining the barrel.
On the up side, I now know for sure that the auger drill bit can provide enough pressure to extrude successfully. However, at this point the rotating of the auger drill bit was still done by hand. My next attempt will be to try and braze on a flat section on the end end of the pipe with silver brazing rod. Silver brazing rod doesnt even begin to melt until well over 450°C so it should be well up to the task.
Also today, my good friend who supplied the original HDPE granules stopped by and dropped off a slightly bigger batch.
This 30Kg box (66 pounds) of food grade HDPE granules is all the motivation I need to press on and find a workable way of extruding it. That is until my Mendel parts start to arrive and I get distracted by its construction.