It was not that difficult but since this is my first HDPE project, I had to invest a little bit of thinking.
IOT save time between cycles I made a poor mans pallet that allowed me to unload the finished parts and load the next stock within 2 minutes.
It is just a 400x400x18 MDF with two locating pins asymmetrically positioned on left and right sides.
On top of this I had a plastic reinforced laminated layer with the HDPE held down with wood screws and the whole was secured down with M6x30 at all four corners. This was the surface that was faced to make it both smooth and parallel.
It was critical to apply my bodyweight while screwing in those little torx screws and going from one to the nearest screw not the furthest like I would do with metal. This ensured that the 15mm thick plastic was not warped.
I also had to make room (countersink) for the protruding plastic in the wood pallet.
This is the part I hate, starting every new project, no dust extraction to listen to the machine…
It took 1 hour 50 minutes to machine the 4 halfs with 22000 RPM, DOC 3mm, WOC/optimal load 2,4mm, feed 1960 mm/min
with this endmill: https://datronshop.de/cnc-fraeswerkzeuge/zweischneider/zweischneider-konturfraeser.html
Bonding: After several test pieces bonded with epoxy and broken I ended up with sanding the surface with 80grit. This reduced the gap between layers and provided “hairy” grip surface for the glue.
(The upper piece is the sanded one.)
Without sanding the epoxy can be pealed of as you can see the squeeze out on the side of these testpieces.