Gallery, Projects and General > How do I??
HDPE Recycling, centrifuge and all that jazz!
John Hill:
Right, so I want to recycle HDPE and I want to produce luverly plastic billets that I can use to make stuff.
I have an oven, a big stash of suitable HDPE scrap and some short lengths of steel water pipe (2.5" or so) which I have used to mould the HDPE.
The problem with my operation is how to get pure plastic without air inclusions? My thought is to put the hot plastic in the water pipes and centrifuge them to expel the air.
The hot plastic is not exactly fluid but it is almost pour able.
That is the idea, so far!
ddmckee54:
A vacuum chamber might work better. Unless you put the centrifuge in the oven the HDPE will cool and be set up before you could get the air spun out of it.
You've already got the steel pipe so you're half way to a vacuum chamber. Clamp the pipe between a couple of steel plates with some silicone sheets for gaskets, a vacuum port on one end, and Bob's your uncle - you've got a vacuum chamber. You could even wrap some heaters around the pipe to keep the HDPE hot while you apply the vacuum.
If you're really serious about this, have you thought about an extruder? The extrusion process removes the entrained air and you can mold whatever shaped billet you want. You probably already know about it, but if not check out the Precious Plastic website. https://preciousplastic.com/
awemawson:
There is a thread on the forum about machineable wax made from HDPE & MDPE
https://www.madmodder.net/index.php/topic,13394.msg161114.html#msg161114
There are others
John Hill:
--- Quote from: ddmckee54 on July 14, 2023, 12:38:04 PM ---A vacuum chamber might work better. Unless you put the centrifuge in the oven the HDPE will cool and be set up before you could get the air spun out of it.
You've already got the steel pipe so you're half way to a vacuum chamber. Clamp the pipe between a couple of steel plates with some silicone sheets for gaskets, a vacuum port on one end, and Bob's your uncle - you've got a vacuum chamber. You could even wrap some heaters around the pipe to keep the HDPE hot while you apply the vacuum.
If you're really serious about this, have you thought about an extruder? The extrusion process removes the entrained air and you can mold whatever shaped billet you want. You probably already know about it, but if not check out the Precious Plastic website. https://preciousplastic.com/
--- End quote ---
I have discussed a vacuum chamber on another site and the message I got is that a very high vacuum would be needed and even then there was doubt that the air would flow in the plastic.
The Precious Plastics site is very interesting but it looks like I would be up for kilobux by the time I had bought/built shredder, extruder, press etc and that makes me hesitate.
John Hill:
It is interesting that no one on any site is supportive of the centrifuge idea so I will just leave that aside for the meantime.
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