Slow molding

in V1.0 we made a rotation machine. However overtime we noticed applications are quite limited with this technique.
We decided to postpone and replace it with another technique, slow molding. You put a pressured mold in an oven and wait for it to melt in it’s final shape. The core of this machine is (like the rotation) and old oven. We got some materials today.

got these beauties. Next stop making a mold and do a testrun under pressure

Not a bad idea, although we haven’t really focussed on efficiency with this machine yet that seems very easily doable and can gain a lot of speed. Will look into it! Thanks for sharing feedback!

Great work guys! 🙂

It appears this process is similar to compression moulding:

It seems the big advantage over injection moulding is the ability to create large parts with a basic/cheap machine, I wonder if cycle times could be increased by having a locking bolt that could be tightened on the ram arm to hold the compression so the tool and part could be removed from the oven for the cooling phase, allowing another tool to enter the oven for the heating/compression phase.

I look forward to seeing if you are able to create more complex parts using this machine 🙂

Hi @jordanwatson, good to see you here! The bed is about 45x45cm, its based on a household oven, so it depends a little which you find. Pressing external could also work, i just wanted a single machine that could do trick. If your going for efficiency an external press seems like a good way to go. We made the carjack in the bottom just to make the framework smaller. Otherwise you have a framework above and under the oven.

Keeps us in the loop about your project. Would love to see your external press experience!

Hi Dave & the rest of the community!

Im part of a small workshop based in London UK trying to develop a similar form of manufacture for ourselves so that we can create products from recycled plastic. Im interested in your slow moulder, What was the internal bed size of this oven and also the block size you have pressed? Id like to get a good 45cm square sheet made for a chair seat and after looking at this am now thinking of using an oven. Originally we thought to heat the plastic externally (in a kiln etc) then put in the press afterwards using a hydraulic press or fly press.

What benefits have you found from heating the plastic and pressing at the same time? also whats the time frame for something like this? We want to make on batch so need it to be quite quick which was a benefit to having external presses as we can make more than one press.

One last quick one, why the decision to move the carjack to the bottom?

Super exciting stuff great that there is more people taking this into their own hands!


Slowmolding finished up and gave it a spray paint!

Not much detailed measurement during prototyping, fully focussed on making it actually work. We’ll dive into that when the machines are getting more mature.

Are you measuring emissions at all? I wonder if this makes less fumes than your other melter.

Liked how this machine works, building a bigger more robust version. *it’s upside down

Added a carjack on the oven to build enough pressure in the mold. Now the plastic is pressed into a solid block.

It did not went as plannend. Most of the plastic was still in its original form, only a thin layar on the outside was molten properly. Although the temperature should be high enough it probably needed more melting time and power. Next try with more pressure and patience

First attempt to see whether the technique works . A mold to put in the oven. It’s a very basic cube which you fill up with plastic waste, heat it and then press it into a solid block.