Heatable mold for bioplastic + edible materials v4
Since we are working on biodegradable and edible materials for version 4 we stumbled into a few challenges working with the „classic“ precious plastic machines we have at the workshop.
Most biodegradable materials harden by water evaporation and unlike plastic need heat or air to dry. In addition to this it seemed to make sense to separate edible materials from plastic machines. Simply health wise 😉
So we started to wonder what a machine for molding biodegradable materials could look like and after first experiments and building different molds from wood and welded metal to use for our materials from bran and potato peels (find out more about the recipes here: https://davehakkens.nl/community/forums/topic/experiment-with-future-plastic-alternatives-v4/) it turned out that they all worked well under heat and pressure, however molding the materials into a more three dimensional shape like a bowl seemed to be harder, since the material struggles to spread up the walls of the mold.So we wondered, do we have to build a giant vibrator to put under the press, so that the material spreads better while being pressed? Or do we simply need more pressure?
The latter in mind I spend the last week making a solid mold from aluminum to be able to apply a lot (like 10 metric tons) of pressure with the manual press we have here. In addition to it I added a heating element (a hot plate from the scrapyard in combination with a PID Controller) to be able to heat it up while pressing. Kind of trying to build a low tech version of a machine like they have at biotrem, I guess: https://www.youtube.com/watch?v=mn6sYHb2w80
Last night we finally finished all the milling and put everything together, so I’m really excited to see how the first molding test will turn out today!
I’ll keep you posted on the results and let me know if you have any ideas or suggestions!
Love from Eindhoven!
Oh yeah and check out these excited people discussing the temperature of the mold 😉
nice process! how does it taste?
@ Thomas: Thank you. Its taste is as hot and crisp and tasty as the two boys in the picture suggest 😉
So last night we made the first try outs with wheat bran (lighter one) and potato peels (dark one). Check out the pictures below!
The heating of the mold still takes a lot of time, since we are pretty much trying to heat up a block of aluminium with a small hot plate in a very cold room and it’s losing a lot of energy to it’s surroundings. But I already painted the outside last night and will work on insulating it next.
If you have any suggestions, let me know! Right now I’m thinking about a first try with a simple box around it and some glass wool inside.
And here are some more details on the parts of the mold!
so I added some insulation to the mold now by building a wooden box with glass wool inside and added a second heat plate to the top, to speed up the heating processes. Moreover I looked into alternative, maybe more sustainable, heating technologies and watched some videos on induction. (Check out this one of a induction mold: https://www.youtube.com/watch?v=K1-DKFBuSJM and this one just to be amazed: https://www.youtube.com/watch?v=JnWe_X20QhY)
Anyone having thoughts on this? Did anyone try to build induction heated molds yet?
Moreover I spend time on running test rows with the wheat bran material and it seems to get to a point where it’s getting quite fast: For the last test I did last night the pressing time was 2 minutes at a temperature of ca. 140° C
I added some pictures of the last tests, check them out below!
Still I was having some heavy thoughts last night, after I did a rough calculation on the costs / price of the bowl. So I have a question: How much more would you pay at a market / festival to eat out of a edible bowl, compared to a single use one?
And would you rather make the bowl yourself or get your food already served in it?
More thoughts on that will follow soon, but let me know what you think!
Hey Birls and Goys,
here are some quick updates on my insulation / heating problem:
Last week I CNC cut the second hot plate part for the mold and attached it onto the top part. Now the heat comes from both sides at the same time and it got much easier to work the mold in the process.
Moreover I build a more propper insulation which is directly connected to the two parts of the mold, so it keeps the heat, while emptying and refilling it.
To build it, I cut up a scrap piece of metal and mounted them to the parts with some screws. As insulation material I stuffed some stone wool in between.
So far it seems to work pretty well, heating it um to 140°C in about an hour and maintaining the heat in the process.
Let me know if you have any thoughts!
the bowls are 140mm in diameter and 45mm deep right now and the walls are 3mm thick.
The current size and shape came more from an experimental side of things though, since I wanted to test how evenly the material spreads under pressure.
And because I found 180mm aluminium disks on the scrap yard 😉
Wow that was a lucky find! Aluminium bar that size is expensive (I know, I’ve just bought some).
Yeah, I guess you are right! We paid 3 €/kg, which seemed like a good deal as well.
What are you using the aluminium bar for?
I must say there is a lot of R&D that has been in process to get the right end product. Do we have have any parameters in terms of how much pressure is right for forming a bowl from Wheat Bran?
Hi I did a similar kind of experiment but with starch and wood pulp fiber.managed to produce a foamed glass with good surface finish.but the main problem is it’s not waterproof.
Hey there, sorry for the late replies. Somehow my notifications stopped working😒
@niting85: We posted the settings we found most useful for our machine over here!
And @chintu: Wow, that surface looks super nice! Would you be down to share a little more about the process you are using? And how you are getting the starch to foam that well? I would be super interested!
We are starting to go into different surface finishes, coatings and imprignations right now and will share more about it as soon as we found good stuff! 💪
This is why it pays off to keep an open mind and. try to read the whole forum:
@chintu (PoC foam)
“managed to produce a foamed glass with good surface finish”
Come on dude, don’t leave us hanging, how did you do this!
Oh btw, induction heating…
That video is insane, lets watch that again in slooooow moooooooot
I am Viveak from India. I have tried to make biomass plates and cups from wheat bran and rice bran. I tried to make plates and cups with mold of initial temperature of 100 deg and added the bran to the mold and compressed , the problem I faced is the cup or plate is sticking to the mold and couldnt remove the material from the mold.The plates and cups breaks, it does not have suffient strength, for this I have tried with starch+ bran then also I couldnt remove the material from the mold. Please suggest me 1) what should I do for the material to be released with sticking 2) How can i improve the strength of the plates and cups
thanks for sharing your progress! 💪
To answer your question #1: There are a few factors that can influence the stickiness of the material to the mould. First off, what is your mould made from?
Can you post a photo of the mould as well?
The smoother the surface of the mould is, the less likely the materialy is to stick to it!
Second, the temperature you press at can play a big role in making it stick. Could you share a bit about your process (what temperature do you press at, how much pressure are you using, how long do you press for?) and maybe a photo of your press setup?
And last, you can use different oils or greases to make it easier to get the material out of the mould. We had good experiences with rice bran oil, since it has a high burning point and is still fairly cheap and available.
Hope I helped you a little already! And if you can put more information online, I’m sure we’ll figure it out! 🙂
Thank u for your suggestions
#1 The mold is made of Mild steel ( Cast steel)
#2 Regarding the temperature I dont have the facility to measure the temperature but approximately 90deg C
# 3 pressing by hand operated press it may be around 2 to 3 kg/cm2
The mold I have ordered is as in the latest pic pic. This is made of aluminum alloy casting,
please inform me what temperature and pressure should I maintain to achieve a good quality and good strength. As one of of friend said I am using a hydraulic car Jack to apply the pressure.
The temperature depends a lot on where and how you measure it, so it’s something you might have to try out a little. We measure in the heating element right now and pre-heat the mould for a while. And our favorite setting for the wheat bran is around 100°C.
Let use know, when you have the new mould and how it’s going with that! 🙂
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