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Plastic Plate Press, semi-DIY/semi-professional

This topic contains 96 replies, has 36 voices, and was last updated by  Phil Pickering 1 year ago.

Mark Bachrach markbertbach

Plastic Plate Press, semi-DIY/semi-professional

25/01/2018 at 12:23

Hi, I’m Mark, An Industrial Design Engineering student.
Currently, I’m working on my graduation project, the design of an Open-source plastic plate press for bottom-up recycling in low resource areas.

I’m planning on finishing v1 of my design before the end om May, this year, but a lot has to be done still.

in a few weeks I’ll start the real design work, and around the end of march I’ll start building a prototype.

But first I need to find out what people expect from such a machine, this is where your help comes in. If you are someone that would like to recycle plastic waste through use of a plate press, please help me and tell me what I need to know. To make it easy I made an online survey: https://mark171.typeform.com/to/yrgyP5

I’ll keep you posted on the results, developments and creations in future posts.

25/01/2018 at 12:23: Up til now I started collecting and small-scale experimentation with a panini iron.

07/03/2018 at 11:11: I’ve done a range of experiments, Gathered survey results from around the world, set a goal and now I’m doing actual design work. scroll further down this Topic to see what I’ve shared so far and feel free to comment, all help is very welcome.

03/12/2018 at 18:42:

since today, all of my documentation is publically available here

I did this project for and together with the MMID Foundation so make sure to attribute to them and me if you do any publications, as it says in the Creative Commons Attribution 4.0

This nicely rounds off this project and since I am now working on the sheet-press at V4, still sponsored by the MMID Foundation, I’ve started a new Topic to keep you posted on all developments.

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25/01/2018 at 12:38

haha good start! 💪

25/01/2018 at 12:41

I’ll keep an eye out for how you progress with this. Best of luck with it. This would work for my chair design. I am trying to see if it is possible to make fairly large plastic sheets to use for side cladding.

25/01/2018 at 13:03

Actually the panini grill works great, very nice and smooth results, without even shredding. Now I only need to scale it up and make it easier to use and build.

25/01/2018 at 13:16


Hi Mark. Quite thorough survey you’ve got there. But that is good. Please also make sure to search related topics on the forum as there are a couple of people who approached sheet press building before.

Also, just curious, what type of plastic you’ve got there in a fresh panini?

25/01/2018 at 13:30

Thx for your suggestions Jegor-m,

I know my survey is quite thorough, but I think I really need to know that much :). Do you think it is too much to ask? then maybe I’ll change it, better more responses with less info than no responses at all 😛

In my last post the greenish plaque is made of SPA bottle caps, I think HDPE, it didn’t say

The second one, black and white is a set of PP prototypes

The third one, mixed color, is a bunch of HDPE and maybe some LDPE bottle caps, I think the brownish edges are toasted LDPE

25/01/2018 at 15:41

HI @marbertbach

I have just joined this community but a plastic plate press is something I would definitely use for the ideas I have in mind! I will try to fill in your survey!
Keep up the good work!

25/01/2018 at 15:49

Thank you very much! Please let me know if you have any comments on the form of survey.

29/01/2018 at 18:14

I’m still hoping for some more respondents: If you are someone that would like to recycle plastic waste through use of a plate press, please help me and tell me what I need to know. To make it easy I made an online survey: https://mark171.typeform.com/to/yrgyP5

29/01/2018 at 22:29

great start, Mark. I’ll fill out your questionnaire later.
I’ve been thinking off the same machine but don’t have allot of spare time for development.
I figured that using the back bench of a car or van could work well as hinging mechanism as its large and almost folds down flat. these benches are readily available across the globe.
just thought to put this idea out there.

31/01/2018 at 11:09

Thx brasem, that sounds like a great idea, I’ll definitely look into that.

31/01/2018 at 12:19

Yesterday I did a new test, this time with a mould that fits my panini iron.
The use of the mould creates a nice and defined plate, with predictable dimensions, which is really nice, however, without shredding, lots of air stays trapped in. And HDPE shrinks a lot, I actually knew that already, but still it surprised me.
Time to shred! and time to better control the temperatures!, I think.
I’m also thinking about drilling really small holes in the top part of the mould to let the air out.

01/02/2018 at 19:16


18/02/2018 at 09:10

Hi @markbertbach.

I want to know if after the plastics being melt, how did you cool down the temperature ? Thank You.

19/02/2018 at 10:34

Hi @krissa ,

The last test I did, was with an aluminium mould. For cooling I supported the mould on a piece of wood and left the weight (25kg) on top, this stack I put in front of the big ventilation wall in a spray booth while I left the door slightly open.
This caused an air stream to constantly pass the mould and since aluminium is very good at conducting heat, this cooled quite fast.
However, I want to reduce the mould weight (now it was quite heavy, thus absorbing lots of heat) and the production time, while scaling up to 1300mm x 1300mm x 5mm.
So I’ll be looking into other processes and techniques.
In this last test the plate dimensions where 20mm x 30mm x 6mm

19/02/2018 at 18:11

Hi All,

I processed the survey results and made some nice diagrams.
The survey is still open but I’m going to continue with the information I’ve gathered so far.
Whenever you see ‘FdeS’ or a Small circle with a black outline in the diagrams, that means that my subject context gave that value as an answer.

From the graphs I derive what kind of plate my plate press will have to be able to produce. But also how much power it may draw, next to that the results will be a reference for others that make an adaptation to my design.

Hope you like the results and the graphics!

For reference, this was the survey: https://mark171.typeform.com/to/yrgyP5

28/02/2018 at 12:27

For two months I’ve been collecting plastic waste and last week I got around to shredding my collection of HDPE (ca.10kg) , PP (ca. 6 kg) and PS(ca. 1.5kg).

Now the plate press tests with shredded plastic have started. I assembled my mould to produce 5mm thick plates and did so for HDPE, PP & PS as you can see in the pictures.

It was hard to get the right thickness since excess material couldn’t really go anywhere, thus it came up to weighing, which in my experience is not very precise, probably because of varying densities.

The results however are quite good!

Only a few and small air bubbles got trapped, the surface quality was really smooth and they are pretty straight.

the process is as follows:
– Weighing out the plastic
– Put it in de mould and close the mould
– Put the mould in the panini grill and set to max (250 C)
– Put the weight (25kg) on top
– Wait 20 minutes
– take out the mould and weight and let it cool outside (4 C) with the weight directly on top of the mould
– Wait 1 hour
– pry open the mould and retrieve the plate

PS failed the first time as you can see in the pictures. As a solution, I doubled the melting time to 40 minutes and that did the trick, I think PS has a lower flow rate and needs longer to distribute evenly.

The Blue/black speckled plate in the pictures is PP
The grey and random colour speckled plate in the pictures is HDPE
The Black with white and green speckles in the pictures is PS

28/02/2018 at 15:38

Since some people indicated that thicker plastic plates would be nice to have and useful for making for example furniture, I decided to test if this would work as well.

With the same set up only 3 times longer melting time and also longer cooling times I produced 3 plastic plates of 20 mm, again PP, HDPE and PS.

I also drilled holes in the mould just above the 20mm line, so air and excess plastic have a way to leave the mould.

The PS plate I gave 2 hours to melt and spread.

A new problem that arose, was the mould height, the shredded plastic takes up 2-3 times as much space as the solid end-result, so it would barely fit in my mould.

Next to this problem, the volume estimations based on weight and density were even less precise.And of course air getting trapped inside the plaques of plastic take up larger portions. For HDPE and PP this meant big bubbles of air getting incapsulated and together with the off volume estimations, the overall thickness was off by up to 7mm.

The PP plaque turned out completely skewed, one side being 21mm and the other 27.
The HDPE had the biggest problems with incapsulated air and its overall thickness turned out to be 27mm, not skewed. Also HDPE had huge sink marks, probably due to its high shrink ratio.
The PS plaque turned out very nicely, not so much air trapped inside, nicely solid and flat.

My theory is that the slower flow rate of PS causes air flow paths to stay open for longer, while the relatively fluid PP and HDPE close of the mould openings before the air can get out.

In the smaller plates (5mm) that I created before, I put the material in a mount in the middle of the mould, this way during the pressing process al the material flowed outwards pushing the air along. With the thicker plaques I had to spread all the material since it wouldn’t fit otherwise.

I think more pressure could really help to make the incapsulated air bubbles smaller or nonexistent, 25 kg on 0,06 m2 is only 4166 Pa (0,04 bar), this should probably be closer to 5MPa (5 bar), 125 times as much 😅

28/02/2018 at 15:51

I’ve discussed the survey results and conclusions with my case study context, Fábrica De Sabão in Angola. They really stressed that they need thicker plates for making furniture, 12mm would be great.

So the goal of my project is to design a machine that produces plastic plates/sheets of 1.220m x 1.220m x 5-12mm the thickness should thus be adjustable in use or per mould.

Thus scaling up the surface area is the next step
But first I’ll try to produce 12mm thick plates

28/02/2018 at 16:14

I produced two 12 mm thick plates, PP and HDPE, I ran out of PS 😩.

Everything went quite well and but again the HDPE plaque contains lots of big air bubbles.

The PP plaque turned out really well, only a few small air bubbles, good flatness, even thickness.

But It seems like the thicker the plates, the more difficult the process.

28/02/2018 at 23:01

Awesome documentation @markbertbach, thanks for sharing back here! I’m following with joy 🙂

01/03/2018 at 10:14

Thx! good to hear! I’ll keep on sharing and always feel free to give your honest opinion or suggest improvements, next steps, have-you-thought-about’s, etc…

01/03/2018 at 11:25

Wow, good documentation, keep the good work up 🙂

02/03/2018 at 11:25

@markbertbach Maybe to solve the air bubble issue put two different size flakes the smaller ones to take up the space.
Another idea would be to heat for longer with more pressure
Just thought I would put that out there

02/03/2018 at 15:35

@plastikfantastik thx for the suggestions!
Just now I tried melting with an open mould, so no pressure. I thought the air would be able to leave the granulate and mould this way. Then when it is one nice blob of plastic, I’d press it in its shape. It seemed to work, but sadly it didn’t. my next step will be to increase the pressure, using glue clamps.

And thx a lot for the link, that is really helpful!

I melted without the top half of the mould, but I did melt from 2 side, maybe that is why air got trapped still.

I’ll also try to melt from 1 side

02/03/2018 at 21:35

I think one way to get rid of air bubbles is not to use flakes, but pellets, means extruded and cut to small pellets.
Otherwise i am still thinking of a kind of laminator, think pastamachine.
BTW: Thousand Thanks for that extremely instructive and serious topic.

02/03/2018 at 22:14


nice idea for device!

Could you share this picture from survey in good quality, I just wonna print it out as a poster for my lab.

04/03/2018 at 05:45

@copypastestd me too!! it’s a great poster

04/03/2018 at 11:40

Hi @markbertbach !

Really nice work you did there, I also really like the outcome of the survey, even though there were not soo many people participating. Since we’re in the process of building a plate press too, I’m very interested in this. Keep us updated!

All the best

05/03/2018 at 11:17

@copypastestd & @plastikfantastik
Here is a Vector PDF of my Commodity plastic practical info poster. If you open it with Adobe illustrator you can edit the vector still, Otherwise just open as PDF and print.

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