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Plastic Plate Press, semi-DIY/semi-professional
- This topic has 96 replies, 36 voices, and was last updated 2 years ago by
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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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I finished the machine!
And the mould!
and today I’m pressing my first plate!!
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HI Guys,
I just wanted to showcase the latest results, after a redesign of the mould I have been able to produce Beautifull plates from PP(Blue) & HDPE(Black).
also watch the new and improved video!
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I quickly made a small movie for you guys:
I’ll make a better movie in the coming weeks
@richardtim
An update will be there soon,
I’m currently building the prototype,
for now just some foto’s:
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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.
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The first plate has been pressed!
750 x 1050 x 12 mm
2hr melting in a preheated oven 250 C
1hr cooling with fan blowing through press bed tubes, surrounding/room temperature 32 C
I only need some small mould improvements for better releasing.
And I’ll make a redesign on the machine before I’ll share it.
Let me know what you think I should improve/ think about/ …
I’ll keep you posted
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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
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@xxxolivierxxx , thx for the compliments!
In the mean time, I’ve made more progress!
But I lack the time to do a good update, so I’ll do a quick one:
I bought a Pizza oven! 650€ :(, but with inner dimensions of 120x90x30 😀
I bought a book press! 50€ 🙂 with pressing surface 50×50 🙂
I improved my process and mould design resulting in 99% solidity!
I added cooling blocks on both sides of the press, Hollow square pipes, this enforces even cooling resulting in very Good flatness!
The mould design is also improved with a cutoff edge, resulting in minimal fleshing!
See all in the pictures below. all plates are 500x500x12mm
As always feel free to contact me for more info
Or reply with comments, suggestions or questions.
In the coming weeks I’ll be designing and building the press for 1220x1220x12mm plates, I’ll report back with new results!
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OK, I chose to go forward with concept B, but I first wanted to proof that it would work. Luckily I tried it out because afterwards I came back to the decision. Now I want to continue with concept ‘C’, Which I tested again, which proved that it works quite well.
The most important insight was the simplicity of the process,
Rolling caused every thing to bend and move and it took too long.
While ‘cold’ pressing with a simple press after melting in an oven, is very simple in materials and process. A flatbed press exerts the pressure evenly over the entire surface and the pressing part of the process occurs quicker, resulting in better surface quality. See the pictures below.
The plan for now is to design a mould and press that are perfect for this process, pressing well defined plastic plates. The press and build plan will be designed in such a way that you can easily adjust it to the size you want or that fits the oven that you have or can acquire.
Next to that I’ll do a suggestion on how to build your own oven.
I’ll keep you updated!
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@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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Hi,
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.
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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 😅
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thx for the compliments
I changed the mould to steel because of the source-ability of the material, in some low resource settings aluminium is hard(er) to come by or very expensive.
Also, the mould needed additional strength and welding was the preferred joining technique.
next to that the scratch resistance of steel is better than aluminium which is nice when cleaning mould. And steel thus holds its polish for a longer time.
I’ve added some pages from my design documentation in which the mould design is discussed, evaluated and improved
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Hi I made another video of the machine building process
Would be nice If some of you could take a look at it and give me some feedback, just imagine that you also have the technical drawings. 🙂
https://www.youtube.com/watch?v=Vnq2DNYrgGE
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.
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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.
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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
Hi @nickchomey
Thx for your interest and eagerness! and sorry for my absence and brevity.
Next Friday I have to hand in my Thesis so I’m a bit preoccupied 😉
But I could post my entire thesis when it is finished, I think, I’ll have to check to be sure If I’m allowed, but I think I am since I wrote it.
But for now, I’ll copy paste some sections to answer your questions:
Force requirement:
Leonard S***g suggested this pressing-force requirement, to be at least 64 Ton or 640 kN for a surface area of 1.32m2, which translates to a pressure of about 0.5 MPa or 5 Bar (see appendix XX). For a plate of 1,22 x 1,22, this would mean that a pressing force of 720 kN or 72 Ton is needed, which is quite a lot.
The Plastic plate press system of Heat-MX uses a total of 64 Ton or 640 kN of pressing force, this only result in a pressure of 0,2 MPa or 2 bar. For a plate of 1,22 x 1,22, this would mean that a pressing force of 320 kN or 32 Ton is needed, which is already less than half of what Leonard suggested.
When calculating the pressure that is applied by the press setup used in the prototype tests (book press), the lowest pressure requirement is found. Only 0,175 MPa or 1,75 bar is applied according to the calculation found in Appendix XX. Although this is the lowest pressure requirement suggestion, the calculation is believed to more likely result in a higher pressure than the reality than a lower one. Most importantly, is the fact that this setup does result in plastic plates that satisfy the requirements.
Like most decisions in this design project, the easiest executable and most affordable solutions are tried first and only when tests provide indications that the design can benefit from added complexity, a new solution is sought after. Thus a pressure requirement of a minimum of 0,18 MPa is put in the POR. This results in a force actuator output requirement of at least 268 kN or 26,8 Ton.
Hydraulic jacks:
This choice was made because of the relative ease of instalment which allows the parts to be connected to it to stay as simple as possible. Also, the system seclusion of hydraulic cylinders results in a low need for maintenance and cleaning and the completeness of the cylinders ensure that no additional parts are needed besides the cylinders, opposed to for example a spindle, which needs custom fitting solutions for both the end nut as well as the guidance nut. All of these arguments combined also result in a lower cost price, which is also one of the primary decision drivers.
These benefit can however only be realised if the right cylinder can be found. The cylinder needs to fit the force requirements, the price range and needs to be source-able all around the world.
The minimum pressure requirement has been calculated in the previous chapter to be 1,8 bar which results in a force requirements of at least 268 kN for plates of 1.22 m by 1.22 m and a force requirements of 158 kN for plates of 1.10 m by 0.8 m, which is the size of the mould that is going to be prototyped.
Since the design goal is to be able to produce plates of 1220 x 1220 x 12 mm, the higher requirements are chosen to fulfil. This will allow for the prototype design to be scaled up without a need for other cylinders.
The price limit is difficult to decide upon, but as a first suggestion a fourth of the total allowable cost price is granted since the force actuator is 1 of the four main parts; $ 1200 / 4 = $ 300.
With these requirements in place, the search was set out. International websites were used to look for hydraulic cylinders, and soon it was found out that the most affordable cylinders are bottle jacks, which are often used in auto garages to lift up cars or press bearings in fittings. Also, longer bottle jacks were found that are used in engine hoists. In the analysis, it was also found that car parts or garage tools are an excellent source of materials since cars and garage tools are global common goods, and thus are good for the source-ability.
Press application
In the press, a stroke of 10-20 cm would be enough to provide access for placing the mould and pressing it shut since the current mould design will only be 45mm tall and when filled with plastic, will most likely not exceed a height of 10 cm. However, because of the cleaning access requirement as discussed in the previous chapter, it should be possible to move the press beds apart for at least 30cm. Other means than jack extension length can also realise this but, it would be very convenient if the cylinders could realise this feature.
The same holds for air pump option, which is demanded by the design requirements, but it is a very convenient option that adds to the usability of the product. Next to that, when it is chosen to use multiple jacks, the activation can be centralised by linking the pneumatics.
When it comes to force-output, single small jacks can be found that satisfy the needs, 30-ton jacks or 32-ton jacks would suffice and are available within the price range. However long ram jacks are not found for the required force output.
When considering these three arguments, logic would demand a single small jack of 30 or 32 ton, since only they satisfy all the requirements, although not the wishes. However, the other options only satisfy the wishes and not the force requirement or at least, not by themselves. When multiple jacks are used, also the long ram jacks can satisfy all the requirements. For example, when four 8-ton jacks are used, 32 tonnes of force can be realised.
The choice between a single powerful jack or multiple weaker jacks thus needs to be made. This consideration of multiple jacks may seem un-logical since four weaker jacks are more costly than a single, stronger, jack. However, there is a good reason to look into this option. The force distribution from 1 central point to a large surface area has different structural requirements than the force distribution from 2 or 4 points to a large surface area. Figure XX depicts two simplified situations in free-body diagrams (FBD) with corresponding shear force diagrams (SFD) and bending moment diagrams (BMD). The distributed force indicated with Wp represents the pressure that is put on the mould, FA represents the force generated by the single bottle jack of 32 tonnes, and FB & FC each represent two bottle jacks of 8 ton totalling to 16 ton each. This doubling is done because of the simplified 2D representation in which the 3rd dimension is compressed in a single layer.
In the diagrams can be seen that the maximum shear force and maximum bending moment can be significantly decreased by choosing multiple load points instead of a single centralised load. Keeping the maximum bending force as low as possible is essential in this design since bending deformations in the press-beds will result in thickness deviations in the plastic plates. These deviations may not exceed the defined tolerance requirement of +/- 1 mm, and thus the bending deformations may not exceed this limit. This can only be realised by integrating sufficient stiffness into the press beds and thus lower bending moments allow for less stiffness which allows for smaller beam profiles and less material. All of these consequences result in less material use, less complexity and lower costs which all are very much wanted.
Concluding
Four 8-ton long ram jacks with air pumps are chosen as force actuators as long as costs allow it. This choice is made based on the following arguments:
Multiple load points are beneficial to the design as opposed to a centralised load point. Extended ram jacks have a long stroke (more than 30 cm), which allows for easy cleaning access positioning. Air pumps allow the activation of the jacks to be centralised and by it, the jacks can be operated by a single person. Four jacks, each with a maximum lifting force of 8 tonnes, total to 32 tonnes of pressing force which satisfies the required 26,8 Tonnes 8-ton long ram jacks are commonly used in engine hoists, making them source-able almost anywhere on the globe Most of the available 8-ton long ram jacks have two single axle fixtures, each on one end of the device, making them very easy to install.
8-ton long ram jacks can be bought locally in the Netherlands for € 70,- per piece, totalling to € 280,- for four units, which is just below budget. Ordering form china, similar units can be bought for below $ 50,- per piece (alibabba.com).
Figure XX shows a picture of a typical 8-ton long ram jack with an air pump, more information about such a hydraulic jack is found in user and safety manuals such as the one by harbour freight:
https://manuals.harborfreight.com/manuals/94000-94999/94562.pdf
Fleshing, cut-off-edge & stopper:
In the mould frame iteration tests, subsequently, three frame edges were tested. The tests started with the most straightforward frame edge, a square section all around like depicted in figure XX-A. This test pointed out that the heating and pressing method functioned quite well, but the frame edge did not do an excellent job of cutting out the plate shape and defining the chosen plate thickness. The pressure build-up was insufficient, and thus the resulting plate ended up too thick, and the fleshing was not cut off, as can be seen in figure XX-M.
With the previous test in mind, a frame edge was fabricated that had a very small cut-off-edge, 2mm wide, while still providing enough strength and stiffness by having a fatter base, as can be seen in figure XX-B. This small cut-off-edge was theorised to build up more pressure since the contact area was decreased significantly. This theory proved to be true since the plate result that was outputted, was cut-out perfectly and the plate thickness turned out as planned, see figure XX-N. However, during fabrication of the frame edge, it was noted that it was much work with semi-advanced machinery to produce the specific section and therefore it would not be suitable for production in low-resource settings.
The third iteration was a simplification of the small cut-off-edge. The edge was integrated into the mould-tub, by only folding up a small edge that directly functioned as cut-off-edge, see figure XX-C and XX-F. When filling the mould with plastic flakes, a first problem arose; The granulate towers high above the small edge and is not properly contained and thereby falls out of the mould very quickly, see figure XX-I. When the plate was pressed, however, the mould seemed to do its job quite well. Only when the plate was finished cooling down, and it was taken out, the second problem showed itself; because the previously existing enclosing mould walls were now missing during the melting process, direct heat radiation burned the plastic, as can be seen in figure XX-L. Next to these two problems that disqualify this design solution, the edge itself did do a great job of cutting out the plate and defining the plate thickness as can be seen in figure XX-O.
Concluding, the small cut-off-edge concept has proven to do a great job of cutting out the plate and defining its thickness. However, the producibility should be improved to make it suitable for production in low-resource settings. This improvement will be realised in the embodiment design and will be tested in the large-scale prototype.
I hope you can make something of it without all the images and context, but for now this is all I can Provide 😅 Next week I can be more elaborate and we could even call/skype
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Awesome documentation @markbertbach, thanks for sharing back here! I’m following with joy 🙂
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
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@hadin & others
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 message 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.
Thx for the compliments!
AT the end of this month I have my graduation presentation, around which I’ll also discuss how the design is going to be shared and what will happen to the machine that I built. Afterwards, I’ll maybe join the precious plastic Army in Eindhoven to work on V4 and improve or make a new press design.
And I’m also looking around for a job 🙂
In the mould I place a frame with a special section profile, the edge limits the pressing hight and by making sure the last bit is only 1.5 mm width, the cutoff pressure builds up. this results in the very thin fleshing that you can just rip off, sometimes it even stays behind in the mould being completely cutoff.
this edge is bolted to the sheetmetal tub, the chamfer you see on the profile is there to leave room for the curved corner of the sheetmetal tub.
But for manufacturing simplicity I made a redesign which I’ll share later on
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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
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!
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?
thx for the kind words!
I’m happy to help,
also I’m starting my own business building presses, ovens and sheet-pressing tools and making sheets and products from sheets.
So when the time arrives I could build something for you or come over to do a build on site.
For the smaller size a single jack could work, I used a vice screw for 50×50 sheets
for 60×60 I’d say minimum of 6.5 ton
Hacking tools is of course really nice, but in this case, I think it would make the machine more complicated and more expensive. If the welding is a problem, then with some small adaptations, the machine can also be bolted together, that would even be better for critical load safety. But I limited the number of bolts because of their expensiveness and sourcing difficulties in low-resource areas. Welding gear is found almost anywhere.
And thx for the compliments on my welding, but this was actually only my second big welding project, and at the start of the project I couldn’t weld that well. So I guess anyone can learn by doing!! Just make sure to save the critical welds for last, then you have a lot of practice time 😀
Superb work !
Congratulations for all the work and for the video !
For the design, did you consider the use of the hydraulic tools from Trad4u, @olce had mentioned ?
I like hacking tools. Doing everything from A to Z is interesting, but we have to be really good at welding as you are !
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