But we had a different goal and used a different machine to accomplish that goal.
Our goal was to create a lunch box using the injection machine. The idea is that people bring their own used plastics to someone with the machine and the lunch box mould who can then make a personalized lunch box for them.
The cool thing is that every lunch box will have unique characteristics (material and colours). The thought is that the owner of the lunch box could proudly show others how precious used plastics can be and trigger others to create a lunch box of their own.
In the following video, the idea and vision are explained (password: preciousplastics): video
We managed to get to a point that we could actually create a small scaled box made out of PP, but with some more time and effort, we believe that an actual lunch box can be created. The biggest pitfall is in creating a mould, which takes a lot of time and requires skills and proper tools.
In the following video, a summary of the production process is shown (password: preciousplastics): video
Also thanks for sharing this here! Nice to see the process you made in mold making! To bad there was so little time, would have love to use your fully working lunch box!
Lots of people here are talking about how, in industry, the normal way to make a mould is to CNC a block of aluminium but how CNC machines aren’t that commonplace especially in the third world.
Norbert Heinz has an ongoing project aiming to provide education in machine building using everyday materials and simple tools. His CNC Machine V3 has a lot of potential and could me the answer to mould making problems.
I have no experience in injection or extrusion but do have experience in commercial vacuum forming. Look into heating a plastic sheet in the top of oven then when sagging, take out and place over mold and turn on vacuum. There are several videos on internet that show how to build and use a vacuum mold. Should be able to create a full size lunchbox suitable for our fat American kids. Good Luck.
of course, I naively assumed that the “new” plastic would melt right away when entering the mold… would it be possible to do a “to stroke” injection? or does the already injected plastic become solid to fast?
Indeed @redgurrillia Bigger lever means more pressure means you can create bigger molds. That said, there is a limit to the amount of plastic you can inject at once. Based on the heated plastic that is inside the barrel.
i believe this almost has to be for the injection machine (it has a shaft that is used to insert the plastic, not needed when you use the compression machine.
I believe that the size problem would not occur, or at least would not be so prevailent when you use the compression machine, because one can create a much higher pressure… but that should also mean that simply increasing the length of the lever on the injection machine (and thus the leverage) would make it possible to use bigger molds…
