Injection machine in Barcelona.
As we posted in the welcome section, at TallerEsfèrica we built an injection machine. In the gif you can see Aniol perpetually working with it!
We are still working on the molds, but so far we’ve finished the first one, which gives shape to the piece you see in the picture.
These are a few things we found out to be important. We are sure some of these have already been mentioned in the forum.
In our case, our projected parts had cavities and thin walls (not too thin actually, but they aren’t solid pieces), so we needed a stronger structure for the machine. We used 40×40 profiles so that the force we could do was bigger.
Although we can inject our parts, speed is an important factor at the time of injection (for the final properties of the injection part). With this machine speed isn’t as high as it should be, so we’ve thought of a few ways to add speed to the process.
One is to add a pneumatic ram. We haven’t tried it yet, as we found that you need a huge piston to get the right psi. Also, the whole point of these machines is to exist in a low scale production zone, and not be compared to normal production machines, so we discarded this option.
A second option we thought about was to use springs. Have them in tension when the piston is up, so that when you release them they exert the force you need and fast. We didn’t try it for similar reasons as the option of the pneumatic ram.
A third option, which would actually not offer than much speed, is to use an hydraulic car jack to press the piston. It would offer a steady force all over the process of injecting (about 2 tonnes for a car jack that costs 16€). There are also the mechanical car jacks that offer similar pressures for similar prices. The main disadvantage of the hydraulic option is the return of the piston, which would need an aid to get back to the initial position.
The mechanical jack sounds like an interesting option as it is moved manually both ways. An possibility would be to add a big wheel with weight to add speed to it, but again, we haven’t tried these options.
The process we found to give best results is to add the plastic bits once the machine is hot. Then press with the piston to compress these bits before they melt to remove the maximum air possible. Add more bits in case we want to fill up the cavity, press again and leave the piston at the lowest position the bits allow, having them as compressed as possible. If air is left inside, in between the plastic bits, we found problems to inject properly, leaving the mold nearly empty.
Once the bits are compressed and melting we block the nozzle so that no plastic escapes, and after a few minutes we inject.
We are using the Sestos D1S 220v PID controllers. They work fine, but aren’t super reliable with temperature control. We had to know the way they worked to adjust temperatures according to how they behave, not what they show on screen. They do the job perfectly for now, though. It helps to use a high temperature thermometer to know the actual temperature the machine is at.
Hope this helps!
Aniol and Marc from TallerEsfèrica.
Thanks for the feedback @talleresferica, really appreciatie that! Although our focus is keeping the machines as basic as possible we have also been exploring a more efficient way of scaling up production as well. We haven’t tried it, but aiming to do some test with air pressure. We’ve also used this before mechanism before which requires less force (used for childeren). But it doesn’t necessarily speed up the process yet. :
Hi Aniol and Marc,
It’s interesting reading your ideas: pneumatic, springs, car jack, flywheel etc. these ideas parallel my own.
Regarding the car jack, check out the tekca machine: https://www.youtube.com/watch?v=OfxEhQsTNB0
Congratulations on your machine and thank you for sharing the difficulties you’ve encountered. I’m quite interested in the parts you are making as I also intend to make parts with thin walls and somewhat more intricate features.
I really look forward to your future posts and photos 🙂
Hola Cyrille, que tal?
Awesome that you are starting this!
We savaged most of the parts from old stuff and old machines…Ask what it is that you can’t find and we will give you a hand if we can!
What project are you into?
Thanks for answering!
We are being pretty ambitious, since Dave was so kind to share blueprints for all the machines we are trying to build all four of them. Right now we are focusing on the injector because it doesn’t require any specific parts. However I’m having a hard time finding a seamless tube and a plug that fits it exactly. Did you buy it in a metal shop or did you salvage it from a machine?
Do you also have some good addresses for scrapyards where you found most of the materials you were looking for?
We didn’t go to any scrapyard, since we salvaged components from machines in a friend’s workshop. The seamless pipe was the only thing we bought, together with the electronics. Check Schröder, by Granollers. You will need a car since it is in the C17 road.
Hope this helps!
tienen foto de como conectaron la electronica, tengo dudas en cuanto al Relé.
We’ve been very busy building the machines in the last 2 months but I’m stuck on an issue for the injection pipe and extrusion barrel. How did you guys make the thread at the end of the pipe to connect plumbing connectors? Did you find the tools Dave Hakkens uses in the video? (I’ve found some places that had the tool but not for such big diameters). Or did you just use a lathe?
Sorry, we’ve just seen this. FOr some reason we don’t get notifications when someone writes here.
We based our machine on V1 and redesigned it to fit our needs. Not sure what tools you mean, but for the end of the cylinder where we plug the nozzle we used a lathe.
I guess you’ve solved this already, but hope this helps! We should meet soon!
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