Automatic injection moulding machine
There’s been some talk about this on other threads so I thought I’d post about my machine here.
I actually built this last year but have have kind of abandoned it now and gone back to using manual injection machines as I never got this working properly. The idea was, because mass produced ‘useful’ (not designer/arty) plastic items are so cheap, it’s pointless making them with a manual machine unless you’re prepared to work for next to nothing. Also there are concerns about breathing in plastic fumes long term, so I thought it would be nice to have a machine I could just fill with plastic, press a button, then come back hours later and find hundreds of parts made for me with zero effort.
Unfortunately I couldn’t get it to run fast or reliably enough for it to work the way I wanted, It can only make small items, I couldn’t think of that many items I would ever need thousands of, and swapping out the moulds and setting it up to work correctly was a lot more time consuming than with a manual machine.
But if you bought a shredder axle from me on the Bazar, it probably came in a tube with end caps made on this machine (value €0.02 each).
awesome work ! i just started the ABC about this,
https://www.youtube.com/watch?v=zVta87A2qsQ&frags=wn&ab_channel=THATLAZYMACHINIST and I am a little lost what to use, servos, steppers, pneumatic or hydraulic… see you in a year or so 😉
Hey fellas, i have recently join the precious plastic group and am really exited about it. I have been going along several threads and this one really caught my attention. I am hoping to build one my self one day. UNFORTUNATELY I dont have a workshop where I can build one BUT what I have and can offer is a lot of knowledge about Plastics (Technically known as Polymers), Molds and molding machines. I hope i can be of some help.
I would first ackwnowledge the work @andy has put into the machine. I like the two stage injection unit. The concept from @andy is awsome and practical (because its already done, checkout http://www.babyplast.com/ ). There are some things Andy could do to make it run smoother and probablly automatically (fingers crossed). I would be glad to help.
it looks similar to the Many Maker machine that was on kickstarter a couple years ago. I was eagerly awaiting it but the South African developer seems to have gotten distracted on other things and is unresponsive to emails.
If anything you could also just add in 2 pneumatic cylinders and automate it with arduino. I was checking the prices and they are really cheap on Ali Express
Hello All. This is quite an interesting topic and body of work. Congrats to all for your hard work. I myself also built a semi-automatic injection molder in 2016 with compressed air. I tried to use lower cost components. I have built many machines in the past and this is quite a difficult task…one that a person will be hard pressed to share freely. Here is my version.
The precision required to make this work is way beyond anything one could create in their garage and machine building knowledge and experience of many many years.
@btmetz I saw the ManyMaker in 2016 as well and was quite disappointed. Maybe others are as well? These machines will be challenging to set-up and tweak to get acceptable parts. They likely will not be able to produce medium to highly complex parts. Tianyuan Testing makes a machine very similar to these but with greater precision. Honestly it is a quite simple injection machine. Their cost was $8000 plus $3000 to be delivered to the USA.
Quite high price. Maybe because it is a low volume produced machine?
What if we have a semi automatic machine?
Similar to the old punch press machines?
2 pneumatic cylinders, and a cheap controller. One cylinder to inject the plastic, the other to operate the clamp. De-molding by hand. Maybe 2 or 3 man operation with multiple molds?
Don’t underestimate the clamping force required, even a large pneumatic cylinder will only work for small parts at low pressure. My clamp had a force of up to 5 tonnes and with a 50mm dia. mould cavity it would force it slightly open. A toggle or screw clamp is probably the best low-tech solution, and keep the frame and clamp structure short, mine is too long and has too much stretch under load.
I’ve been busy working on other stuff so my machine has just sat idle for probably a year now. The aim was to make it fully automatic so it can run unattended for hours on end, but it only takes one small problem (out of hundreds of potential ones) to thwart it. I might come back to it one day, it would be nice to get it working properly, or I might just dismantle it and build something else out of the parts.
Yup it takes lots of strength to resist the forces required. Lots of precision as well. Actually the controls are the easy part if you take out all of the safeties that are required by OSHA. Morgan industries makes a semi-automatic unit as you mentioned. $26000 new. Approximately $12500 new. https://www.morganindustriesinc.com/medical-applications/
Also the amount of force that is required is 3-5 tons per square inch. So 9-15 tons of clamping force would be required for your application listed above of the 50mm diameter cap.
Holy moly @andyn.. this is an epic build! It looks like quite an undertaking to down scale and build an industrial injection machine. Very impressed with the result. Props!
Interesting to see that you’re back to using the manual injector.. that unless you’re producing thousands of parts, its still faster to use and swap out moulds manually.
Very impressive! I wonder if the next PP injection machine could at least be half-automatic, resulting in faster production rates, so that it could have some business potential.
I’ve been thinking about making my own automatic injection moulding machine. There is a Russian guy who made a small injector that is fully autonomous and has a fairly decent speed: https://www.youtube.com/watch?v=VPq66NtLSt8
I really like Andrey Korotkov’s design. It’s smaller and much simpler, just a ballscrew to close the clamp, no injection piston, a screw just ‘extrudes’ into the mould. It seems to work very reliably though is only capable of making parts with small cross sectional area (I wish I knew what all the parts he makes actually are, I struggle for ideas of good things to make at this scale). The whole thing is driven by just 2 stepper motors.
That’s actually a pretty good idea and one that was right under my nose. It wouldn’t take much to modify one of my piranhaclamp moulds to work with my existing machine, just needs the sprue moving and some extractor pins added, I’ll also need to find a way to make the part reliably stay in the moving half of the mould so it can be automatically ejected.
As for making my fins, I need a good mix of the plastic, I really like the idea of having a screw that would pre-mix and bring the plastic directly into the injection chamber.
I might consider making something similar, but with less automation probably (I am not really confortable building automation system). I have a question : how the “extrusion” barrel is connected to the injection chamber ?
@lagrenouille It’s a ‘two-stage’ injection. The screw forces the plastic through a non-return valve into another cylinder with a piston. When this cylinder is full (detected by a sensor) the piston injects it into the mould. The advantage is I can easily change the piston for a different diameter to get different injection pressures and volumes.
@andyn, could you upload the firmware somewhere ? we’d like to make a smaller unit and it would definitely help to see how you managed to all the timing and sensors up and running 🙂 otherwise, no biggy 🙂
@andyn, i guess rather not; thanks so far 🙂
Hi Stan, Interesting question. I didn’t actually try a wood auger, so I can’t compare. Yes I think it would work, though it may take longer to fill the cylinder, I imagine a longer auger would be more effective than a short one (at least 20:1 L/D).
The motor I’m using is quite small, 180W I think, It has no problem turning the compression screw, but I noticed when using a smaller piston in the injection cylinder (less cross sectional area) that it’s a lot slower to fill as it’s harder for the pressure of the plastic to push it back. (I can change the piston without changing the cylinder, just the screw-in bushing the piston fits through, the piston doesn’t touch the walls of the cylinder at all)
I’ve kind of given up with this iteration of the machine and am currently building a simpler one, no 2-stage injection and no screw at all, just a piston pneumatically driven, and a stronger clamp!
You must be logged in to reply to this topic.