A Plastic Injection Machine You Can Use At Home

3D printing is all well and good if you want one of something, but if you want lots of plastic parts that are all largely identical, you should consider injection molding. You can pay someone to do this for you, or, in true hacker fashion, you can build an entire injection molding setup in your own garage, as [Action BOX] did.

The build relies on a pair of beefy 3hp motors to drive the screw-based injection system. These are responsible for feeding plastic pellets from a hopper and then melting them and filling the injection reservoir, before then forcing the hot plastic into the mold. Further stepper motors handle clamping the mold and then releasing it and ejecting the finished part. A Raspberry Pi handles the operation of the machine, and is configured with a custom Python program that is capable of proper cycle operation. At its peak, the machine can produce up to 4 parts per minute.

It’s an impressive piece of industrial-type hardware. If you want to produce a lot of plastic things in your own facility, a machine like this is very much the way to go. It’s not the first machine of its type we’ve seen, either! Video after the break. 

[Thanks to Phil for the tip!]

25 thoughts on “A Plastic Injection Machine You Can Use At Home

  1. I had an injection molding machine as a kid… a toy of course, but it ticked all the boxes. It was a heated vertical cylinder with a plunger, below that was a slot for a 2-piece plastic mold.The feedstock was a granulated rather waxy material. The procedure was, fill the chamber with measured amount of the granules and put the mold in the slot below. After allowing time for the plastic to melt, you pushed down the plunger to inject it into the mold. It really worked pretty well for a toy. I had molds for tanks and soldiers and construction equipment like bulldozers, and the plastic material in several colors. I wish I could remember what it was called.

      1. I had one of these. It went the way of many of my toys, but I found a replacement on eBay a few years ago. Unfortunately, the molds were warped to the point where they won’t work any more, so I’ll have to make some new molds in order to play with it. The molds were made of what looks like nylon, and the plastic that was injected I think was a blend of polypropylene and paraffin that melts at a pretty low temperature (similar to what is sometimes called “carving wax”), but still, using thermoplastic molds to mold thermoplastics is kind of iffy.

    1. I’ve been planning to make something like this. All the motors and other stuff seem unnecessarily complex, when all it needs to do is: 1) Melt the plastic 2) Make good seal with the mold 3) Apply a lot of force (i.e. my weight) over a few seconds.

      1. The key here is automation (well at least for as much of the process as can be practically done). Sure you could absolutely do everything the motors do manually but I have a feeling the goal for this specific project was automation.

  2. The really cool part is you can 3D print a pattern, make a plaster copy using a silicone mold and then cast zinc alloy dies after drying the plaster in the oven for 24 hours and achieve surface finish as good as the 3D print. Subject to details such as pulling a vacuum on the plaster to remove bubbles and other details.

    I’ve never understood why anyone would use a 3D printer for volume production.

    1. for low temp plastic and for resin 3D printers using high temp resin you can even just skip straight to 3D printing the molds with some kind of basic “standardized” mold frame made from metal.

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