Pneumatic injection machine

I’ve been struggling trying to get consistent results injecting larger HDPE parts. Finally gave up trying longer handles and added a cylinder. I’m really happy with it.

I also modified the injection tube and made the plunger out of chrome plated shafting. Less friction on the plunger and it doesn’t get stuck in the tube anymore.

wow looks neat! You have a video or something? Would love to see it running

Here is a video of the machine in action.

Thanks, I’m going to build another machine, I think the Hoekens link will definitely be included.

Nice adaptation!


That cylinder looks to have a pretty long stroke, you could make the arm on that side longer to get more leverage and more pressure. To get around the problem of the plunger rod being pushed off vertical, you could use a Hoekens (not Hakkens!) linkage.

you could use a barrel with larger diameter and bigger band heaters now that you have automatic pressing action to achieve parts with larger volume. the machine looks great though

I’ll work on making a video.

With the cylinder and adding a valve to the injection tube it’s possible to pressurize the system and do multiple injections by threading on a mould, open the valve, close the valve, repeat. The cylinder keeps advancing the plunger for you.

Thanks for your hard work. The injection machine is simple, strong, easy to build and modify.