In this Instructable I will document the process of an experiment i have been working on to test fairly low pressure injection molding using 3d printed molds.
You should be able to find everything you need for this project laying around your house:
-An initial concept and the ability to execute it in a digital format capable of exporting to a 3d printer
-a high res 3d printer
-an injection molder
-a handful of pelletized thermoplastic
You should be able to find everything you need for this project laying around your house:
-An initial concept and the ability to execute it in a digital format capable of exporting to a 3d printer
-a high res 3d printer
-an injection molder
-a handful of pelletized thermoplastic
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Signing UpStep 1: Part design
My teeny, tiny, cute, little injection molder is only capable of squirting out about 1/4 ounce of molten plastic at a time so i had to design a test part no larger than that. I was far more concerned with testing the process than actually making something useful so i just grabbed an existing 3-d file of my logo and converted it to a moldable form.
I used solidworks to extruded the shape in two directions with 7 degrees of draft on both sides from the parting line.
the final part came in at a volume of 0.238268398 ounces.
I used solidworks to extruded the shape in two directions with 7 degrees of draft on both sides from the parting line.
the final part came in at a volume of 0.238268398 ounces.
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the process layering of 3d printing + molding has a lot of promise
case in point, this amazing pneumatic robot tentacle
http://har.ms/blog/print-your-own-robot-part-7/
I could imagine a small machine shop with a setup like this might have a mold for producing the odd part that is needed in small quantities, with a freshly RP'd mold ready to replace it if several orders come in a row.
Thanks for sharing your results. Now I am even more anxious to get an injection molder!
I've gotten a lot of criticism and questioning about why i wouldn't just 3d print all the parts in the first place.
There are countless businesses that require small volume high quality parts with finish and material options that just aren't available in 3-d printing and this solution could be incredibly useful in those situations.
You could integrate relief passes into your mold. I am attaching photos of a similar epoxy mold, where plastic is allowed to pour from the sides before building up pressure.
This way you could produce parts without stressing the plastic mold, and trim off excess material to get a finished part. For the box, you could make your mold round and fit it inside sections of cut up pipe.
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Levon Fiore @ Medium Machinery LLC, see our
Small Manual Benchtop Plastic Injection Molding Machine
I think my part was little too big so i had to use every last bit of possible shot so i was doing a lot of tricky things to get as much material as possible in to the mold which meant that some times i ended up getting a little too much.
I think with a little more experimentation and adjustments in my part size i could get good repeatability.
The main advantage of injection molds over 3D prints is speed, right?
all depends on the requirements of the individual project.
also, i could buy quite a few injection molders for the cost of my 3-d printer.
ebay, a manufacturing equipment vendor, equipment auctions, the internet.
the injection molder in my garage cost me about $500. There are options for both printers and molders that fall everywhere in between and some that go even higher.
What make/model of manual injection molder do you use?
This is a great idea BTW. With some molding experience backing you the ideas are limitless.
I have made tons of molds and I can tell you AIR IS YOUR WORST ENEMY!
http://www.youtube.com/watch?v=ZvC5BjhOb-A
I used the term "low pressure" because i am using a small manual injection molder rather than an industrial machine capable of 100's of tons of clamping and injection force.