"zero waste" key tag & buckle! Insert mould.
Here is our latest product made with the injection mold and the off cuts from our bag production here in Sri Lanka. Key tags made from Polypropylene. Mold by @leebaz.
We can only recommend the injection mold if you have access to somebody passionate with a cnc machine. It’s the best way to make nice looking products and if you feed the off cuts or you just cut PP sacks, you won’t even need a shredder.
Cheers from Sri Lanka,
Rice & Carry
Just added pics of the new buckle mould that came in. Finally buckles not from virgin plastic! Same as the key tag it’s an insert mould. It could make two buckles at atime but we did not file a channel to the second chamber yet. Few more pics are instagram @riceandcarry
Great idea. I love the impression – very clear and legible. I wish mine came out so well…
yeah, exactly. I wrote a little blog about it here: http://colombodesignstudio.com/insert-mould-zero-waste-recycling/
The limitation then becomes the size of the insert, obviously.
In this case we based it on a few factors, such as the size of a key ring and also a fin key I’ve got in mind, but also the size that my cnc can handle.
By splitting the mould across the pipe thread it means you can easily clean out the material at the mould entrance. We call those the ‘spinning tops’
It is just from my injection moulding experience, if the mould is too ‘cold’ for the hot plastic, there is a layer of plastic, that solidifies very fast when it comes in touch with a relatively cold mold and some surface features (like letters if they are smaller) can be left unfilled.
The way around it is to pre-heat the mould, so that it gives good parts straight away.
@jegor-m yeah – I thought we would need to too… but it doesn’t seem to be the case. However, there was an early blockage coming out of the injection pipe, but now we use a plumbing tap to seal it while the mould is emptied… seems to work pretty well.
One of the early lessons was getting enough venting! That seemed to make a big difference. We send @riceandcarry the mould prepped for venting, but they add it with a file until it’s enough… a bit of trial and error.
@jegor-m no need to preheat. What is crucial is good size vents and a big enough entrance. You don’t push plastic down into the mould, it’s more like you are pushing plastic through hardening plastic (if that makes any sense). So for example you have red plastic furthest down in the pipe and white flakes on top, your product will get red near the entrance to the mould and not at the bottom. So when the entrance to the mould is to small it blocks too easy. Luckily they are aluminium so pretty easy to modify. We use PP which seems to be easy to inject. I tried HDPE one time and that was more difficult in terms of fluidity.
@jegor-m as @leebaz mentioned it makes a big difference to use a plumbing tap to close of the pipe while you empty the mould. We tried to attach the last heating clamp as low as we could but the last bit of polymer that is exposed to air will never be ideal to inject. The plumbing tap will have a bit of hardened plastic attached to it that sort of fills the first bit of the pipe. So when you take of the tap you will have straight away ‘ideally’ heated polymer from 2cms up the pipe. Can make a big difference.
Hello! No, I have not posted my attempt. I re-melted it, actually 🙂 I’m still working with compression and striving for bubble free blanks. Once I get that worked out, I’ll go back to dealing with how to get my impression in the piece.
Here the pic of the plumbing tap. That bit of plastic pushes into the heating pipe so when you start working you don’t have the solidified bit of polymer at the end because it’s exposed to air or a not heated mould.
It just ended up coming off like this so if you get a tap like this no need to do anything really, just wait until it fills up like this and when you finished heating and you take it of it looks like this. We reattach it after every injection.
this is awesome! looks super clean, great detail on the debossing.
did you do any volumetric analysis of the object to figure out how much plastic to inject? or are you playing it by ear for now?
any issues with draft angles etc. to be able to remove the piece from the mould?
it’d be great to see photos of the piece out of the mould, before and after trimming!
keep up the great work.
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