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Large Injection Mold

This topic contains 4 replies, has 5 voices, and was last updated by  Tajdar Khan 1 year ago.

Edward edwardmartinhill

Large Injection Mold

07/05/2018 at 19:43

Hi team, I am looking to make a large injection mold (approx 300mm x 20mm x 20mm box and am looking for some advice on how to adapt the injection mold to fit.

I was considering a double injection i.e. 2 barrels, 1 hopper to avoid cooling of the plastic when it enters the mold. Has anyone had any experience with this technique?

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In reply to: Large Injection Mold

07/05/2018 at 21:20

On the finished part, where would your preferred sprue be? The best place in my mind would be in the middle of a 300x20mm side. I don’t think that there would be a need for a second nozzle with a block this size. If you’re worried about the plastic cooling too quickly, I would suggest heating the mold a bit before injection.

The double injection idea intrigues me, so I’ll be working on some preliminary ideas on this for a little while. My initial idea would be to keep the two nozzles as isolated systems, only linked by the handle. My thought on nozzle-to-mold connections would be flanges, but I’m not sure how well this would work out in practice. especially looking at fabrication costs these days.

I’ll post an update when I finish modeling one.

In reply to: Large Injection Mold

27/05/2019 at 20:34


What is it exactly you you are trying to make?

Just “the box” or is this just the box size of the mold?


I’m not an expert, but I do get a lot of information from the forum, so if I knew what you are looking for, I (or anyone watching) could better point you in the right direction.


An image or two might be very informative.

In reply to: Large Injection Mold

27/05/2019 at 19:59

Are you in Tanzania?

In reply to: Large Injection Mold

31/05/2019 at 07:46

Hello Edward,
Molding such a big piece would be a challange on hand molding. I would suggest using the compression machine. See the link https://preciousplastic.com/en/videos/build/compression.html .

But to answer the question, here are a few calculations (Assuming all in SI units).
Part Size = 300mm x 20mm x 20mm
Thickness = 3mm
Part Volume = 63 mm³
Part weight (PE) = 59 gm
That is alot of material to be pushed through a hand molding. and not to forget the amount of clamping force required.

If you want to go for the two gate system , woul would end up with a weld line in between the part. That would be a weak spot.

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