- 20 Ton press for injection molding machine
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Re: 20 Ton press for injection molding machine
Before buying my larger machine, I was thinking about modifying the medium machinery machine I had. I'm still wondering if it would have worked. I think there are two possible opions: Making it manually operated like the one seen
at the end of this video:
. This would give you a much higher injection speed but you would loose a lot of injection pressure. It might also possible to somehow make a semi manual machine, where
you start the injection process manually and just use the ram to pack the mold once it is full.
Another option that I was thinking about was to pre-load a huge spring (think car suspension) that will store a lot of energy that could then be used to power the injection ram. I'm just not sure how you would control injection speed etc. and having
a lot of energy stored in a big spring can be dangerous. Still like the idea though....
BTW, it is a whole lot easier to inject HDPE or PP than ABS / PC-ABS. HDPE has usually a higher mold flow index but I'm not sure if it would be suited for your part.
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Re: 20 Ton press for injection molding machine
To be honest, financially speaking it would probably be better to just buy a small molder or mill the knobs/out source them. If you are doing it as a hobby it is of course an entirely different story. ABS is usually injected with 4500-15000 psi. If you know the projected area of your part (including runners etc.), you can now calculate how much force you need to keep your mold clamped shut. But as I said earlier... your main issue will be speed. Smaller parts like your knob are usually injected within 1-2 seconds, a hydraulic car jack is just not nearly fast enough. Check youtube, there's a bunch of small molders that use air cylinders which are much faster but usually aren't too strong.
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Re: 20 Ton press for injection molding machine
The volume is not really important. The projected area is what matters. Post some pictures if you get it working, I'm curious how it will turn out :-)
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Re: 20 Ton press for injection molding machine
Projected area is different than volume?
I do have a learning curve.
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Re: 20 Ton press for injection molding machine
You mean surface area.
I think that is the difference from the total volume to the outside shell.?
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Re: 20 Ton press for injection molding machine
yes it is different from volume and also different from surface area. The projected area is the area of the shadow that part (including runners) would cause when lit with a lamp. Multiply it with your injection pressure and you have an estimate of the required clamping force you need to keep the mold shut.
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Re: 20 Ton press for injection molding machine
The normal for clamp pressure/Tonnage needed is 3 to 5 Ton per square Inch this is the normal requirement,and yes surface area of the molded part, any surface area that will be affected by the injected Plastic, is to be calculated, to know what clamp pressure is needed, for a Hobby molding like you are doing, if you, inject the plastic into the mold, and you get flash, between the 2 mold faces, then you either need more clamp or less injection pressure, hard to control on a Hobby machine
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- 20 Ton press for injection molding machine
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