Thanks to all for your answers!

I'll try to answer in one reply so I don't make a mess with the

I've thought about pouring it as Marcus suggested but as you've said and
from what I was reading on forums and so, it's quite difficult in my case
because of the shape and lenght of my parts.

Welding the strips as Linden,Erik, and Craig pointed out together was my
first option, because I can polish the joints and that's it. But I found
the costs here in my country are way high doing it that way. Remember that
what I need to do with this rectangular shape is to thermoform it. Also, I
couldn't find sheets of more than 6 mm of thickness.

I came across with the idea of injection molding because it's a lot cheaper
than buying and welding the sheets. Another approach would be to extrude
the sheets and weld them but that would imply a lot of work in the
production stage. With injection I only have the head aches now, but if I
can make it possible it would be a lot simpler once it's ready.

Also please notice that the picture is an aproximation of the shape I need
to make the thermoforming, the final one is going to be wider on the sides.

Another idea that comes to my mind but I don't know how doable it could be,
is to have like an extruder than can make the turn and make the bend in the
sides to produce the rectangle with rounded corners (I don't mind about
that if I can cut them later), and then weld the last corner of the
rectangle. If possible I guess it could be a lot simpler that the injection
and I can save the costs.

2016-10-15 22:29 GMT-03:00 craig <>:

> On 10/15/2016 5:12 PM, Leonardo Marsaglia wrote:
> > Hello to all.
> >
> > I'm sure here I'm going to find good answers so I decided to start from
> > here.
> >
> > I'm planning to do some thermoforming production work but the sheet
> plastic
> > I need to use is rectangular with a rectangular hole in the middle (I
> > attached a picture so you can see). So to use regular PVC sheet would
> imply
> > a lot of waste.
> >
> > I came up with the idea of injecting the PVC using a manual clamped mould
> > and injecting it with a screw driven piston. The difficult part comes
> here,
> > I need to inject almost 3 kg of PVC. The moulds are going to be pretty
> > simple as you can see but I would like to know if there's any good source
> > to determine the approximate power I would need to drive the screw that
> > moves the piston.
> >
> > There's the possibility of using two pistons one on each side to make
> > things easier. Off course I would need to reduce the motors with worm and
> > gear and then connect the gear to the screw that drives the piston. But
> my
> > main concern is if this approach is correct or if I should forget about
> it.
> >
> > I didn't even consider the hydraulic pump because the cost would be a
> lot.
> > Also take into account that I'm not intending to make lots of these
> > injections per hour, so injection times could be slower than the industry
> > standard.
> >
> > I hope I've been clear about my doubts and I would be thankful if you can
> > point me to any source of info about this, or help me to be more sure
> about
> > the dimensions of what I need to do.
> >
> > Thanks as always!
> >
> I would expect that the temperature  of both the material and the mold
> will be important for the long thin shapes.  The viscosity will change
> as the material cools running down long thin paths.
>   It might be easier to extrude of cut the sides and heat bond them or
> mold just the corner to bond the pieces.
> craig
> >
> >
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*Leonardo Marsaglia*.
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