Hi Leonardo, Unless you are going to be making thousands of these, I would buy or have PVC extruded into the shape profile and then weld the PVC together into that rectangular shape. You could injection mold that part but it will require a large press. You won't be making one of those as it is not economical. There are presses out there that can easily mold parts that large. Years ago I was at an industrial auction and they were selling injection molding presses that were used to mold childrens play cars. The kind where the kid climbs into the car. The play "cars" are about 4 feet long. Anyway the company had several large presses and they were being auctioned. I wasn't interested in the presses but I was interested in how much they would sell for. The selling price started at $1000 or so and none of them sold. The issue was the size and weight of the presses. When the original presses were purchased they were brought to the facility via rail car. The presses could not be easily broken down into a size that could fit onto a semi trailer. The mold platens were about 6 feet square. Consequently there was no economical way to get the presses out of the building so they didn't even sell, which was way below their scrap value. They didn't sell as scrap since it would cost more to cut them up then they were worth. Plus the machines were inside a building so the use of cutting torches would be a liability problem.
If you want to make a lot of these parts, I advise you to find a large plastic injection molding company and show them your part and ask them how much it would cost to make _x_ number of parts. If they have a press that can handle the size, they will tell you. Having molds made is routine for those companies, so they should be able to give you prices for everything. I'm in the Midwest USA and this area has many injection molding companies. Ohio, Indiana, and lower Michigan have many large injection molding companies and plants. Dave On 10/15/2016 8:12 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! > > > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, SlashDot.org! http://sdm.link/slashdot > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
