All of the PVC Pipe I have seen has been extruded. PEX pipe is also extruded. I'm sure that black poly pipe/tubing used for sprinkler systems is also extruded. Plastic extrusions are very common because it is a very cheap way to make a profile plastic product, once the machine is setup. But its a continuous process....
Google "PVC Pipe Extrusion" and you will see some machines and videos. Here is a big one: https://www.youtube.com/watch?v=zcBv_JvFDBI If it was wavy then they were probably having quality issues. The OD is the critical thing with PVC pipe that uses glued socket fittings. Schedule 80 is only a little heavier than schedule 40 in smaller diameters. I've done work on extruders and plastics equipment controls. Molding by spinning is frequently called rotomolding or rotary molding. Many plastic Kayaks are rotomolded as are a lot of larger plastic tanks. Dave On 10/20/2016 8:00 AM, Todd Zuercher wrote: > Is schedule 40 (or 80) extruded? I don't think most of what I've used is. > While the outside is smooth the inner surface is usually a little wavy and > irregular, like it may have been spun in a mold??? > > ----- Original Message ----- > From: "Dave Cole" <linuxcncro...@gmail.com> > To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> > Sent: Wednesday, October 19, 2016 11:49:08 PM > Subject: Re: [Emc-users] Wat OT: Question about injection molding of PVC > > Ive never seen it poured. However think of all of the things that are > extruded out of PVC in high volume. > PVC pipe, gutter, fence posts, window frames, vinyl siding and trim. > The trick will probably be finding a place that extrudes PVC in small > quantities. Most of the plastic pipe plants around here have silos > outside of the plant full of PVC resin pellets ready to be fed into an > extruder. Some of these silos are 30-50 feet tall. The high volume > plants usually have a pneumatic conveying system to deliver the PVC > pellets to the extruders. Once they start up an extruder it typically > runs 24x7 until they are done with that run. > > Dave > > On 10/19/2016 4:46 PM, Leonardo Marsaglia wrote: >> 2016-10-17 9:50 GMT-03:00 craig <cr...@facework.com>: >> >>> I don;t know what resources you have there. >>> >>> Minimum equipment approach >>> >>> 1 Heat the plastic and pour the rectangular shape oversize, Possibly >>> flattening down and spread it out as >>> you do. (How much it spreads naturally will be dependent on both >>> material and surface temperature. >>> If you have a big enough machine you want to use it to control the >>> pour path. >>> 2 cut off the edges and recycle the material with mill or saw. >>> 3. mill the top if the flattening does not leave the right height. >>> 4 possibly heat polish (slightly melt the surface) the form if glossy >>> surface it more important than sharp rectangular edges. >>> >>> You may want to reverse steps 2 and 3 and heat polish the top for a >>> glossy surface before cutting the edges. >>> >> Is it possible to pour PVC as you would do with molten metal? I mean >> because of the viscosity of the plastic at that temperature I always >> thought the only solution is to apply pressure wheter extruding it or >> injecting it. >> >> >> >> > ------------------------------------------------------------------------------ > 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 ------------------------------------------------------------------------------ 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
