Re: [CAD_CAM_EDM_DRO] routing PVC & fumes

One of the things I do for a living is design dies for extruding and
injection plastic. One of the most extruded is PVC. Now the stuff is
considered to be a self extinguishing plastic, meaning is doesn't support
combustion. It goes out. This is particularily true of the so-called rigid
forms. The flexible forms have so much plastisizer in them them that it will
show up as fog on the inside of the windows in cars as in migrates out of
the dashboard cover. The platisizer may burn in those cases but machining
such soft forms would be nearly impossible. If you run it fast enough to
cause it to smoke it would melt back together but it could give off chlorine
gas. Heat will cause it to decompose and the "C" in the name is chloride.
One of the problems in molding it is if it is heated too much it gives off
the chlorine which combines with water vapor in the air and the resulting
hydrochloric acid eats up the dies. It is easily routed and no problem
should expected if you treat it as wood. Although you may need to play with
the speed to feed ratio to keep the chips from remelt to the cut surface.
Scott