PVC Molding

Are you molding flexible or semi rigid ? Semi rigid is more forgiving in my experience. Low compression screw with freeflow checkring is a must . No idle residence time of screw over five minutes.......period. Lowernozzle heats and purge with low temp melting PE if long interruption expected yeah you will get some cloudy parts at restarts but it's better than the black specks,fumes and teardown to clean head and screw.

If molding flexible, remember it's possible to mold a part bigger than the steel so processes documentation must be accurate to be duplicated or you'll always be chasing dimensions.

sk

PS: see archived posts on this

PVC outgasses chlorine & hydrochloric acid. Molds etc. will live longer if stainless or plated.

PVC is shear sensitive. There are specific screw designs for PVC, but if using a general purpose screw, use one with low compression and a long transition zone. Don't race the RPM.

And of course don't mix PVC & acetal.

Thanks Bill ,for the comments

DO: - have an exhaust hood over the machine

DON'T PANIC - the only 'nasty' thing about PVC is when you burn it, the fumes are acidic. DON'T BURN IT!

There is no panic here, it's just another plastic. No you don't have to make everything out of stainless steel, Yes, you should be 'gentle' with it - PVC is not very tolerant to over/under heating.

There are people who run nothing but PVC and have no trouble doing it and don't need anything fancy to be successful.

The only thing I'd recommend, that I'd recommend about any plastic - if you don't know what you're doing in terms of molding it, you'll get a lot of scrap. Read the instructions, make sure your process and equipment are robust. Venting is good, minimal clamp is good. But then again this applies universally.

Bill Tobin