How is PVC made?
Polyvinyl Chloride is made from one of three emulsion processes:
Suspension polymerization
Emulsion polymerization
Bulk polymerization
Polyvinyl Chloride for Prototype Development on CNC Machines, 3D Printers, & Injection Molding Machines
Two main issues are working with PVC that makes it relatively problematic and not generally recommended for use by non-professionals. The first is the emission of toxic and corrosive gases when melting the material. This happens to some extent or another while 3D printing, CNC machining, and injection molding. We recommend taking a look at the MSDS data sheets for different chlorinated hydrocarbon gases like chlorobenzene and discussing the production process with a professional manufacturer. Second is the corrosive nature of PVC. This is problematic when PVC is repeatedly coming into contact with metal nozzles, cutters, or mold tools made from a material other than stainless steel or some other similarly corrosion-resistant metal.
3D Printing:
Polyvinyl Chloride is available in filament form as a plastic welding rod (the material used for welding), but it is not presently retrofit for specific use in 3D printing. Although there are a growing number of plastics and plastic substitutes available for 3D printing, by far, the two most common are still ABS and PLA. At Creative Mechanisms, we typically 3D print with ABS. For a list of reasons why and compare the two most common 3D printing plastics (ABS and PLA) for 3D printing, read here.
The biggest issue with PVC for 3D printing is its corrosive nature (potentially compromising typical machines' functionality if it were used over a longer period). An interesting kickstarter developed a PVC capable 3D printing nozzle (extruder head) put forward by engineer and entrepreneur Ron Steele that unfortunately closed without enough interest in 2014. You can take a look at the introductory pitch (video) here:
CNC Machining:
Polyvinyl Chloride can be cut on a CNC machine, but any machinist who has tried has probably experienced degradation in the cutter depending on the material it is made. PVC is corrosive and abrasive, and cutters that are not made from stainless steel or a comparably corrosive resistant material are likely to deteriorate over time.
Injection Molding:
Polyvinyl Chloride can be injected just like other plastics, but chlorine in the material complicates the process. This is because melted PVC can give off a corrosive, toxic gas. Accordingly, shops need to be equipped with good ventilation systems. Those that aren't are likely to be hesitant to work with the material. Additionally, unique corrosive resistant materials like stainless steel or chrome plating are required for the mold tool when injection molding PVC plastic. Shrinkage in PVC tends to be between one and two percent. It can still vary based on several factors, including material durometer (hardness), gate size, holding pressure, holding time, melt temperature, mold wall thickness, mold temperature, and the percentage and type of additives.
Is PVC Toxic?
PVC can pose a health hazard when burned as it emits hydrogen chloride (HCl) fumes. In applications where the likelihood of fire is high, PVC free electrical wire insulation is sometimes preferred. Fumes can also be emitted when melting the material (such as during prototyping and manufacturing processes like 3D printing, CNC machining, and injection molding). We recommend taking a look at the Material Safety Data Sheets (MSDS) for different chlorinated hydrocarbon gases like chlorobenzene and discussing the production process with a professional manufacturer.