Everything You Need To Know About PVC Plastic-4
What Are The Different Types of PVC?
Polyvinyl Chloride is widely available in two broad categories: rigid and flexible. Each type comes with its own set of advantages and ideal uses for different industries. Flexible PVC can act as electrical cable insulation and a rubber alternative. Rigid PVC has various uses in construction and plumbing, providing a lightweight, cost-effective, and durable material to use.
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.
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.
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.
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.
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.