PVC Injection Molding Technology
Negri Bossi are one of the market leaders in supplying injection molding machinery for processing PVC.
Even modern grades of Rigid PVC are less heat stable and have a smaller ‘processing window’ than most other thermoplastics. Flexible PVC can usually be processed on a standard injection molding machine, often with a standard screw configuration, whilst most grades of Rigid PVC require a special machine application to ensure optimal processing conditions.
Negri Bossi’s PVC molding technology has been developed to provide consistent and cost-effective production of visually and dimensionally perfect parts. Rather than offering a slightly modified standard machine, Negri Bossi have developed a more bespoke solution that provides the low shear, high torque, greater temperature regulation and resistance to chemical attack needed.
To demonstrate the degree of thought that goes into their PVC molding machines, anti-corrosive components such as chrome plated tie-bars are also specified, making sure that mechanical integrity and cosmetic appearance are preserved in the longer term.
Negri Bossi’s high level of modularity allows perfect matching of injection unit to clamp size. This is most important for PVC, where residence times are particularly critical, but items such as drainage products require large tools with multiple moving cores.
Our ST servo-hydraulic technology is particularly suited to the typical “duty cycle” associated with PVC components with the long static phases involved. This provides high performance whilst maintaining low energy consumption. These benefits are also available on the larger Vector models when specifying the smart energy solution.
Negri Bossi has developed specific injection unit solutions for rigid PVC, with low compression ratio screw profiles, the option of monolithic screw design to reduce ‘hang-ups’ and barrel cooling fans/mica bands to aid the removal of excess shear heat. On screw sizes of 80mm and over, internal screw cooling is also an option.
PVC molding machine models offer high torque hydraulic screw drive or optional electric screw drive on the ST range. Vector machines already have electric screw drive and can also be fitted with reduction gearboxes. These specifications provide the torque and screw speed stability required for optimum material processing.