Nordson's plasticizing system for polycarbonate lens clarity

Nordson Corporation is set to  introduce at Fakuma 2015 (Hall A6, Stand A6-6404) its latest plasticizing system that combines special component designs and flow surfaces to help injection molders of optical-grade polycarbonate (PC), acrylic, and similar polymers to produce high-clarity, enhanced-quality parts.

The Nordson Xaloy PC Molding System responds to challenges encountered in molding optical-grade polymer by delivering a homogeneous melt with a minimum level of the shear that can cause yellowness or discoloration in PC; and by avoiding polymer sticking points or “dead” spots where blemishes such as black specks can form. Nordson recommends the system for processing lens-grade or colored PC for automotive lighting, eyeglasses, optical disks, and electrical and telecommunications components.   

The Nordson Xaloy PC Molding System provides superior quality in critical parts such as lenses by developing a fully homogeneous melt with optimal clarity, stressed Mark Colella, Nordson Xaloy global product manager.  

The components of the Nordson Xaloy PC Molding System include: Pulsar II Mixing Screw Modified for Polycarbonate which minimizes the color degradation of PC caused by shear during mixing and prevents the sticking of material at sites on the screw where specks can form; Barrel with X-800® Inlay composed of a nickel-based alloy with tungsten carbide to provide an especially hard surface with release properties that prevent polymer from sticking to the barrel; Valve for Free-Flowing Melt Delivery in which a valve with internal geometry designed for PC viscosity is included. Nordson recommends different valve types for screw diameters less than 80 mm, screw diameters greater than 80 mm, and flame retardant compounds, respectively, while valves with DyClad hard chrome plating are available to provide extra-hard, frictionless surfaces; and Nickel-plated end cap designed to smoothly transition the PC melt from the screw to the injection nozzle.