A patent-pending color metering control system for injection molding ensures color uniformity and saves costs by dosing colorant during the injection phase, when conventional color and additive metering systems are inactive. The technology will be introduced to liquid color users at NPE2018 by Riverdale Global and is expected to be adapted for solids-metering systems from affiliate Maguire Products, Inc.
 |
During the injection molding cycle, about 75% of virgin resin enters the screw during the screw recovery phase and 25% during injection. Because conventional metering systems add color only during recovery, insufficient mixing can occur, which is particularly problematic when shot size approaches screw capacity or when the end product is translucent.
In the new 100% Injection Coloring™ system, a special controller receives signals from the processing machine for both phases, ensuring that color is added throughout the cycle. Metering takes place at a faster rate during injection because of the rapid screw movement during that phase.
100% Injection Coloring technology renders unnecessary two conventional solutions to inadequate mixing that pose added cost or complications: the use of an upstream pre-mixer, or over-coloring to compensate for insufficient mixing. Over-coloring adds raw material cost for opaque parts and is generally not possible with translucent parts.
A controller outfitted with 100% Injection Coloring technology is available to liquid color users at no cost from Riverdale Global, which supplies metering equipment as part of its service to customers. The technology is also expected to be applicable in solids metering systems, including Maguire’s MGF™ gravimetric feeder, but will require a new controller that is currently in development.
“100% Injection Coloring technology saves color costs and ensures product uniformity in many molding applications and is particularly valuable when shot size is close to barrel capacity,” said Paul Maguire, president of Riverdale Global. “With conventional color metering systems, there simply is not enough mixing time in the barrel to color the 25% of barrel content to which colorant has not been added. Over-coloring can usually fix the problem, but not always, and especially not with translucent parts. For these you need to use either a larger machine or an upstream pre-mixer.”
About Riverdale Global
Riverdale Global specializes in liquid color management for the plastics industry through our sealed color delivery system, computerized color technology, and global service network. The company’s world headquarters is in Aston, Pennsylvania, U.S.A., with international offices based in the United Kingdom, Dubai, Singapore, and China. The Riverdale legacy dates back to the early 1900s as a supplier of dyes and industrial chemicals with a focus today on economy through process automation, sustainability and local service.
