Ensuring uniform colour, ending pre-mixing and over-colouring

A patent-pending control system for feeding masterbatch to the injection moulding process ensures colour uniformity and saves costs by dosing colorant during the injection phase, when conventional feeders are inactive. Maguire introduced the technology at K 2019 as an option for the MGF gravimetric feeder. 

During the injection moulding cycle, about 75% of virgin resin enters the screw during the recovery phase and 25% during injection. Because conventional feeders add colour only during recovery, insufficient mixing can occur. This is particularly problematic when shot size approaches screw capacity or when the end product is translucent. In the new 100% Injection Colouring system, a special controller on the MGF feeder receives signals from the processing machine in both phases, ensuring that colour is added throughout the cycle.

100% injection colouring technology renders unnecessary two conventional solutions to inadequate mixing that pose added cost or complications: the use of an upstream pre-mixer, or over-colouring to compensate for insufficient mixing. Over-colouring adds raw material cost for opaque parts and is generally not possible with translucent parts.

“100% injection Colouring technology saves colour costs and ensures product uniformity, and it is particularly valuable when shot size is close to barrel capacity,” said Paul Edmondson, managing director of Maguire Europe. “With conventional feeders, there simply is not enough mixing time in the barrel to colour the 25% of barrel content to which colorant has not been added. Over-colouring 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.”