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Hot Runners Tri-layer hot runner systems complement co-injection

Editor: Eric Culp

Mold-Masters says its Iris co-injection system is well-suited to the beverage, caps and closures, food container and medical industries, and the company’s proprietary hot runners play a central role in the technology.

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The replaceable nozzle tip splits the skin flow into two separate streams and then brings the barrier flow front in between them.
The replaceable nozzle tip splits the skin flow into two separate streams and then brings the barrier flow front in between them.
(Source: Mold-Masters)

Iris is a compact co-injection nozzle manifold technology that combines melt streams and provides balanced fill-valve gate control of the opening and closing movements of the servo-actuated valve gate pins to achieve fast cycle times and precise cavity fill, according to Mold-Masters. The co-injection results are obtained by a precise, integrated control of dosing, flow and the pressure of the two melt streams.

Process, range of applications continue to evolve

The Iris co-injection technology is currently available for 32- or 48-cavity tools and further application possibilities are continually evolving. According to Mold-Masters, the Iris technology is ideal for use in beverage caps and closures, food containers, and medical applications. Wherever barrier layers are required to prevent permeation of oxygen and migration of CO2 or stop the entry of moisture for medicine or food containers, the Iris system is said to provide a comprehensive solution for process optimisation and cost reduction.

Balanced filling critical for successful co-injection

The company explained that this co-injection technology can create a 3% barrier layer encased in a skin through the controlled interaction of core technologies within the hot runner.

The molten plastic for both the skin and core layers is conveyed to the patent-pending hot runner nozzles using Mold-Masters iFlow manifold technology, the company said. By using multi-piece manifolds, brazed together using a proprietary process, the melt is conveyed in the same rheological condition and in equal measure to each nozzle, it explained. The valve gates are controlled throughout their entire stroke using a servo-driven synchro-plate system, called E-Drive. The E-Drive ensures that each gate opens at the same time and that the valve pin in each nozzle is in exactly the same position during the critical injection sequence.

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