Industrial technology provider Husky Injection Molding Systems is partnering with injection molding specialist Chem-Trend to design a color change system for packaging manufacturers to ensure repeatability and a more optimized and accurate process.
The collaboration devised a guided procedure accessible to operators through the Husky Altanium Mold Controller operator interface. The instructions outline a “simple yet highly effective” approach to setting up and performing the color change process explicitly for molds with hot runner systems.
Speaking to PackagingInsights, Michael Ellis, global business manager, hot runners and controllers at Husky Injection Molding, says color change systems are in high demand in the plastic sector at the moment.
“We especially see this in the consumer electronics and packaging markets, with strong increases in Asia. As part designs continue to become more and more complex, unique colors have essentially become a key component of plastic part design and crucial to the branding strategies for many of these consumer brands.”
“Molders are required to make many of the same parts in different colors now, to satisfy these consumer demands. Therefore reducing the impact this has on production and optimizing the color change is key for molders.”
Reducing change times
The joint approach is based on the process of using Chem-Trend’s Ultra Purge brand of purge compounds, which is designed to reduce color-change time and carbon formation in hot runner systems.
Matthew Cummings, product manager, Altanium at Husky Injection Molding, explains that color changes can be time-consuming based on pigment selection and process setup.
“The design of the hot runner can also impact color change times depending on the melt channel layout and sizes, temperature uniformity, and the number of hang-up spots such as manifold plugs and large gate bubbles. Other factors include a lack of proper planning, using a non-proven color change process, or operator error.”
Trial results showed up to an 85 percent reduction in scrap and an 80 percent increase in mold cleaning efficiency when following the duo’s new process.
Fighting carbon buildup
Cummings says the color change process is not necessarily a contributor to carbon buildup in the hot runner.
“Generally, carbon deposits result from thermally sensitive resin degrading after long residence times at high temperatures. A typical color change process without purge compound will not effectively remove these carbon deposits resulting in black specs in modeled parts over many cycles.”
“First, you need to verify the Hot Runner system is both designed for color change and suitable and optimized for the specific application.”
This means selecting the correct gating method and designing the system based on optimal temperature and pressure profiles, he says.
“The recommended color change procedure should then be followed to minimize the processing time, and if a purging compound is used, it must be food grade.”
The collaboration says their new design could significantly reduce cost and time for industry players who “have a lot at stake” during color change processes.
By Louis Gore-Langton, with additional reporting by Anni Schleicher
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