I was recently contacted by a plant manager at a 
global leader and manufacturer of high-value injection-molded packaging and components. His plant serves consumer packaging, healthcare and industrial markets, and he was concerned their Polystyrene (PS) color change times were too long. The previous darker color would bleed out of a multi, valve-gated hot runner manifold and cause streaking in their lighter colored parts for about three hours. Both the blue and black colorants were the hardest colors to transition out of and successfully clean.
We examined, in depth, what the processing and purging conditions were to help them troubleshoot what was causing the colorant to bleed out for so long. We considered factors such as the processing temperatures of the manifold when running their production material, purge method, quantity of gates and cavities this tool had, gates sizes, and if there are certain gates that streaked more than others.
Mechanical grades love it when the turbulence and agitation are maximized!
Maximizing the pressures within the system will achieve optimal performance. By using safe maximum pressures, it will force mechanical grades into low pressure areas, which is usually where cleaning is needed the most.
To help this plant manager make faster color transitions and dramatically enhance his color change process, I had him implement these easy and quick, yet extremely effective, steps:
- Raise hot runner manifold temperatures from 420Fº to 450Fº.
- Purge multi, valve-gate hot runner manifold using “Open Mold Method.”
- Open and close valve pins to create as much pressure within the system as possible and perform air shots.
- Shut off the non-problematic valve gates and channel the purge compound into the problematic gates to administer as much pressure as possible.
The plant manager reported back they have been quite successful with a mechanical hot runner manifold purge compound. It cleaned the colorant out substantially faster and shaved off over two hours of machine downtime. They are now making good, sellable parts in a mere forty-five minutes, as a result of implementing these simple steps.
Ready to reduce your production downtime to protect your profits? Learn more about how purging compounds and process efficiency work in tandem.
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