Custom Xaloy® Screw Design Improves Pipe Extrusion Melt Quality and Reduces Scrap by 100%
Achieving the highest quality melt in a pipe extrusion line is crucial because any deficiencies in the melt can significantly impact the final product. Several factors can affect the quality of the melt, such as screw design, resin sticking to the grooved feed section, and changes in melt temperature. It is critical to optimize the extrusion line to achieve the highest quality melt possible and ultimately produce a final product that meets all necessary specifications.
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THE CHALLENGE
An extrusion pipe manufacturer, located in Central America, was experiencing windows due to unmelts, rendering all product unusable. They were processing black high-density polyethylene (HDPE) with 20% regrind with a 130mm 33:1 barrier screw with a mixer in a Davis-Standard grooved feed extruder. Reaching out to Xaloy, the customer asked for a solution to eliminate their melt quality issues.
THE XALOY APPROACH
Xaloy application engineers performed a comprehensive analysis of the customer-provided process information. This enables our team to determine which screw design and materials of construction will work best with the customer’s application while correcting their processing issues.
THE XALOY SOLUTION
After evaluating the problem, our engineers recommended an Xaloy® Efficient™ barrier screw with a Nano™ and diamond mixer. The barrier section is designed to process the highly pressurized resin from the grooved feed section, while keeping shear rate and material temperature at reasonable levels. This screw, paired with a Nano and diamond mixer, increases overall product quality. This combination of mixers helps to provide superior dispersion throughout the polymer melt to help eliminate windows.
THE RESULT
With the addition of the Nano™ and diamond mixers to the barrier screw design, our customer reported immediate success. Melt quality increased, eliminating windows, and restoring line functionality. This line as outfitted ran 100% scrap for two months until it was idled. After installation of our screw design, the line was back up and running with a 0% scrap rate.
Process Improvements
- Windows (unmelts) eliminated
- Scrap rate went from 100% to 0%
