Continuous Extrusion Degassing

Operational Logic

High-performance vacuum vents situated along the downstream section of the screw allow for the release of gaseous contaminants. Gases travel through these ports while the melt remains contained due to specific screw flight geometries that prevent leakage. The melt pool undergoes shear thinning and surface renewal as it passes the evacuation zone, which accelerates the diffusion of trapped species toward the vacuum interface.

Proper vacuum levels prevent the formation of bubbles that cause brittle failure in the final part.

Material Impact

Regrind material frequently carries high moisture content or volatile additives that trigger hydrolysis or surface defects during moulding. Continuous extrusion degassing serves as an essential remediation step when virgin resins mix with reclaimed feedstocks to maintain a consistent output. It corrects for variations in raw material hydration that would otherwise cause dimensional drift or inconsistent melt flow indexes.

Neglecting this step during the compounding of hygroscopic polymers results in a high scrap rate due to incomplete structural fusion.

Economic Consequence

Capital investment in dedicated pumping systems shifts the cost profile of a production line toward higher initial expenditure but lowers the price of finished goods through reduced defect rates. Operations that bypass this stage often face elevated reject volumes that exceed the amortized cost of the vacuum equipment. Efficiency gains derive from the ability to run higher percentages of lower-cost recyclate without compromising the physical properties required for technical applications.

Long-term reliability of the melt stream justifies the maintenance of the auxiliary hardware.