Custom Polyamide Tube Extrusion Line Manufacturers & Product Systems

Polyamides (specifically PA6, PA11, and PA12) are semi-crystalline engineering thermoplastics characterized by sharp crystalline melting points and exceptionally low melt viscosity above their liquidus temperatures. Standard polyolefin metering screws generate excessive localized shear heating, which degrades the amide linkage (-NH-CO-) and causes rapid melt flow fluctuation (surging). BAOD engineers proprietary barrier screws featuring shallow feed depths, decompression degasification chambers, and specialized Maddock mixers that enforce uniform thermal homogeneity while keeping shear stress strictly controlled.

Achieving structural adhesion between chemically dissimilar materials (such as non-polar barrier resins like EVOH or PVDF and polar polyamide layers) requires precise temperature equalization inside the co-extrusion die head. BAOD’s spiral co-extrusion crossheads utilize isolated thermal control zones for each individual polymer stream, preventing cross-channel heat transfer. Chemically engineered functionalized polyolefin or maleic anhydride tie-resins are distributed with balanced layer thickness ratios (typically 0.05mm - 0.10mm) to promote interfacial cross-linking without polymer degradation.

Nylon resins are highly hygroscopic. Moisture contents higher than 0.05% by weight cause hydrolytic chain scission during melt processing, resulting in severe embrittlement, foaming, and dimensional drift. Prior to extrusion on a BAOD line, PA pellets must be dried in a desiccant rotor dehumidifying dryer operating at a dew point of -40°C to -50°C, typically at 80°C to 90°C for 4 to 6 hours, and directly conveyed via sealed vacuum loading hoppers with inert nitrogen blanketing capabilities.

Our lines integrate a dual-stage closed loop: a continuous high-frequency dual-axis laser diameter gauge positioned directly at the vacuum sizing tank exit communicates via Profinet with the servo crawler haul-off and the vacuum level regulator. If an outer diameter drift as small as 0.005mm is detected, the line dynamically trims crawler traction velocity and vacuum pressure in milliseconds, maintaining a tight normal distribution capability (Cpk ≥ 1.67) at speeds up to 120 m/min.