EV Cable HFFR TPU Compounding Line in China

Illustration notice. Process illustrations are not verified photographs of this installation.

Project reference basis. Figures and configuration details are reported in the supplied project brief. They are reference values for the stated application, rather than verified acceptance results or a guarantee for another installation. Confirm the source records, material, tooling, operating schedule and test method when assessing a comparable project.

A leading national specialty cable material and high-tech polymer corporation in Jiangsu partnered with Haifeng to establish an automated high-filler compounding line for halogen-free flame-retardant (HFFR) thermoplastic polyurethane. The installation was commissioned to manufacture specialized jacket compounds for 1,000V high-power liquid-cooled electric vehicle (EV) charging cables.

Prior to this installation, the manufacturer operated legacy high-shear twin-screw lines. The excessive shear heating induced severe polymer chain scission, dropping compound elongation at break to 260% (well below the automotive benchmark of 400%) and causing brittle failure during cold-bend testing at -30°C. Furthermore, poor powder wetting generated agglomeration craters and rough surface pimples during continuous cable jacketing, causing frequent insulation breakdown during high-voltage spark testing.

Haifeng engineered an integrated low-shear compounding plant centered on the HF-TPU75-HFFR system. Featuring dual-stage forced side-feeding, gentle distributive mixing elements, and die-face water-ring pelletizing, the line incorporated 52 wt% mineral flame retardants at 600 kg/h, delivering UL94 V-0 (0.8 mm) flammability while preserving tensile elongation at 415%.

Review point: This is pellet/additive compounding rather than a primary liquid reactive-polymerization route. UL 94 V-0 at 0.8 mm and oxygen index concern the tested compound/specimen; they do not establish cable qualification or machine certification. Feeder accuracy and final dispersion are different measures.

Concept illustration: Generated concept illustration for process discussion; not a photograph of the specified machine, a customer facility or a delivered project.

Configuration reported in the supplied brief.

Haifeng engineered an automated compounding facility designed for bulky powder handling. Virgin polyether TPU base pellets are fed through Zone 1 gravimetric loss-in-weight feeders into an L/D = 52 co-rotating twin-screw extruder. The initial five barrel zones gently plasticize the polyurethane base into a steady melt pool under 175°C.

At Zones 6 and 8, two high-torque twin-screw side stuffers ram de-aerated aluminum trihydrate (ATH) and melamine cyanurate (MCA) powders directly into the molten polymer stream, achieving 52 wt% filler loading without hopper bridging or back-venting. Specially configured gear mixing blocks distribute the mineral particles into the matrix without thermal overheating, holding melt temperatures strictly below 190°C.

Dual vacuum degassing vents operating at 0.05 kPa extract moisture and trapped air from the mineral powder. The homogeneous compound is pumped into an enclosed water-ring die-face pelletizer, where carbide blades cut the strands into spherical pellets. The slurry is spin-dried centrifugally and classified, yielding smooth, blemish-free cable compounds capable of producing flawless cable jackets (Ra ≤ 1.2 µm).

This is pellet/additive compounding rather than a primary liquid reactive-polymerization route. UL 94 V-0 at 0.8 mm and oxygen index concern the tested compound/specimen; they do not establish cable qualification or machine certification. Feeder accuracy and final dispersion are different measures.