1 Standard Multi-Layer Automotive Fuel Hose Material Structure (Production Benchmark)

Option 1: 3-Layer Cost-Effective Fuel Hose (For Light Commercial Vehicles)

1. Inner layer: PA12 / PA6 (0.18–0.25mm, fuel & alcohol resistance)
2. Middle barrier layer: EVOH (0.08–0.12mm, hydrocarbon permeation block)
3. Outer protective layer: Modified PA12 / flexible TPU (0.3–0.5mm, anti-abrasion & anti-UV)

Option 2: 5-Layer High-Grade Fuel Hose (Passenger Car Euro 7 Compliance)

1. Inner PA12 fuel contact layer
2. Inner adhesive tie resin layer (bond PA and EVOH)
3. EVOH ultra-low permeation barrier core
4. Outer adhesive tie resin layer
5. Outer impact-resistant PA12 shell
   Key production threshold: Each single layer thickness tolerance ≤±2% of nominal value; total tube OD tolerance ±0.05mm, no interlayer separation after cold/hot cycling testing.

2 Full Co-Extrusion Line Configuration Recommended by Qingdao JBD

2.1 Matched Independent Precision Single-Screw Extruder Group (Core Unit)

1) Main Extruder (SJ45 for Inner/Outer PA Layers)

• Screw specification: 30:1 L/D segmented low-shear 38CrMoAlA fully nitrided screw, 316L food/automotive-grade stainless melt flow path
• Heating system: 6 independent PID heating zones, ±1°C temperature accuracy, forced air rapid cooling to cap PA melt temperature at 230–260°C
• Drive: Permanent magnet VFD motor (11kW), low torque fluctuation to stabilize PA melt output
• Gearbox: Oversized heavy-duty thrust bearing, 18-month factory warranty standard

2) Auxiliary EVOH Barrier Extruder (SJ30 Mini Co-Extruder)

3) Tie Resin Auxiliary Extruder (SJ25, Only for 5-Layer Lines)

2.2 Multi-Layer Spiral Mandrel Co-Extrusion Die Head (Production Heart)

1. Independent isolated flow channels for each melt stream, separate heating loops to maintain individual material processing temperatures before convergence
2. Spiral homogenization runners to balance circumferential layer thickness, barrier layer deviation controlled within ±2%
3. Quick-disconnect flange design for fast material grade switching and daily die cleaning to remove EV/EVOH carbon deposits
4. Full S136 mold steel mirror polishing, no dead flow zones that generate black impurity specks in finished fuel hoses
   Standard deliverable: Full die layer thickness calibration report after 72h FAT full-load testing at JBD factory.

2.3 Tiered Vacuum Constant-Temperature Sizing & Cooling System

1. Short primary vacuum calibration chamber (1.8m): -0.06~-0.08MPa stable negative pressure copper sizing sleeve locks roundness instantly right after co-extrusion
2. Segmented gradient spray cooling bath (7m total length): 3 independent cooling zones with chiller-controlled 12–16°C circulating water, gradual solidification eliminates internal residual stress between composite layers
3. High-pressure air knife drying station: Removes surface water before traction to avoid haul-off speed slippage and layer thickness drift
   All tank inner walls, sizing sleeves adopt SUS304 stainless steel, compliant with automotive component clean manufacturing standards.

2.4 High-Servo Synchronized Haul-Off & Fixed-Length Cutting Unit

1. Double caterpillar belt traction with dual servo closed-loop linkage, speed stability error ≤0.3% across 30–120 m/min line speed range; wide soft rubber belts prevent tube surface indentation
2. Low-inertia rotary servo cutter with hard alloy blades, clean burr-free cuts for fuel hose end connections; cutting length tolerance ±0.2mm
3. Anti-static sorting conveyor to avoid thin multi-layer tube static adhesion post-cutting

2.5 Siemens SMART LINE Full Closed-Loop Intelligent Control System

2.6 Matching Special Auxiliary Equipment for Multi-Layer Fuel Tube Production

1. Separate low-temperature dehumidifying dryers for PA12 and EVOH: EVOH absorbs moisture rapidly; moisture above 300ppm creates microbubbles inside barrier layers, failing permeation testing
2. Sealed vacuum auto feeding system: Dust-free raw material delivery to avoid metal/foreign particle contamination (critical for automotive part quality)
3. Online laser outer diameter + ultrasonic multi-layer thickness detector: Real-time automatic layer deviation alarm during continuous running
4. Quick-clean structural design for all extruders & die: Fast-release clamps cut color/material change downtime by 60% vs generic lines

3 Core Performance Benchmark of JBD Multi-Layer Fuel Hose Co-Extrusion Line

4 Why Generic Multi-Extruder Combinations Fail Automotive Fuel Hose Production

1. Independent non-synchronized extruders cause EVOH barrier layer offset or partial thinning, leading to failed fuel permeation testing
2. Single shared heating die head without isolated melt channels raises EVOH temperature over 240°C, generating gel particles inside the tube wall
3. Simple single-stage water cooling without vacuum sizing produces oval hoses unfit for automotive assembly joints
4. Ordinary inverter traction with large speed fluctuation creates inconsistent barrier thickness along tube length
5. Lack of dedicated EVOH low-shear screws triggers material carbonization and high scrap rates

5 JBD Full-Line FAT Factory Acceptance Testing Standards for Fuel Hose Co-Extruders