Fuselage Longerons Manufacturing Solutions
Common Customer Challenges
- Long, slender parts are prone to distortion during machining and heat treatment, making straightness and twist control difficult.
- Thin‑wall geometries and complex cross‑sections require optimized toolpaths and fixtures to avoid chatter and deflection.
- Titanium/high‑strength alloys cause rapid tool wear; productivity and tool life must be balanced.
- Hole position and mating surface tolerances for assembly interfaces are tight; stack‑up control is critical.
- 100% NDT coverage and complete material/process traceability are required for certification.
- Small batch, multi‑variant scheduling and quick changeovers are needed while keeping OEE high.
Solutions And Case Studies
Longerons (Aluminum/Titanium)
- Technical Points: Long slender machining, straightness/twist control, thin‑wall stability, weight‑reduction features.
- Process Route: Roughing → Stress relief → Precision machining → Assembly holes/countersink → Surface treatment → Straightening → NDT → Metrology.
- Success Case: Regional jet longerons (L=7.8 m), straightness ≤0.05 mm/1000 mm, wall 2.0–3.0 mm, cycle time −28%, delivery on‑time rate 99.6%.
Integrated Longerons With Brackets
- Technical Points: Co‑machining of mating faces and holes, tolerance stack‑up control, fixture datum strategy.
- Process Route: 5‑axis co‑machining → Precision reaming/tapping → Surface finish control → Trial fit.
- Success Case: Narrow‑body fuselage section, hole positional accuracy ±0.03 mm, first‑pass yield 98.7%, rework −42%.
Hybrid Assembly (Metal + Composite Interfaces)
- Technical Points: Dissimilar material joints, galvanic corrosion prevention, sealed interfaces, weight optimization.
- Process Route: Machining → Surface prep → Sealing/primer → Controlled assembly → Leak check.
- Success Case: Business jet sub‑assemblies, weight −12%, corrosion risk mitigated, assembly torque variation ≤5%.
Fuselage Longerons Manufacturing Process
Raw Materials And Incoming Materials Inspection
Process step description: Verify aluminum/titanium alloy grade, thickness, surface quality and heat treat condition; sample chemistry and mechanical properties. Equipment: Optical spectrometer, universal testing machine, CMM, ultrasonic thickness gauge, hardness tester, metallographic microscope.
Material Preparation And Cutting
Process step description: Cut sheet metal to required dimensions with minimal waste and proper edge quality for subsequent forming operations. Equipment: CNC cutting machine, laser cutter, waterjet cutter, shearing machine, edge deburring machine.
Rough Machining And Stock Removal
- Process step description: Remove excess material and establish basic geometry using high-efficiency roughing operations with proper fixturing.
- Equipment: CNC milling machine, turning center, machining center, roughing tools, precision fixtures.
Heat Treatment And Stress Relief
- Process step description: Apply solution treatment, aging or stress relief to achieve target mechanical properties and dimensional stability.
- Equipment: Heat treatment furnace, aging furnace, stress relief furnace, temperature monitoring system, atmosphere control.
Precision Machining And Finishing
- Process step description: Machine critical features, surfaces and assembly interfaces to specified dimensions and surface quality requirements.
- Equipment: 5-axis machining center, precision milling machine, turning center, grinding machine, CMM.
Assembly Hole Drilling And Tapping
- Process step description: Drill and tap assembly holes with high precision positioning and thread quality for structural connections.
- Equipment: CNC drilling machine, tapping machine, countersinking machine, thread gauge, hole position checker.
Precision Straightening (As Required)
- Process step description: Correct distortion on long structural members and verify straightness using precision straightening equipment.
- Equipment: Precision straightening machine, laser distance gauge, multi-point straightening fixture, straightness tester.
Surface Treatment And Coating
Process step description: Apply anodizing, primer coating or specialized surface treatments for corrosion resistance and paint adhesion. Equipment: Anodizing line, coating booth, curing oven, surface preparation system, thickness gauge.
Non-Destructive Testing (NDT)
Process step description: Perform 100% NDT inspection including ultrasonic, eddy current and penetrant testing for defect detection. Equipment: Ultrasonic testing system, eddy current tester, penetrant testing kit, X-ray inspection system, NDT certification equipment.
Dimensional Inspection And Metrology
Process step description: Verify dimensional accuracy, surface profile and geometric tolerances using advanced metrology equipment. Equipment: CMM, laser tracker, 3D scanner, surface profilometer, coordinate measuring arm.
Final Inspection And Documentation
Process step description: Conduct final quality checks, generate inspection reports and prepare documentation for airworthiness certification. Equipment: Visual inspection station, documentation system, barcode printer, quality management software.
Packaging And Shipping
Process step description: Apply protective packaging and shipping preparation to prevent damage during transportation and storage. Equipment: Protective packaging system, shipping fixtures, environmental monitoring, handling equipment.
Data Traceability And Quality Control
- Process step description: Maintain complete traceability of materials, processes and inspections for airworthiness compliance and quality control.
- Equipment: MES, data acquisition system, quality management system, barcode/RFID system, document management.
Wing Structural Parts Production Line
Production Line Layout And Configuration
- Overall Layout: Linear/U-shaped layout by process sequence to minimize handling and crane moves for long slender parts.
- Workstation Division: Material prep → Rough machining → Heat treatment/stress relief → Precision machining → Straightening → Hole making/countersink → Inspection/fit check → Packaging.
- Logistic Passage: Main aisle 5 m, auxiliary aisle 3 m; overhead cranes cover all long-part stations with direct hooks.
- Buffer Zone Setup: 4–8 hour WIP buffers between critical stations (heat treat, precision machining, straightening) to balance takt.
Equipment Configuration And Automation
- Rough machining station: 2–3 gantry machining centers (X ≥ 6 m), 1 heavy-duty milling center, anti-vibration fixtures; auto tool change and in-process probing.
- Heat treatment/stress relief: 1–2 furnaces (useful volume ≥ 6 m), aging/stress-relief furnace with closed-loop temperature control; automatic loading carts.
- Precision machining station: 2 five-axis centers (X ≥ 6–8 m), micro-boring/reaming heads, dedicated countersink units; on-machine measurement and compensation.
- Straightening station: Precision straightening press with multi-point actuators; laser line/distance gauges for closed-loop straightness/twist control.
- Drilling/reaming/countersink: Long-bed CNC drilling centers with programmable pitch and pattern; chip evacuation and surface integrity monitoring.
- Inspection/fit check: Large CMM (volume ≈ 4 m × 2 m × 1.5 m) or laser tracker cell; dedicated fit jigs for trial assembly of mating frames/skins.
- Automation: Robot/gantry loaders for long parts, automatic fixture ID and program call, tool life management, probe-based auto-compensation.
Production Flow And Material Handling
- Material Flow: Raw materials → Rough machining → Heat treatment → Precision machining → Assembly → Inspection → Packaging
- Handling: Overhead cranes (10–20 t) plus long-part lifters and soft slings; vacuum lifters for thin-wall extrusions; AGVs for station-to-station transfer.
- Storage: Long-part racking with protective saddles; FIFO lanes between heat treat and precision machining to stabilize throughput.
- ESD/protection: Protective edge guards and non-marring supports to prevent denting/scratches on thin walls.
