Filament Winding Machine Product

Overview

Filament winding is a primary fabrication method for fiber-reinforced polymer (FRP) composite structures with rotational symmetry: pressure vessels, pipes, rocket motor cases, automotive driveshafts, and tennis rackets. Unlike hand layup (labor-intensive) or closed-mold injection (limited size), filament winding automates fiber placement, achieving high fiber volume fractions (55–70%) and precise orientation control.

The machine winds continuous roving fibers around a rotating Mandrel Spindle Assembly, pre-impregnating each strand in a Resin Bath & Immersion and laying it in helical or circumferential patterns. The Winding Carriage & Axes synchronizes axial fiber travel with mandrel rotation, controlling fiber angle (hoop, helical, axial). After winding completes, the part cures in an oven and is ejected by removing the mandrel.

Modern machines employ servo-driven motion axes, programmable logic controllers, and closed-loop fiber tension feedback, enabling complex multi-angle layups and short cycle times. A typical production run generates one 2.5 m diameter × 5 m long tank shell every 30–45 minutes.

Mandrel Spindle & Rotation

The Mandrel Shaft is a tapered steel spindle (hollow or solid, 25 mm to 2.0 m diameter, removable) on which composite plies accumulate. It rotates at 1–200 RPM controlled by the Hydraulic Power Unit:

• Small mandrels (tube or small tank): 100–200 RPM, synchronizing with slow fiber feed (10–20 m/min fiber speed).
• Large mandrels (rocket case, pressure vessel): 5–20 RPM, with faster fiber speed (30–50 m/min) keeping layup rate constant.

The relationship is: Fiber speed = Mandrel circumference × RPM × (carriage pitch distance), ensuring consistent fiber density. The Bearing Housing supports the shaft at two points (front and rear), with Ball Bearings handling radial loads from roving tension and thrust from winding forces. A dynamic Rotary Seal prevents resin leakage at the shaft exit.

Fiber Payout & Tension Control

The Fiber Payout & Tensioner assembly holds a Roving Creel with 8–24 spools of fiber roving (200–2400 tex bundles, E-glass or carbon), unwinding at controlled speed. Each tow passes through a Tension Block load cell and servo brake, maintaining 0.5–3.0 kg tension—critical for:

1. Even saturation: Loose fibers skip resin; tight fibers tear or bunch.
2. Precise layup: Consistent tension ensures predictable fiber angle and spacing.
3. Part quality: Wrinkles, voids, and dry spots reduce strength.

A Tow Separator hydraulic or mechanical actuator diverges multiple rovings at the Guide Eye (ceramic or polished steel tube), preventing fiber cross-over. Dancer Arm servo-controlled mechanical tensioners absorb fiber speed variations, feeding data back to the Control & PLC System PLC for real-time adjustment.

Resin Impregnation Bath

All fibers pass through a single Resin Bath & Immersion (typically epoxy, polyester, or vinyl-ester) at 40–70°C, pre-saturating the bundle before contact with the mandrel. The bath consists of:

• Resin Tank: Stainless-steel vessel (50–500 L) thermally insulated and heated to control resin viscosity (lower temperature = higher viscosity, higher speed = lower viscosity for consistent wetting).
• Resin Heater: Electric immersion or steam heat exchanger.
• Resin Circulation Pump: Gear pump (5–20 GPM) recirculating resin to maintain temperature and prevent settling of fillers/catalyst.
• Nip Roller: Rubber-coated precision rollers (typically two, one on each side) squeezing excess resin from the fiber bundle, controlling resin content (typically 30–45 wt% in final part, remainder is fiber).

The nip pressure is critical: too light and fibers remain dry; too heavy and all resin is squeezed out, creating voids. The ratio of roving tex to nip gap determines resin content—a formula well-studied in composites engineering:

Resin fraction (wt%) ≈ ρ_resin × nip_gap / (ρ_resin × nip_gap + ρ_fiber × fiber_tex)

A Resin Filter (10–25 micron mesh) on the return line removes cured particles and filler aggregates, extending bath life to 500–1000 parts per resin charge.

Carriage Motion & Fiber Placement

The Winding Carriage & Axes is a multi-axis stage traversing the fiber guide along the mandrel length (Z-axis, axial) and perpendicular distance (X-axis, radial), synchronizing both with mandrel rotation via the Control & PLC System PLC.

Winding angles:

• Hoop angle (0°): Fiber wraps circumferentially; mandrel rotates, carriage stationary. Dominates burst strength.
• Helical angle (±25° to ±80°): Carriage traverses axially while mandrel rotates. Fiber spirals around mandrel. At ±45°, loads are distributed between hoop and axial.
• Axial angle (90°): Carriage moves axially at high speed; mandrel rotation is minimal. Fiber runs lengthwise, limiting to low-load applications.

A typical layup sequences: [±45/90/0]_s (symmetric stacking, e.g., eight plies: +45, −45, 90, 0, 0, 90, −45, +45). The Z-Axis Servo Motor and X-Axis Servo Motor (AC or brushless, 0.2–2.0 kW each with gearboxes) drive Ball Screws via precision Axial Linear Axis and Radial Linear Axis slides. Rotary Encoders on each axis feed position back to the PLC, closing the loop: the PLC adjusts carriage velocity and mandrel RPM to maintain constant fiber layup rate.

Pitch calculation: For a helical wind at angle θ:

• Fiber advance per revolution = Mandrel circumference × tan(θ)
• Required carriage speed = Mandrel circumference × RPM × tan(θ) / 60 (mm/s)

Precision is critical: a 1 mm error in pitch spacing creates resin-rich or fiber-rich zones, weakening the part.

Control & Coordination

The Control & PLC System PLC runs winding algorithms that coordinate four variables:

1. Mandrel RPM (via Mandrel VFD variable frequency drive on a 3–15 kW AC motor).
2. Carriage Z-speed (via Z-Axis Servo Drive on Z servo motor).
3. Carriage X-position (via X-Axis Servo Drive on X servo motor).
4. Fiber tension (feedback from Tension Block load cells, adjusting servo brakes on roving spools).

Operators input via a Touchscreen HMI (7–10 inch industrial display) a winding pattern file (custom program per part), specifying:

• Mandrel diameter and length.
• Number of plies and fiber angles.
• Roving tex and fiber speed.
• Cure recipe (room temperature, oven ramp schedule).

The PLC executes the program, modulating Z-Axis Servo Drive, X-Axis Servo Drive, and Mandrel VFD in real-time. An Emergency Stop System circuit (dual-channel safety relay per EN 954-1 Category 3) de-energizes all motor drives if a guard is opened or E-stop button pressed.

Curing & Postcure

After winding completes, resin is partially cured (often just tack-free at room temperature, 2–4 hours) and the part may be ejected from the mandrel immediately or remain in place for oven postcure. The Curing Oven & Thermal (or in-place heating via Heating Element) applies a controlled ramp and soak schedule:

Example epoxy schedule:

• Ramp 1–2°C/min from room temperature to 80°C.
• Hold 80°C for 4 hours (volatile release).
• Ramp to 120°C.
• Hold 120°C for 2 hours (cross-link completion).
• Cool at 1°C/min (prevents thermal stress).

The Oven Controller executes this program, with temperature feedback from Temperature Sensors (PT100 RTD or K-type thermocouple) and circulation by a Circulation Fan for even heat distribution. Fully cured composites achieve target mechanical properties: carbon/epoxy at 600 MPa tensile, 50+ GPa modulus.

Hydraulic Power

The Hydraulic Power Unit supplies high-pressure (20–25 MPa typical) flow to the mandrel spindle motor and proportional valve manifold. A variable displacement Hydraulic Pump (30–100 cc/rev) driven by a 5–10 kW AC motor fills a Hydraulic Reservoir (100–300 L) with baffles and a heat exchanger (oil cools via fan or water). The Hydraulic Motor (fixed displacement, 30–100 cc/rev) drives the mandrel spindle via the Mandrel Drive Coupling.

A Valve Manifold integrates pressure-reducing, proportional directional, and load-check valves, modulating mandrel motor displacement and speed smoothly. Hydraulic Hose Assembliess (SAE EN286 4SP, JIC fittings) carry 21 MPa working pressure, 35 MPa proof test. A Return Filter (10 micron return) removes wear debris and oxidation products, maintaining fluid ISO 16/14/11 cleanliness.

Safety & Guarding

The Safety Guards & Enclosure enclosure surrounds the rotating mandrel and moving carriage, isolating high-energy zones. Interlocked Guard Panels (polycarbonate, 6–10 mm, hinged) close the opening; a Interlock Switch (coded magnetic sensor per EN 954-1) on each gate feeds the Emergency Stop System circuit. If any guard opens during wind, all motors de-energize within 100 ms. A Warning Light (LED beacon) flashes whenever the mandrel rotates, audible alarm also sounding. Hazard Labelss (ISO 7010 pictograms) warn of rotating shaft, pinch points, and hot resin.

Typical Production & Economics

A mid-size machine (1–2 m mandrel) producing composite pressure vessels for industrial or aerospace use:

• Cycle time: 30–60 minutes per part (wind only, plus 4–8 hour cure).
• Fiber weight fraction: 55–70% (balance is resin and voids).
• Part strength: Burst pressure 20–50 MPa (tensile), depending on fiber type and layup symmetry.
• Cost per part: Material (fiber + resin) typically $500–2000; labor (operator monitoring) $200–400 per shift; overhead amortized from equipment cost ($150k–500k).
• Waste: <5% scrap (trimmings, off-spec tension issues).

Modern aerospace and automotive suppliers operate filament winding machines in synchronized arrays (6–12 machines), winding pressure vessels, fan ducts, and driveshafts continuously, with upstream fiber braiding and downstream curing and NDT inspection in parallel.