How to coil the end fiber in a meltblown fiber tray

Coiling meltblown fibers in a tray requires controlling fiber deposition, airflow, and cooling to form uniform loops without tangling.

Understanding Fiber Behavior

Meltblown fibers are extremely fine (1–30 microns) and are formed by extruding molten polymer through fine nozzles while high-velocity air stretches them into microfibers. As fibers exit the die, they are still partially molten and highly sensitive to airflow. The fibers initially move downward as straight segments, but as they travel further from the die, they bend and form loops due to airflow turbulence and velocity differences.

These loops are the basis for coiling in a tray.

Key Factors for Coiling

Airflow Control: The velocity and direction of the air significantly influence fiber motion. High-velocity air near the die (up to 130–160 m/s) causes fibers to stretch and oscillate, forming loops as they cool. Adjusting the airflow or using a suction fan under the tray can help guide fibers into controlled loops.

Tray Positioning: Place the fiber tray at an optimal distance from the die. Too close, and fibers are too straight; too far, and fibers may tangle excessively. Typical distances allow fibers to bend naturally into loops while still being soft enough to coil without breaking.

Cooling and Solidification: Fibers must cool sufficiently to retain their shape. Using a tray with slight airflow or a warm cooling profile ensures fibers remain pliable long enough to form loops but solidify before excessive entanglement occurs. Deposition Pattern: Move the tray or use a mechanical guide to distribute fibers evenly.

Controlled motion prevents dense clumping and allows fibers to coil in a uniform pattern. Some setups use a wire mesh or perforated tray to allow air to escape and fibers to settle gently. Polymer Properties: The type of polymer (e.g., polypropylene, polyethylene, polyester) affects fiber flexibility and cooling rate.

Softer polymers may require slower deposition or additional support to maintain looped coiling.

Practical Steps

Position the tray under the die at a distance where fibers begin to loop naturally. Adjust airflow and suction to guide fibers into the tray without excessive turbulence. Allow fibers to cool partially while forming loops, ensuring they do not stick together prematurely.

If necessary, gently move or shake the tray to encourage uniform coiling. Once fibers are solidified, they can be compacted or further processed for storage or web formation. By carefully managing airflow, tray distance, cooling, and polymer properties, you can achieve consistent coiling of meltblown fibers in a tray, minimizing tangling and preserving fiber quality for downstream applications.