The air change process is mainly completed through a dedicated air change nozzle. The specific steps are as follows:

1.Filament Feeding: Multiple polypropylene filaments (raw yarns) enter the nozzle in parallel.

2.Air-Jet Deformation: High-pressure air is injected laterally into the nozzle, impacting the filaments. This causes them to become turbulent, entangle, and undergo localized twisting within the airflow.

3.Setting & Cooling: The deformed filament bundle passes through a cooling zone to solidify its structure, resulting in an air-textured yarn with a fluffy appearance, surface hairiness, or "slub"-like irregularities.

By adjusting parameters such as air pressure, filament speed, and nozzle design, products with varying degrees of bulkiness, thickness variation, or hairiness can be produced.