1. Air-covered yarn (abbreviated as empty bag, abbreviated as ACY) is a yarn that draws the outer fiber filament and spandex yarn through a certain type of nozzle at the same time, and forms a rhythmic network point through the regular spraying pressure of highly compressed air. Its fabric is soft and smooth to the touch;
2. Mechanically covered yarn (referred to as machine bag, abbreviated as SCY) is the outer fiber filament is constantly rotated and wound on the core yarn spandex that is drawn at a constant speed, which is twisted and has a twist (abbreviated as TPM in English), and the fabric style is flat and crisp is its main feature.
Empty and machine-wrapped yarns have their own advantages and disadvantages in downstream weaving mills. When the empty bag is warped on the air-jet loom, it generally needs to be sized, otherwise the fabric is easy to fluff and break the thread, etc., but the weft can be used directly. In terms of cost alone, the empty bag capacity is much higher than the bag capacity, which makes the price lower than the machine bag, which is convenient to reduce the cost of downstream weaving mills. Although the machine bag does not expose the core yarn, in addition to the uneven twist, it is not easy to produce quality problems during spinning and weaving, but the output is low, so the price is more than RMB5000/T higher than the empty bag of the same specification, and the price of fine denier covered yarn is even higher than the empty bag RMB10000/T of the same specification, so the cost of using the machine bag is greatly increased.