Heddles are also called weaving healds, which can be divided into wire healds/heddles and flat healds/heddles. The wire healds used in shuttle looms are mostly nylon wire healds and steel wire healds. Flat healds are used for shuttleless looms, and the heald is the way the warp yarns enter the weaving process.

The role of steel heald in weaving is the arrangement of warp threads and the formation of shedding. The warp thread arrangement is based on the fabric structure, the warp threads are passed through the eyelets manually or automatically and through the machine, and they are arranged in an orderly manner. The shedding is formed because after the warp yarn passes through the heddle eye, the lifting mechanism moves up and down repeatedly, driving the warp yarn to form a shed.

Compared with the wire healds used in traditional shuttle looms, flat healds have these characteristics:
1. Simple structure, easy to manufacture, suitable for automatic production.
2. High strength, good elasticity and long service life.
3. Since there is no twist in the heddle loop and the eyelet, the warp yarn can be shed more greatly, thereby improving the quality of the fabric.
4. The flat steel heald layered structure improves the density of warp yarns and is suitable for high-density light fabrics.
5. The heald eye is located 10mm below the center position, and the balance center is lower, which is convenient for the automatic drawing-in machine.