A large shed opening height generates high tension on warp yarns at the heddle area, which easily causes warp breakage.
Increasing the shed opening height reduces adhesion of warp hairiness, keeps warp yarns stretched taut, forms a distinct shed, and lowers weft stop failures.
A larger shed opening improves beating-up performance, facilitating beating-up action and fabric formation.
If the shed opening height is too small, the weft yarn will be obstructed when entering and exiting the fabric fell, easily resulting in weft stops and fabric defects such as weft shrinkage, weft slipping-off and double weft.

Key Points for Setting Shed Opening Height
The shed opening height should be kept as small as possible while meeting the requirements of weft insertion process.
When more heald frames are used, the tension difference between warp yarns on front and rear healds becomes greater. A semi-clear shed is recommended to reduce the incremental difference in opening height between adjacent heald frames.
A relatively small shed opening height shall be adopted for lightweight sheer fabrics, while a larger one for heavy dense fabrics.
Appropriately reduce warp tension when a large shed opening height is applied; moderately increase warp tension when a small shed opening height is set.