Warp Separation
The temporary division of the warp yarns into upper and lower sheets creates the path through which the weft yarn is inserted. The shed opening designates the height of this gap at the moment of weft insertion, measured from the bottom to the top yarn layers. This mechanical setting is carefully adjusted on the loom to match the dimensions of the weft carrier.
It determines the clearance available for the insertion of the weft yarn.
Insertion Clearance
A larger opening provides more space for the rapier or projectile to pass through without catching the warp yarns, reducing yarn breaks. However, increasing this distance puts greater tensile stress on the warp yarns, which can exceed the breaking strength of delicate linen yarns. Flax yarns have limited elongation, so the mill must balance the need for carrier clearance against the risk of warp yarn breakage due to excessive stretching.
Electronic controls allow the loom to optimize this height depending on the yarn characteristics.
Stress Limit
Finding the optimal height prevents excessive thread breakages and ensures clean weft passage. The setting is recorded in the loom setup sheets for each specific fabric quality. This practice maintains consistent fabric production efficiency.
