Welcome to Basic Functions of the Weaving Loom where you will learn about “Shedding”, “Filling Insertion”, “Beat-up” and “Warp Control.”
“Shedding” is the process of creating an open path across and through the warp yarns by raising some warp threads by their harnesses and leaving others down. While the shed is open, the filling yarn is inserted. The shed is then changed as dictated by the pattern. The three methods of creating a shed are cam shedding, dobby shedding, and jacquard shedding.
“Filling insertion” refers to insertion of the weft yarn, or filling, into the warp shed. The oldest filling insertion method is with a shuttle. Newer methods include rapier, projectile, air-jet, and water-jet systems.
“Beat-up” is the loom motion that pushes (beats) the weft yarn into the “fell of the cloth.” After the pick has been inserted through the shed and while the harnesses are changing position, the reed moves forward with force to push the filling tightly into the fabric structure.
Warp control is the relationship on the loom between warp let-off (release of the warp yarn from the loom beam) and take-up of the formed fabric. The rate at which the loom beam turns and releases the warp yarn to the loom determines the production rate. The take-up rate controls the amount of warp yarn pulled forward after the pick insertion, which determines the number of picks per inch in the fabric. The let-off must be synchronized with the take-up to maintain the proper warp tension.