Preparing the Warp Yarns for Weaving in loom

-->

Preliminary Steps for warp yarn preparation:

Before their use on the weaving loom, warp and filling yarns must be prepared for weaving. The essential characteristics of suitable warp and filling yarns differ. Warp yarns undergo greater stress and abrasion during weaving than do filling yarns; therefore, warp yarns must be strong enough to withstand these pressures. Warp yarns must be clean, free from knots, and uniform in size. A single warp yarn is called an end warp yarns are wound onto the warp beam from many cylindrical packages of yarns, which are called cheeses. To strengthen and lubricate warp yarns, sizing or slashing is added. Size is made up of starches or synthetic polymers such as polyvinyl alcohol (PVA) that act as lubricants. The yarns are passed from one warp beam through a solution of sizing material. The sized yarns are dried immediately after treatment and are wound into another warp beam. Sizing is not always required on filament yarn warps.

The warp beam containing the sized yarns is placed on the loom. In preparation for weaving, each warp end (yarn) must be threaded through its own drop wire, heddle eye, and reed dent. The drop wire is a device that will stop the loom if an end should break, the heddle eye is the opening in a heddle that carries the yarn, and the reed dent is an opening in the reed, the comb like device that will push each filling yarn close against the completed fabric.Placing the warp yarns on the loom is done either by drawing-in or by tying-in. If warp yarns from a previously woven fabric are in place and if that fabric had the same number of warps, the new warps are tied into place by attaching them to the warps already on the loom.If the new warp is different from that previously woven or if there is no warp on the loom, then the warps must be drawn-in. To draw-in or tie-in each end by hand would be enormously time consuming; therefore, a variety of machines has been developed for drawing-in. A separate machine can be used fot each step (that is, drawing through the drop wire, the heddle eye, and the reed dent), or one machine can perform all three steps. When a loom makes the same fabric, warp after warp, the new warp can be tied-in to the old.

Heddle wires are held in frames called harnesses. The number of harnesses required for the loom is determined by the weave. 

The warp beam: - warp beam, located in the back of the loom, is a large roller on which all of the warp yarns to be used for the cloth are wound parallel to each other If the fabric is to have warp stripes, the various yarns are wound onto the beam in color groupings to obtain the desired colored stripe effect.

Heddles: - Each with a hole (eye) in the middle. Each warp yarn is threaded through the eye of one heddle. Thus being controlled by that harness.

Harnesses: - The warp yarns pass through the harnesses, which look like picture frames holding many thin vertical wires called heddles, each with a hole (eye) in the middle. Each warp yarn is threaded through the eye of one heddle. Thus being controlled by that harness. The purpose of the harnesses is to raise and lower the warp yarns. The number of harnesses varies from twc to about thirty, depending upon the complexity of the weave.

Shuttle:- A shuttle is used, which is a boat-like device to carry the filling yarn on a stick called a quill or bobbin, As the shuttle moves from one side of the loom to the other, it leaves a trail of filling yarn behind it. The shuttle passes over the lower set of warp yarns and under the upper set. The shuttle stays in a box located at the end of the shed. When a bobbin becomes empty, a full one automatically replaces it.

Reed:- The reed is a frame with thin, vertical non-movable wires. Narrow openings or dents exist between the wires, the purpose of which is to keep the warp yarns separated. The reed resembles a comb and pushes the loose pick in the shed up to the edge of the already made cloth and returns to a position near the harnesses. The shuttle passes in front of the reed.

Cloth roll:- The cloth is slowly wound onto the cloth roll, located in the front of the loom.

-->