Essential Weaving Operations in loom

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Essential Weaving Operations

On the conventional loom or weaving machine, the warp beam is mounted at the back and the warp yarns are conveyed to a cylinder called the cloth roll, which is at the front of the loom and on which the fabric is rolled as it is constructed. Supported on the weaving machine frame between these two cylinders (the warp beam and the cloth beam), the warp yarns are ready to be interlaced by the filling yarns that run in the width of the cloth, thus producing the woven fabric. 

Textile yarn that is to be used for the filling must be packaged in some form that allows it to be unwound easily for transport through the shed. In shuttle looms the device that carries the yarn across the shed is called a shuttle and is made up of a wooden carrier into which a quill, or prim, is placed. The filling yarn is wound onto the quills from larger packages of yarn. For shuttle-less looms this step of winding quills is unnecessary because filling yarn is drawn directly from large packages carIn any type of weaving, four operations are fundamental. They are performed in sequence and are constantly repeated: 

• Shedding –raising specific warp yarns by means of the harness or heddle frame. The shed is formed by raising the harnesses to form an open area between the sets of warps. The formation of the shed is known as shedding. 

• Picking –inserting filling yarns through the shed. While the shed is open, the yarn is transported across the opening, laying a filling yarn across the width of the loom. The insertion of the filling is known as picking. A single filling yarn is known as a pick. Speed of weaving machines is generally expressed as the number of picks per minute, yards or meters of filling inserted per minute, or yards or meters of fabric per hour. Speed obviously is related to the width of the loom. Wider looms, weaving wider fabrics, would require more time for one filling insertion. 

• Beating Up (Battening)–pushing filling yarns firmly in place by means of the reed 

• aking up and letting off–winding the finished fabric on the cloth beam and releasing more of the warp from the warp beam. 

• Monitoring Yarn Breakage - There is always the danger that a warp or filling yarn may break during weaving, causing a flaw in the cloth. Warp yarns are threaded through drop wires, small metal plates with holes, which are drawn down when a yarn breaks or they may be monitored by electronic scanners that indicate when a yarn is broken. Through signals resulting from either the drop wires or a break in the electronic contact, the loom is shut off, allowing the broken yarn to be repaired 

YARN TRANSPORT METHODS 

The carrier used for transporting the filling yarn may differ from one kind of loom to another. The different devices used form the basis for classifying different types of looms. Within the industry many people refer to newer equipment as weaving machines rather than looms. Weaving machines vary from older, shuttle looms to modern shuttle-less machines with sophisticated electronic controls.

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