Introduction (1)Weaving Principle & Shuttle loom Dr. Jimmy Lam Institute of Textiles & Clothing
Learning Objectives • Weaving Principles • Different types of weaving machines • Production calculations • Discussion • To explain how woven fabrics are produced • Primary motions and auxiliary motions of weaving looms
Introduction • This is a process of interlacing two or more yarns at the right angles to each other to produce a woven fabric. • The yarn runs lengthwise is called warp (end). • The yarn runs crosswise is called weft (pick).
Weft (Pick) Warp (End) Basic Plain Weave Fabric
Weaving Principle (I)Basic Motion of Weaving Machine • There are Six motions on a loom (weaving machine). • The first three are called primary motions and the second three are called auxiliary motions. • Primary motions are: shedding, picking and beating up. • Auxiliary motions are : let-off, take-up and pattern.
Basic Weaving Mechanism Yarn Movement Hardness controls up/down movement of warp yarn Shuttle inserts weft yarn into the shed to form a cloth
Weaving Principle (II)Primary Motions • The function of primary motions is to separate warp yarn and form an opening so weft yarn can be passed inside the shed. • 1) Shedding: raising or lowering of the warp yarns by the hardness (wire) to make an opening for the weft yarn to pass through. • 2) Picking: the passage of the shuttle or other device across the loom to put a weft yarn in the shed. • 3) Beating-up: the pushing of each loose weft yarn into the cloth by the reed, after the shuttle has moved through the shed.
Weaving Principle (III)Auxiliary Motions • The functions of auxiliary motions are to continue supply the warp yarn to the weaving loom and take-up the cloth onto the cloth roll. • 4) Warp let-off: Unwinding of the warp beam to supply more warp yarn as the cloth is woven. • 5) Cloth take-up: the turning of the cloth roll to wind up the cloth as it is woven. • 6) Pattern: the vertical movement of the boxes in shuttle box loom
Weaving Loom Air-jet, shuttless loom Cloth
Hardness Warp Let-off Warp yarn is delivered to the loom Warp Yarn
Discussion • Discuss the functions of Primary motions and Auxiliary motions of weaving machine. • How can you increase the weaving machine production?
Weaving MachineShuttle Loom • Looms that use a shuttle to insert the weft yarn in the shed is called shuttle loom. • A shuttle is a wooden, boat-like device with a bobbin placed inside. • As a shuttle is thrown across the loom, the weft yarn unwinds from the bobbin, leaving a trail of yarn behind. • When the weft yarn inside the shuttle is almost exhausted, a full bobbin is automatically inserted into the shuttle, which allows weaving to continue without stop.
Shuttle for Weaving Loom Weft yarn is placed inside the shuttle. The whole shuttle is passed through the warp shed to form a fabric.
Shuttle LoomDisadvantages • Shuttle loom needs a pirn-winding (to re-supply the weft yarn in the shuttle). • The shuttle is big and heavy in weight. The loom is therefore slow in speed and noisy in operation because of the dynamic problems created by picking and checking mechanisms. • In addition, the shuttle sometimes causes abrasion on the warp yarn as it passes over them and may cause thread breaks.
The cloth rolls doffed off from the looms were delivered to cloth inspection room for inspection and quality grading.
Weaving machineShuttle loom • The use of shuttle loom is the slowest and least efficiency power weaving. • Explain why and how to improve them?