WATER-JET LOOMS:-

History, Working Principle, Advantages and disadvantages:-

Jet weaving looms are divided into two categories, (1) air-jet loom and (2) water-jet loom according to the medium of weft insertion. The weft thread is transported through the shed with the help of air or water-jet. Secondary jets located in the shed assist the main jet in transporting the thread . This technology can only be used for light weight fabrics. Jet looms have the highest weft insertion speed of all looms but they are limited with regard to suitable weft material. Water-jet loom can produce superior high quality fabrics that have good appearance and feel.

image of water jet loom ref:- www.tsudkoma.co.jp

A water-jet loom is similar to an air-jet loom but uses water instead of air to transport the weft yarn around the shed . A water-jet loom inserts the filling yarn by highly pressurized water. The tractive force is provided by the relative velocity between the filling yarn and the water-jet. If there is no velocity difference between the water and yarn , there would be no tension on the yarn which would result in curling and snarling of the yarn. The tractive force can be affected by the viscosity of the water and the roughness and length of the filling yarn, higher viscosity cause higher tractive force . The viscosity of water depends upon the temperature.

Water-jet weaving machines are produced only by few manufacturer of light and medium weight fabrics with standard characteristics and in water repellent fiber material, primarily multi filament synthetic yarn . Water-jet machines are extensively used in East Asia, but have limited importance in the other countries. They are characterised in particular by high insertion performance and low energy consumption.

Water-jet loom is not used as frequently as air-jet, but they are preferred for some types of fabrics . The process is unsuitable for yarn of hdrophillic fibers because the fabrics pick-up too much moisture . Water soluble warp , sizings are used on most staple warp yarns. Therefore the use of water-jet loom is restricted to filament yarns of acetate, nylon , polyester and glass yarns that are non absorbent and those that do not lose strength when wet. Futher more, these fabrics come off the loom wet and must be dried. In this technique a water-jet is short under force and when it , a weft yarn. The force of the water and it is propelled across the shed carries the yarn to the opposite side . This machine is economical in its operation. A water-jet of only 0.1 centimeter (cms) is sufficient to carry a yarn across a 48 inches shed. The amount of water required for each weft yarn is less then 2.0 cubic centimetre. Water-jet loom can reach speed of 2,000 meter of pick per minute.

Both air and water jet weaving machines weaves rapidly, provide for laying different colours in weft direction and produce uniform, high quality fabrics. They are less noisy and require less space than most other types loom . They cause minimum damage to warp yarn during weaving operation, because the air or water jets are less abrasive than many metal parts.

The speed of shuttle less weaving mechanism can be compared by measuring the picks per minute (ppm) or yards laid per minute (ypm) in weft insertion. In 1990 , the top speed for projectile weaving machine was 420 ppm with between 1000 and 1202, yards per minute weft insertion. Flexible rapier weaving machine offered at 524 ppm and rigid rapier 475 ppm, laying weft upto 1404 and 930 ypm, respectively. Air-jet could lay as many as 1200 ppm and water-jet upto 1500 ppm laying 2145 and 2360 ypm respectively.

If a fabric 60" wide is woven on each machine at density of 50 picks per inch approximately, 84 yards of weft yarn would be needed to produce an inch of fabrics. In theory of the projectile loom would produce approximately 8.4 inches of fabric per minute, the flexible rapier , 10.5 inches, the rigid rapier, 9.5 inches , the air jet , 24 inches and water-jet 30 inches . The slowest of the machines could produce a yard of fabric 4.3 minutes and the fastest would take just 1.3 minutes Seldom do weavning machine operate at full capacity , but even at 50 % effeciency such machines could produce a yard of every 2.5 minute.

Ref:-https://textileleaner.net