Jacquard Shedding

jacquard sheddingThe jacquard is a shedding device attached to the top of the hand loom or a power loom and controls a large number of warp threads with a view to produce the maximum variety of sheds (without and heald shaft) for ornamenting the fabrics.
Scope of Jacquard Shedding:
  1. It can be used for a large design which cannot be positive on tappet or dobby. (It can produce most complex or any design).
  2. It can produce any shape of design.
  3. One warp thread for each harness.
  4. Most costly fabric is produced. (Costing: Jacquard>Dobby>Tappet).
  5. No heald shaft is used.
  6. Every thread is controlled individually.
  7. It is possible to lift 2000-3000 yarns at any instant.
    1. A dobby shedding cannot be used suitably for producing beautiful and intricate (Complex) ornamental designs in forms and colors, in which a large number of warp threads are required to be controlled individually and in such case a jacquartd shedding is used.
    2. Jacquard shedding is however, an extensive form of weaving – as it is accompanied with designing, card cutting, lacing and all other jobs associated with.
    3. Speed- Jacquard<Dobby and Tappet.
Basic Principle of Jacquard Shedding:
Construction:
  1. In the figure the uprights are the hooks and horizontal lines are the needles.
  2. Needle board is perforated boards through the needles are pass.
  3. At the back of each needle a small fine brush spring or still wire is placed.
  4. Springs are held in position in the spring box.
  5. The wires of hooks are doubled at the base.
Principle:
  1. For jacquard shedding, punched card is used which is made according to design.
  2. Pattern chain is made which is placed on pattern cylinder.
  3. Card holes indicates warp up of the design.
  4. The knives from the griffe (Which are all fastened together) are moved up and down from the crank shaft of the loom.
  5. When the griffe begins to move upward, the cards of the perforated cylinder is pressed against the needles.
  6. It there is hole in the card, the needle directly opposite the hole will pass through it and in to the perforation the cylinder and the knife will take if the hook to which this needle is connected and forms the top line of shed.
  7. If the card is blank opposite any needle, it will pass back the hook and as the knife lifts, the hook is left down. Thus it is possible to lift nay of the jacquard for any pick and form the bottom line of the shed.
Differences between Jacquard shedding, Dobby shedding and Tappet shedding:
Jacquard shedding
Dobby shedding
Tappet shedding
1. Most complex mechanism.
1. Quite complex mechanism.
1. Simple mechanism.
2. Installation cost is high.
2. Installation cost is medium.
2. Installation cost is low.
3. 2-1000 yarns can be controlled collectively.
3. 2-36 yarns can be controlled collectively.
3. 2-8 yarns can be controlled collectively.
4. Jacquard is placed generally above the loom.
4. Dobby is placed generally above the loom.
4. Tappet is placed generally below the loom.
5. It can produce any shape of design.
5. It can produce square and rectangular design.
5. In can produce basic design.
6. Harness cord used.
6. Heald shaft used.
6. Heald shaft used.
7. Less production.
7. Less production.
7. Production is more than dobby shedding.

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