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On the diagram to the right, the cards are fastened into a continuous chain 1 which passes over a square box. At each quarter rotation a new card is presented to the Jacquard head which represents one row. The box swings from the right to the position shown and presses against the control rods 2. Where there is a hole the rod passes through the card and is unmoved whereas if the hole is not punched the rod is pushed to the left.
Each rod acts upon a hook 3. When the rod is pushed in the hook moves out of position to the left, a rod that is not pushed in leaves its hook in place. A beam 4 then rises under the hooks and those hooks in the rest location are raised; the hooks that have been displaced are not moved by the beam. Each hook can have multiple cords 5.
The cords pass through a guide 6 and are attached to their heddle 7 and a return weight 8. The heddles raise the warp to create the shed through which the shuttle carrying the weft will pass. A loom with a hook head might have four threads connected to each hook, resulting in a fabric that is warp ends wide with four repeats of the weave going across.
The term "Jacquard loom" is somewhat inaccurate. It is the "Jacquard head" that adapts to a great many dobby looms that allow the weaving machine to then create the intricate patterns often seen in Jacquard weaving. Jacquard looms, although relatively common in the textile industry, are not as ubiquitous as dobby looms which are usually faster and much cheaper to operate.
However, unlike jacquard looms, they are not capable of producing so many different weaves from one warp. Modern jacquard looms are controlled by computers in place of the original punched cards, and can have thousands of hooks. The threading of a Jacquard loom is so labor-intensive that many looms are threaded only once. Subsequent warps are then tied into the existing warp with the help of a knotting robot which ties each new thread on individually.
Even for a small loom with only a few thousand warp ends the process of re-threading can take days. Originally the Jacquard machines were mechanical , and the fabric design was stored in a series of punched cards which were joined to form a continuous chain. The Jacquards often were small and only independently controlled a relatively few warp ends. This required a number of repeats across the loom width. Larger capacity machines, or the use of multiple machines, allowed greater control, with fewer repeats, and hence larger designs could be woven across the loom width.
A factory must choose looms and shedding mechanisms to suit its commercial requirements. As a rule the more warp control required the greater the expense. So it is not economical to purchase Jacquard machines if one can make do with a dobby mechanism. As well as the capital expense, the Jacquard machines are more costly to maintain, as they are complex and require higher skilled personnel; an expensive design system is required to prepare the designs for the loom, and possibly a card-cutting machine.
Weaving is more costly since Jacquard mechanisms are more likely to produce faults than dobby or cam shedding. Also, the looms will not run as quickly and down-time will increase because it takes time to change the continuous chain of cards when a design changes. For these reasons it is best to weave larger batches with mechanical Jacquards.
It is recorded that in a Frenchman  adapted the Jacquard mechanism to a system by which it could be worked by electro-magnets. There was significant interest, however trials were not successful, and the development was soon lost in history. Bonas Machine Company Ltd. Although the machines were initially small, modern technology has allowed Jacquard machine capacity to increase significantly, and single end warp control can extend to more than 10, warp ends. This avoids the need for repeats and symmetrical designs and allows almost infinite versatility.
The computer-controlled machines significantly reduce the down time associated with changing punched paper designs, thus allowing smaller batch sizes. However, electronic Jacquards are costly and may not be required in a factory weaving large batch sizes, and smaller designs.
The larger machines allowing single end warp control are very expensive, and can only be justified where great versatility is required, or very specialized design requirements need to be met.
For example, they are an ideal tool to increase the ability and stretch the versatility of the niche linen Jacquard weavers who remain active in Europe and the West, while most of the large batch commodity weaving has moved to low cost areas. Linen products associated with Jacquard weaving are linen damask napery, Jacquard apparel fabrics and damask bed linen.
Jacquard weaving of course uses all sorts of fibers and blends of fibers, and it is used in the production of fabrics for many end uses. Research is under way to develop layered and shaped items as reinforcing components for structures made from composite materials. The Jacquard head used replaceable punched cards to control a sequence of operations.
It is considered an important step in the history of computing hardware. Charles Babbage knew of Jacquard looms and planned to use cards to store programs in his Analytical Engine. In the late 19th century, Herman Hollerith took the idea of using punched cards to store information a step further when he created a punched card tabulating machine which he used to input data for the U.
A large, punched-card-based data processing industry developed in the first half of the twentieth century, dominated by the International Business Machine corporation IBM , with its line of unit record equipment.
The cards were used for data, however, with programming done by plugboards. Some early computers, such as the IBM Automatic Sequence Controlled Calculator Harvard Mark I received program instructions from a paper tape punched with holes, similar to Jacquard's string of cards.
Later computers executed programs from higher-speed memory, though cards were commonly used to load the programs into memory.
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Other articles where Jacquard weave is discussed: weaving: Jacquard weaves, produced on a special loom, are characterized by complex woven-in designs, often with large design repeats or tapestry effects. Fabrics made by this method include brocade, damask, and brocatelle. What is a jacquard weave and why is it so unique? A jacquard weave is created through a loom process, which is programmed to raise each warp thread independently of the other threads. The design of the textile is incorporated into the weave, instead of being printed or dyed onto the fabric. Jacquard weave definition is - an intricate variegated weave made on a jacquard loom and used for brocade, tapestry, and damask.
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