IMPORTANT PARTS OF LOOMS ( HEALDS)
Some very important parts of looms:-
Earlier I have explained the normal parts which are used in weaving. Here I am going explain about some important part (in detail) which are necessary to improve the quality of the cloth (textile).
They are ;-
1) Heald.
2) Reed and
3) Temples.
(1)HEALDS:-
NECESSITY OF HEALD:-
The care fully arranged warp wound upon a warp must be divided into two layers to form a shed for the interlacement of longitudinal and traverse threads in a fabric. Healds are required to form this shed. The proper selection of the warp threads are in successive picks of a repeat of the pattern forms the design of a fabric. In modern looms the warp threads are placed in horizontal line from back to front. This has been made possible to the invention of healds. Before the use of healds were known the warp threads had been placed vertically and the weaving was done by means of 'shed sticks'.
TYPES OF HEALDS:-
Various types of heald have been tried and used during many centuries past, of which the last four below are now used in handlooms and powerlooms. Although, the art of weaving had been known thousands of years ago, yet little effort were made either towards improvement in the quality of a heald or towards mechanisation of a loom. The quality of cloths manufactured, however did not lack in decorative pattern, color displays, fineness or beauty . Some of the ancient and modern healds are as following:-
(i) Primitive healds:
(ii) Single-clasped healds:
(iii) Double-clasped healds:
(iv) Eye healds, cotton , worsted, etc:
(v) Healds with mail eyes or metallic clips: (vi) Wire healds: and
(vii) Doup healds.
Cotton varnished healds round or flat wires healds and Doup healds are now commonly used in the industry.
PRIMITIVE HEALDS:-
The first primitive heald which was used in a horizontal loom consist of a series of twine loops each passing round a warp and fastened to a wooden rod . The number of loops on a rod and the number of rods employed depends upon the breadth and closeness and cleaness of warp threads.
In fig. 1, the dots A are cross-section of warp threads , B is the twine formed into loops , and on top is the wooden rod to which the loops are attached. When the rod is drawn forward, all warp threads controlled by it will be carried in advance by those operated by the other rod.
Single-clasped Healds:-
Single-clasped healds consist of passing two series of threads into separate rods. The warp threads are kept in proper order and there by the production of the loom is increased largely, as shown at fig. 2
It is desirable to leave the threads free to slide in the heald when an upward or downward movement is given to them, but with clasped heald this cannot be done. Where weak or in elastic warps are used excessive breakages result forming shed in this manner.
Double-clasped healds:- The first change consisted in doubling the number of loops on each pair of rod and in causing those loops to lie in two ranges. A warp thread was then passed over one loop and under another, so that was as the roda rose or fell , the warp was positively moved without undue strain as illustrated in fig.3
The next improvement in the method of production of a shed led to the invention of modern healds , such as , eyed healds , wire etc.
EYED HEALDS:-
The eyed healds consist of knitted eyes about the middle of the twine . Fig. 4 shows an eyed heald. B and B' are loops which for cotton manufacturing vary between 10" and 14" or 25.4 cms and 35 cms. from the top to bottom. C is an eye whose depth is 1/4" or 0.635 cm. fit cotton goods and 3/8" or 0.95 cm. for silk goods. D and D' are the laths or shafts (fig.4 and 5).
Eyed healds are made of different lengths, diameters and sizes of loops and of varied materials. Worsted, linen, silk, cotton, iron and steel amongst other materials have been used to make healds , but cotton , steel worsted, are now chiefly employed . Uptil the first quarter of this century worsted was the principal Heald twine used in the cotton and silk weaving
industry but cotton healds have now entirely dependent superseded the worsted , because they are cheaper and work better as well as last longer than worsted . Many cotton eyed heald are entirely made of twine, and are varnished to withstand wear and the humidity of the atmosphere in the power loom shed.
GLASS OR METAL-EYED HEALD:-
Eyed healds some times support steel, brass , glass or other metal eyes , as fig.6. Such healds are usually employed when rough, knotty warps have to be woven , but glass is principally used for silk and occasionally for cotton gauze . They all offer less resistance to the passage of warp than twine eyes and wear better: but they usually take more room.
HEALDS YARNS:-
Machine made healds have superseded the hand-made varieties. The highly developed knitted-heald industry uses such yarn as a worsted, silk linen and cotton . The quality of sizing and varnishing the healds have greatly improved . Good quality of material and skilled workmanship are necessary to make good healds, otherwise the latter may be source of a lot of troubles in the loom, such as , swollen and twisted twine, eyes closed or sideways to warp instead of open and racing it roughness , limps of size and varnish in the eyes, rigidity, stickiness and lack of lasting properties. Healds should be flexible smooth , capable of resisting friction and strain and readily adjustable to any reed or pattern.
The cotton twine , of which healds are made in should vary in thickness and strength to suit the warp it has to actuate. Cotton healds are manufactured with various counts of yarn but thicker foldings will make make strong healds, through they are more costly .
COUNTS OF HEALDS:-
There are four healds in a set . The counts of healds indicate the number of Heald eyes on one inch or 2.54 cms. across all the healds in a set . In 40" healds each of the four shafts will have 10 eyes per inch or 2.54 cms. Wire healds are bought in bundles of 1000 , stave being separate.
Ref:-Weaving Mechanism Book Vol. I by Prof. N. N. Banerjee.
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