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Sunday, February 18, 2018

Weaving Loom Classification

Weaving Loom:
The loom is a device or machine in which interlacement of warp and weft yarn performed and thus fabric is produced. Loom is the principle mechanical device for weaving. The basic function of a loom is only making fabric. For manufacturing of fabric different types of loom are used in weaving industry.

Classification of Looms:
The weaving loom can be classified based on shed opening system or weft insertion system, which are explained in the following section.

With respect to picking mechanism:
Weaving loom classifications with respect to picking systems are shown in Figure-1.

Figure-1: Weaving loom classifications with respect to picking systems
The weaving looms are mainly classified into two distinct categories depending on the type of picking or weft insertion system. These cate­gories include shuttle loom and shuttleless loom. The shuttle loom car­ries a shuttle to insert the weft. The shuttle is comprised of wooden body having a weight of 150–250 grams and a pirn required to wind the weft yarn on it. The pirn is placed inside the wooden body of shuttle. The limi­tations of shuttle loom are its low speed, heavy weight, and extra stop­page due to empty pirn replacement. The shuttle looms are being rapidly replaced by shuttleless looms. The shuttleless looms are further classified into distinct categories including projectile loom, rapier loom, air-jet loom, and water-jet loom. All the possible weft insertion systems are shown in Figure-2.
Weaving loom weft insertion media
Figure-2: Weaving loom weft insertion media.
With respect to shedding mechanism:
The weaving looms are classified into three distinct categories depending on shedding mechanism: tappet loom, dobby loom, and jacquard loom. A summary of weaving loom with respect to shedding mechanism is given in Table-1. In tappet loom, the healed frames are operated with the help of tappet cams, which are designed according to weave designs. The advan­tages of tappet loom are simple mechanism, low initial cost, and easy main­tenance. The number of cams, in tappet loom, depends on the weave repeat, for example, 4 cams for 3/1 twill. The limitations of tappet loom are; tappet cam designed for one weave cannot be used for other weave and long time is required for cam change. In dobby looms, the healed frames are operated by jacks and levers, and lifting and lowering of healed frames are controlled by pattern chain.


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Table-1: Summary of Weaving Looms with Respect to Shedding Mechanism

Sr. No.
Type of Loom
Repeat Length (max.)
Number of Harness (max.)
Pitch (mm)
1
Tappet (positive and negative)
Up to 8 picks
12
18
2
Dobby (positive mechanical)
6000
28
12
3
Dobby (negative mechanical)
150
16
12
4
Dobby (rotary mechanical)
4700
28
18
5
Dobby (negative electronic)
6400
16
12
6
Dobby (positive electronic)
6400
28
12


Number of Hooks


7
Jacquard (single lift mechanical)
600


8
Jacquard (double lift mechanical)
1200


9
Jacquard (double lift electronic)
Up to 14,000


 
The dobby looms can be equipped with a maximum of 32 healed frames, which expands the weave design possibilities. The weave designs such as crepe, honey comb, huckaback, mockleno, and bedford cord are possible with dobby looms. However, mechanism is complicated as compared to tappet loom, and initial cost and maintenance cost are high. In jacquard loom, the warp yarns are individually controlled by a cord called harness cord rather than healed frame. The jacquard loom further expands the weave design possibilities to an unlimited extent. The woven cloth with complicated designs such as animals, flowers, and geometrical figures can be produced. A summary of available jacquard systems from Staubli is given in Table-2.

Table-2: Summary of Staubli Jacquard


Sr. No.
Application
Recommended Jacquard (Staubli)
Number of Hooks
Characteristics
1
Ribbons and labels
CX 182/LX 32/LX 62
192/448/896
Needle weaving, narrow fabrics, double-lift open-shed jacquard machine with crank drive, inclined shed on LX range
2
Written selvedges
CX 172
64 or 80
Labeling and logos on selvedges, double-lift open-shed jacquard machine, crank shed movement, parallel shed
3
Fabric inscriptions on selvage
CX 182
96 or 192

4
Flat fabrics and terry cloth
LX 1602 and LX 3202
LX 1602: 3072, 4096, 5120 hooks
LX 3202: 6144, 8192, 10240, 12288(x2), 14336, 18432 hooks
Flat fabrics, terry cloth, and technical fabrics, double-lift open-shed jacquard machine, Coaxial shaft system, controlled by complementary cams, Fine adjustment of shed opening and shed angle


SX
1408 hooks (11 rows of 16 modules)
2688 hooks (21 rows of 16 modules)
Flat fabrics and terry cloth, 76 precise, accessible shedding settings
5
Labels and name selvedges on fabric

UNIVALETTE
64 or 96 actuators per head
Labeling and logos on selvedges and in all flat fabrics, the jacquard machine has its own drive with no mechanical link to the weaving machine and is electronically synchronized
6
Free of mechanical constraints
UNIVAL 100
512–15360(x2) threads with all intermediate formats
Flat fabrics, terry cloth, technical fabrics and carbon fiber fabrics, individual warp thread control with Stäubli JACTUATOR, the jacquard machine has its own drive with no mechanical link to the weaving machine and is electronically synchronized
7
Velvet fabrics

SX V

2688 hooks

Velvet fabrics, two parallel shafts, cam driven on both sides


LX 1692,

3072, 4096, 5120 hooks
Coaxial shaft system, controlled by complementary cams


LX 3292
6144, 8192, 10240, 12288, 14336 hooks
Fine adjustment of shed opening and shed angle