Notes on Yarn for Rope Dyeing in Denim

Notes on Yarn for Rope Dyeing

* Yarn faces stress and stretch at ball warping, rope dyeing, rebeaming, sizing and loom shed so elongation of yarn should be more than stretch at (ball warping + Robe Dyeing+ Rebeaming + Sizing )= (2-3%) + Loom shed (about 5%)

* Tension at Ball warping should be less by 7-8% of single yarn strength.

* Strength CV should be within limits as it may give rise to weak points

* The tendency of yarn to migrate at rope dyeing can be countered by less micronaire of yarn ( should be around 3.8-4.2)

* More dropping of short fibers at long chain beaming is good

*The sensitivity settings for neps is set at +280 for rotor spun yarn and not +200 as in case of ring spun yarn. The reason for this is that the structure of rotor spun yarn is intrinsically different from that of conventional ring spun yarn. Neps in rotor yarn tend to be spun into the solid yarn body rather than remaining on the yarn surface, which is typical of ring spun yarns. Although embedded in the yarn core, these neps still represent a short mass defect and will therefore trigger the imperfection counter upon exceeding the preset value. However, compared to neps that are attached to the yarn surface, fully embedded neps are barely perceptible for the human eye. Thus, in order to balance the typical visual appearance of rotor spun yarn with the imperfection counts, +280 sensitivity setting is a common convention for rotor spun yarns.

Comparison of Ring Yarn with OE yarn at Ne 7

Denim Manufacturing Process- the presentation

Please refer to the following presentation for the denim manufacturing process

Proposed Inspection Process for Indigo Dyed Denim

* A four point system can be adopted, with 9 qualities ( from 9 to 1).

The point distribution is as follows:

upto 3"= 1 point
3-6"= 2 point
6-9"= 3 points
9" and above= 4 points

Any defect across full width = 4 point
All the above defects may be length or width wise.
Length wise one course or fine ends/ up to one meter=4
Starting mark (across the width)=4
Cuttable Defects
-moire
- continuous slub or slubbing weft
- thinck end more than one meter
- major shade variation
-burnt selvedge
- blanket impression
-width variation
-Jala-jerky-chira-wrong drawn- float-snarls-missing ends- more warp breaks- patti-holes-cuts-sever temple mark- more pick findings in short length, double pick
-Slack and tight ends >1m


* From qualities 3-9, only 2 pieces in a single roll are allowed and no piece should be less than 30 meters.

The qualities Criterian can be defineds as follows:

9--> 2 shades allowed, allow 20 points per linear meter which no greater than 2 to 3 4 points defects
8--> 3 shades are allowed, allow 36 points per linear meter no greater than 4, 4 point defects
7--> same as 8 but here we allow upto 5 shades
6--> Allow 72 points per linear meter, upto 3 shades -no greater than 5 to 6 , 4 point defects
5--> same as 6, but 5 shades are allowed.
4--> points should not be greater than 72, any number of shades, any number of 4 point defects. We do not allow patta ( width wide strips)
3--> Same as 4, we can allow patta
2--> same as 3, 5 pieces are allowed ( every piece 10-30 meters each)
1--> any continuous defect is allowed ( pack the piece less than 1 meter)

Shade gradation can be
Dark Shade--> D+
Normal Shade --> D
Light Shade --> D-

Relation between Manual and "l a b" grading system
l, a, b values
D- = 554,654,655
D= 454,555,656
D+= 455,456,556

Tolerance for l a b values--> L = +-0.5, a = +/- 0.5, b= +/- 0.5

Voile, Cambric, Terry voile, shiffon, long cloth, classical oxford, pin-point oxford, Chief Value Cotton

Voile

It is a doubled yarn, highly twisted with count range >60s. It has an square and open construction. The fabric made from it is light weight, transparent, crispy and granular feel. It can be either cotton or P/C. Its trade name is 2 x2 Rubia. 72 epi and 72 ppi.

Cambric

It is a single yarn, rest properties are same as voile.

Terry Voile

It is name of voile with 2/81 high twisted fabric in 67:33 blend which is later carborised to get a 100% polyester fabric.

Shiffon

Count is 62s. Here weft is highly twisted (1400-1500 tpm) polyester filamnet and textured and warp is p/c. 67:33

Long Cloth

It is a plain fabric with special kind of finish which remains for some times even after normal washing.

Poplin Broad Cloth
A tightly woven, subtle variation on a plain-weave fabric, characterised by a very high thread count- 100 to 200 tpi- produces a thin, but relatively opaque fabric with a crisp, hard finishing. Also characteristics of the fabric is its fine horizontal ribbing, produced by the lengthwise warp threads being packed more densly than the crossing weft threads. The ribbing is scarcely noticeable but makes any on-grain stripes very clear and appear solid in color, and it also adds a little shine on the fabric. If the cotton fiber itself has any shine, it will enhance the shine of ribbing and produces a very dressy effect. It comes in solid colors, stripes, plaids and checks.

120 *72
Chambray: It looks solid color but is a plain worked with two colors of yarns, usually a white warp and a colored weft or vice-versa. They are woven in all weights. It can be poplin, or twill or dobby chambray

Classical Oxford
It is like chambray, but in contrast to a chambrays plain weave, oxford cloth is woven in a basket weave. It produces the fabric's soft bulkiness.

Warp is Dyed and weft grey
warp --> 2/40s, Weft --> 2/30s

Pin Point Oxford
When worked in a fine weave, oxford cloth is called a pinpoint oxford.

both warp and weft 2/80s, 144 ends/inch in grey and 60-62 ppi.

Chief Value Cotton

60% cotton, 40% polyester

German Finish

Enzyme treatment. Here fabric gets very good lustre and feel. Also we do a process called weight reduction process ( weight is reduced by 4-5%, so bulkiness in the fabric is given.

Chinos

3/1 twill with 2/40s * 2/30s. When single yarn is used it is called Drill.

Gaberdine
2/1 twill
with 2/40s * 2/30s