COTTON AND YARN QUALITY CO-RELATION:
Instead of buying any cotton available at lowest price, spinning it to produce yarn of highest count possible and selling Yam at any market in random, it is advisable to locate a good market where Yarn can be sold at highest price and select a Cotton which has characteristics to spin Yarn of desired specifications for that market.
ESSENTIAL CHARACTERISTICS of cotton quality and characteristics of Yarn quality of Yarn are given from detailed experimental investigations. Some of the important conclusions which help to find co-relation between Yarn quality and Cotton quality are given below
- STAPLE LENGTH: If the length of fiber is longer, it can be spun into finer counts of Yarn which can fetch higher prices. It also gives stronger Yarn.
- STRENGTH : Stronger fibers give stronger Yarns. Further, processing speeds can be higher so that higher productivity can be achieved with less end-breakages.
- FIBER FINENESS: Finer Fibers produce finer count of Yarn and it also helps to produce stronger Yarns.
- FIBER MATURITY : Mature fibers give better evenness of Yarn. There will be less end - breakages . Better dyes' absorbency is additional benefit.
- UNIFORMITY RATIO: If the ratio is higher. Yam is more even and there is reduced end-breakages.
- ELONGATION :A better value of elongation will help to reduce end-breakages in spinning and hence higher productivity with low wastage of raw material.
- NON-LINT CONTENT: Low percentage of Trash will reduce the process waste in Blow Room and cards. There will be less chances of Yarn defects.
- SUGAR CONTENT: Higher Sugar Content will .create stickiness of fiber and create processing problem of licking in the machines.
- MOISTURE CONTENT : If Moisture Content is more than standard value of 8.5%, there will be more invisable loss. If moisture is less than 8.5%, then there will be tendency for brittleness of fiber resulting in frequent Yarn breakages.
- FEEL : If the feel of the Cotton is smooth, it will be produce more smooth yarn which has potential for weaving better fabric.
- CLASS : Cotton having better grade in classing will produce less process waste and Yarn will have better appearance.
- GREY VALUE: Rd. of calorimeter is higher it means it can reflect light better and Yam will give better appearance.
- YELLOWNESS : When value of yellowness is more, the grade becomes lower and lower grades produce weaker & inferior yarns.
- NEPPINESS : Neppiness may be due to entanglement of fibers in ginning process or immature fibers. Entangled fibers can be sorted out by careful processing But, Neps due to immature fiber will stay on in the end product and cause the level of Yarndefects to go higher.
An analysis can be made of Yarn properties which can be directly attributed to cotton quality.
1. YARN COUNT: Higher Count of Yarn .can be produced by longer, finer and stronger fibers.
2. C.V. of COUNT: Higher Fiber Uniformity and lower level of short fiber percentage will be beneficial to keep C.V.(Co-efficient of Variation) at lowest.
3. TENSILE STRENGTH : This is directly related to fiber strength. Longer Length of fiber will also help to produce stronger yarns.
4. C.V. OF STRENGTH : is directly related CV of fiber strength.
5. ELONGATION : Yam elongation will be beneficial for weaving efficiently. Fiber with better elongation have positive co-relation with Yarn elongation.
6. C.V. OF ELONGATION: C.V. of Yarn Elongation can be low when C.V. of fiber elongation is also low.
7. MARS VARIATION : This property directly related to fiber maturity and fiber uniformity.
8. HAIRINESS : is due to faster processing speeds and high level of very short fibers,
9. DYEING QUALITY : will defend on Evenness of Yarn and marketing of cotton fibers.
10. BRIGHTNESS : Yarn will give brighter appearance if cotton grade is higher.
COTTON QUALITY SPECIFICATIONS:
The most important fiber quality is Fiber Length
|Length mm||Length inches||Spinning Count|
|Short||Less than 24||15/16 -1||Coarse Below 20|
|Medium||24- 28||1.1/132-1.3/32||Medium Count 20s-34s|
|Long||28 -34||1.3/32 -1.3/8||Fine Count 34s - 60s|
|Extra Long||34- 40||1.3/8 -1.9/16||Superfine Count 80s - 140s|
- Spinning Count does not depend on staple length only. It also depends on fineness and processing machinery.
- Length is measured by hand stapling or Fibrograph for 2.5% Span Length
- 2.5%SL (Spun Length) means at least 2.5% of total fibers have length exceeding this value.
- 50% SL means at least 50% of total fibers have length exceeding this value.
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