Cotton Fibre
Staple Length
The most important fiber quality is Fiber Length
Staple classification | 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 |
Notes:
- Length is measured by hand stapling or Fibro graph for 2.5% Span Length.
- 50% SL means at least 50% of total fibers have length exceeding this value.
- 2.5%SL (Spun Length) means at least 2.5% of total fibers have length exceeding this value.
- Spinning Count does not depend on staple length only. It also depends on fineness and processing machinery.
Specifiaction
UR % Classification | Grade |
---|---|
50-55 | Very Good |
45-50 | Good |
40-45 | Satisfactory |
35-40 | Poor Below |
30 | Unusable |
Fiber Strength
Fiber Strength, next important quality is tested using Pressley
instrument and the value is given in Thousands of Pounds per Square
inch. (1000 psi) For better accuracy, Stelometer is used and results are
given in grams / Tex.
Lately, strength is measured in HVI (High Value Instrument) and result is given in terms of Grams/Tex. Interpretation of Strength value is given below.
Lately, strength is measured in HVI (High Value Instrument) and result is given in terms of Grams/Tex. Interpretation of Strength value is given below.
G/Tex | Classification |
---|---|
Below 23 | Weak |
24-25 | Medium |
26-28 | Average |
29-30 | Strong |
Above 31 | Very Strong |
Strength is essential for stronger yarns and higher processing speeds.
- Micronaire values vary from 2.6 to 7.5 in various varieties.
- Finer Fibers give stronger yarns but amenable for more Neppiness of Yarn due to Lower maturity.
- Fiber Fineness Fiber Fineness and maturity are tested in a conjunction using Micronaire Instrument.
- Spinning Count does not depend on staple length only. It also depends on fineness and processing machinery.
Micronaire for Fineness and Maturity
Usually Micronaire value is referred to evaluate fineness of Cotton and its suitability for spinning particular count of Yarn.
Cotton Grade
Evaluating colours, leaf and ginning preparation determine Cotton grade.
Higher-grade Cottons provide better yarn appearance and reduced process
waste.
Influences
S.No. | Quality Evaluation | Characteristics Co-Relation to Yarn |
---|---|---|
1 | Staple Length | Spinning Potential |
2 | Fiber Strength | Yarn strength, less Breakages |
3 | Fineness | Finer Spinning Potential |
4 | Maturity | Yarn Strength and even ness, better dyeing |
5 | Non-Lint. content (Trash) | Reduced Waste |
6 | Uniformity Ratio | Better productivity and Evenness |
7 | Elongation | Less end Breakages |
8 | Friction | Cohesiveness |
9 | Class | Yarn Appearance |
10 | Stickiness | Spinning problem by lapping & Dyeing quality |
11 | Grey Value | Yarn luster |
12 | Yellowness | Yarn Appearance |
13 | Neppiness | Yarn Neppiness |
14 | Moisture Content | 8.5% moisture content optimum for spinning at 65% |
Fiber Quality Testing Equipments
Instrument | Measurements |
---|---|
Fibro graph | Length |
Pressley Apertures | Fiber Bundle Strength |
HV I Instrument | Length, Strength, Uniformity, Colour, Elongation, Micronaire & Trash |
Stelometer Instrument | Strength, Elongation |
Micronaire | Combined test of fineness & maturity |
Shirley Trash Analyzer | Trash Content |
Manual Test | Class & staple length |
Moisture Meter | Moisture |
Colorimeter | Grey value & yellowness. Brightness |
Polarized light Microscope or Casricaire test | Maturity |
Photographic film | Neppiness |
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