COTTON FIBRE

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.

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

\