Specification of Yarn | Quality and Parameters of Yarn

A generic term for a continuous strand of textile fibers, filaments, or material in a form suitable for knitting, weaving, or otherwise intertwining to form a textile fabric. Yarn occurs in the following forms: (1) a number of fibers twisted together (spun yarn); (2) a number of filaments laid together without twist (a zero-twist yarn); (3) a number of filaments laid together with a degree of twist; (4) a single filament with or without twist (a monofilament); or (5) a narrow strip of material, such as paper, plastic film, or metal foil, with or without twist, intended for use in a textile construction.
Yarn quality
Fig: Yarn quality
Parameters of Yarn are Mentioned below:
1. Yarn Appearance:
The Visual Effect obtained by viewing a sample of yarn wound with a designated traverse on a black board of designated size.

Nep: A tightly tangled mass of unorganised fiber

Slub: An abruptly thickened place of yarn

Thick place: A yarn defect where the diameter is greater than the adjoining segments and extending for 6 mm

Thin Place: A yarn segment where the diameter is 25% lesser than the average diameter of yarn

Fuzz: Untangled fibers that protrude from the surface of the yarn

Bunch: A yarn segment not over 6 mm in length that shows abrupt increase in diameter caused by more fibers matted in this particular place

Method: Yarn wound on hylam black boards wound for fixed wraps per inch as per count compared with standard reference boards.

Grades: Above ‘A’ to below ‘D’ - The imperfections increase from Grade ‘A’and the maximum in grade ‘D’. Average index of five boards of five graders.

2. Yarn Evenness:
Unevenness: Variation in the linear density of a continuous strand or of a portion of as trand.

Apparatus: Uster–Evenness Tester

Principle: Difference in the capacitance variation. Lower the Count lower the Imperfections. One km of yarn is run through two capacitance plated at specific speed (fixed as per the count). The capacitance variation is integrated and expressed as % unevenness (U%). The imperfections are counted and are reported per kilometer.

3. Linier Density of Yarn:
Expression of the fineness of yarn
A number indicating the mass per unit Length or the length per unit mass of Yarn

Direct system: Denier, Tex (Weight Of Unit Length)
Indirect System (Units of Lengths) per (Units of weights)

4. Count Test
  • Wrap reel
  • Balance
120 yards of yarn / 100 meters of yarn wound in a wrap reel and weighed .
From the weight, the count is calculated.

5. Single Thread Strength Testing
Force Required to break a single strand of yarn of unit length

Apparatus - Single thread Strength Tester
RKM %Elongation

6. Lea Stength Testing
Lea Breaking Strength
The Force required to break one lea
Unit –pounds
Count Strength Product
Apparatus Lea Tester

7. Principles Of Tensile Testing
Constant Rate of Loading: The Rate of change of Load is constant – Uster Dynamat
Constant rate of Traverse: The pulling clamp moves at a constant rate – Lea – Pendulum tester
Constant rate of Extension: Rate Of change of Specimen length is constant – Statmat

8. Twist Testing

Direction Twist
S –Twist: When Held in vertical position, the spiral confirm in slope to the central position of the letter ‘S’
Z –Twist: When Held in vertical position, the spiral confirm in slope to the central position of the letter ‘Z’

No of Turns (Twists) per Unit length
Single Twist
Double Twist
Twist Multiplier

Apparatus: Twist Tester
Direct Method
Indirect Method
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Mazharul Islam Kiron is a textile consultant and researcher on online business promotion. He is working with one European textile machinery company as a country agent. He is also a contributor of Wikipedia.

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