Basic Concept of Yarn Count, Yarn Diameter and Yarn Composition

Yarn count, yarn diameter and yarn composition are important parameters of yarn. In this article I will discuss basic concept of these parameters of yarn.

Yarn Count:
Yarn count is a numerical expression which defines its fineness or coarseness. It is an important parameter of yarn. Higher count will be more thin yarn and course yarn low count. A characteristic measure to classify fibers and yarns is given by the linear density, which defines the mass of polymer per length of fiber or yarn. Different systems for linear densities are in use; their use depends on the material and region.

yarn diameter
Fig: Different colored yarns

Knowledge of yarn count is important for the following purposes:

  1. To specify or identify a yarn.
  2. To place order for procurement of yarn from spinning department,
    stores, etc.
  3. To buy or sell yarn, i.e., trading of yarn.
  4. To utilize yarns during knitting, weaving and other processes according to requirement.
  5. To find out the weight of the product at any process.
  6. To set machine speed and other settings.
  7. To select machine gauge and other relevant machine parts.
  8. To allot processing units/machines to the operators.
  9. To gather knowledge on the content of yarn in any package.

Yarn Diameter:
Yarn diameter helps to determine how closely the yarns can be packed to make a fabric or how well a given yarn will cover in a given fabric. Although yarn count serves the purpose of defining yarn fineness, i.e., yarn diameter for general textile processing, sometimes it is essential to calculate the exact diameter of the yarn.

In certain applications, yarn fineness expressed in diameter or thickness provides more useful information. For example, determining the structural features of a fabric (e.g., cover factor, yarn crimp, etc.) requires a prior knowledge of yarn diameter. It is important, therefore, to measure yarn diameter or to provide an estimate of its value.

Yarn diameter is used to estimate fabric structural parameters such as width and cover factor. Since thousands of ends or wales are presented side-by-side in the woven or the knit fabrics, a slight change in yarn diameter can result in a substantial change in the overall cover factor of fabric. Factors affecting yarn diameter are essentially those that affect yarn density or fiber compactness.

For a given yarn count and at the same twist factor, the larger the fiber length, the higher the yarn density and the smaller the yarn diameter.

Calculation of yarn diameter is specially needed in the following cases:

  1. To set slub catcher or yarn clearer in winding.
  2. To determine beam width, reed count, etc., in warping, sizing and weaving.
  3. To decide number of threads per inch in cloth.
  4. To decide needle size or machine gauge in knitting.
  5. To study fabric geometry.

Considering the importance of yarn diameter, attempts were made to establish the relationship between diameter and count of yarn. In this respect, the pioneering work of Pierce is praise worthy. As derived by him, the approximate diameter (d) of cotton yarn,

d in inch = 1/{28 × √(count)}
or d in mm = 0.0037 × √(Tex)

For the purpose, he assumed specific volume of cotton yarn as 1.1 (i.e., 1.1 c.c. of cotton yarn weighs 1 g).

Table: Formula for measuring yarn diameter

Formula for yarn diameter

Yarn Composition:
As classified earlier, any yarn may be made of either only one type of fiber or two/more types of fibers. Moreover, the fiber making the yarn may be staple or filament type. So, the fiber used in making the yarn is very much important in deciding the properties of the yarn as well as the end use of the same. A brief classification of the commonly used fibers is discussed in the under-going. All the fibers available in the world are first classified as natural fibers (obtained from or gifted by the nature) or manmade fibers (made/developed by human being). Further, both natural and man-made fibers can be classified into various categories according to the source, origin or composition of the fiber as shown in Table.

Table: Classification of yarns based on fiber composition

Natural fibers Vegetable fibers Seed fiber (cotton)
Bast fiber (jute, hemp, flax)
Leaf fiber (sisal, pineapple)
Animal fibers Wool
Silk
Mineral fibers Asbestos
Glass
Man made fibers Regenerated fibers Viscose
Acetate
Tencel
Synthetic fibers Polyamide (Nylon)
Polyester
Polyacrylonitrile (Acrylic)
Poly-propylene
Polyurethane (Spandex)

Each type of fiber has their peculiar properties and found suitable for specific end uses. Previously, cotton and wool out of many natural fibers were used in weft knitting and nylon and polyester out of different man made fibers were mainly used in warp knitting. But nowadays due to advent of modern machinery and technology in one hand and product diversification on the other, many other fibers along with those four fibers have found place in knitting. Jute, the coarse and harsh fiber, even can be knitted for using as agricultural textiles and surface ornamentation of outer garments having very good demand in the market. The physical and chemical properties of all fibers are not same but vary from fiber to fiber.

Some of the important properties of fibers considered for using in knitting are given below:

  • Strength
  • Durability
  • Stretchability
  • Bending rigidity
  • Dye affinity
  • Skin friendliness
  • Moisture content
  • Brightness
  • Thermal insulation

So sometimes two or more fibers are mixed or blended together for producing the knitting yarn to accomplish desired –

  1. Physical properties,
  2. Aesthetic effect,
  3. Cross-dye effect and
  4. Economical production.

Spandex (Lycra) yarn in certain proportion is used with other yarns to make the fabric more stretchable and elastic as well as to impart better form fitting properties.

You may also like:

  1. Yarn Count Numbering System and Conversions
  2. Determination of the Yarn Count by Wrap Reel and Analytical Balance
  3. How to Determine Thread Count of Fabric by Beesley Balance
  4. Yarn Count Measurement System
  5. Count Conversion System for Textile Yarns
  6. Understanding Yarn Count | Yarn Counting System
  7. Relationship between Yarn Count and Twist | Principles of Twist Measuring Methods

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