Yarn Tests | Determination of Yarn Count, Evenness, Tensile Strength, Twist and Abrasion Resistance Test

Different Yarn Tests:
The important yarn tests are given below:
  1. Determination of Yarn Count
  2. Determination of Yarn Evenness
  3. Tensile Strength Testing
  4. Twist Testing
  5. Abrasion resistance
Determination of Yarn Count:
To determine the yarn count of a sample, it is needed to measure the length and weight of the sample. The equipment used for this purpose are Wrap reel and Analytical balance or Knowles balance or Quadrant balance etc. Beesley's balance can be used to get the yarn count directly from the balance. When yarn specimen supplied is not sufficient to perform the tests on the above methods, Beesley's balance can be used to examine the yarn count with reliability. 

Determination of Yarn Evenness:
The surface irregularity of yarn is of particular importance in relation to processing properties, as even with a well maintained mean count, the appearance of the fabric can sometimes be affected considerably. Yarn evenness is assessed basically by deriving either the variation along the length of a yarn in the mass per unit length (or number of fibers per cross-section) or the variation in diameter. Visual evaluation and electronic methods are used for this purpose.

Tensile Strength Testing:
Particular importance is often attached to the tensile strength attained in a single or folded yarn of particular type and composition. Yarn extension also plays a considerable role in the processing of the yarn and in the end-use properties of the fabric produced. The range of instruments which are available for testing the strength of yarns is quite wide e.g. Single -thread testers operating on the principles of pendulum lever, inclined plane, Strained gauge, and Constant-tension hank testers of the pendulum lever or Ballistic type. Some of these instruments are relatively simple, some complicated, some have recording devices, and some are automatic. The choice of the best type to use is often difficult. Strength testing deals with the finding of load-elongation curve or stress-strain curve and breaking point or stress etc.

Twist Testing:
Generally, the Twist tester is used to determine the number of twist per unit length or tpi manually.

Yarn twist tester
Fig: Yarn twist tester
Abrasion Resistance:
Abrasion resistance is the ability of a fiber to withstand the rubbing or abrasion it gets in everyday use. This property of yarn plays an important part in its processing e.g. it determines the friction occurring on thread guides. A measurement of abrasion resistance is the number of cycles required to break the test specimen at a given initial tension. 

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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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