Yarn Clearer and it's type

YARN CLEARER

Some faults are usually generated in spun yarn during spinning. It’s necessary to eliminate these yarn faults at winding yarn clearing refers to the process of fault elimination

Types of Yarn Clearer

• Mechanical type
• Electronic type

Mechanical Type

Mechanical yarn clearer work on two basic principle

1. Fixed or parallel blade type yarn clearer
2. Swinging blade type or trap clearer

Fixed Blade or Parallel Blade Type of Mechanical Clearer

• The yarn is passed between two metal blades separately by a narrow gap.
• The gap between two blades forma slit through which the yarn is made to pass during winding.
• The thick place in the yarn gets jammed between the blades and yarn breaks.
• The distance between two blades depends upon the yarn diameter, type of yarn and the degree of clearing required.
• For proper must be parallel to each laying in the same vertical plane without or bow- shaped face.

Swinging Blade Type or Trap-type Clearer

• Which consist of a pivoted slanting spring loaded blade. A fixed plate platform or rod lies beneath the blade an adequate clearance lies between blade and platform to pass regular yarn pass through it.
• A thick place in the yarn pushes the blade and forces in to make in the direction running yarn.
• This close the opening between blade and platform for the yarn to pass through to break the yarn.
• The gap between edge of the blade and platform range between 3 and 5.5 times yarn diameter depending upon yarn & type of blade.

      Mechanical yarn clearer are cheap, robust and easy to maintain. Most of thick places can get squeezed and pass through the clearer without braking. As the yarn contact blade edges it gets abraded with the clearer blade. It can liberate dust, fly, etc…. and May increase the yarn hairiness.

Electronic Yarn Clearer

     Electronic yarn clearer detect yarn faults using electronic principle and therefore are capable of eliminating a when spectrum of yarn faults very efficiently.

       Sensors for detecting mass diameter deviation. Two principle are used for detection of deviation of yarn diameter mass.

• Optical
• Capacitance

In an optical electronic yarn clearer a photo cell is used. A source of light causes light to be incident on photocell and generates emf. The yarn is made to pass between the source of light and photocell which interrupts the beam of light and therefore lower the emf generated change in emf indicate variation in yarn diameter.

The area of shadow cast by a flat elliptical Slub depends upon it’s orientation with respect to direction of beam as shown.

If flats portion is oriented along direction of beam of beam of light, area of shadow cast would be less and the Slub May escape detection. If faults are scanned from more than one direction, this error can be avoided.

In the capacitance clearer, the yarn pas through on air filled condenser. The capacitance of this condenser change with the mass of material between the plates. Thus change in capacitance indicate mass of material passing between the plates of condenser of given instant.

The capacitance of the capacitor depends upon the mass of the yarn as well as the dielectric of fiber.

E = Dielectric constant

A = area

D= distance between two plates

Textile fiber are hygroscopic the absorption of moisture may bring above a large change in dielectric constant because dielectric constant of water is very high.

REF: - fundamentals of yarn winding by Milind Koranne (Woodhead Publishing India in textile)

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