Determination of fiber fineness of cotton yarn by Sheffield micronaire instrument.

Experiment No: 06

Experiment Name: Determination of fiber fineness of cotton yarn by Sheffield micronaire instrument.

Introduction:

Fiber fineness determines how many fibers are present in the cross-section of a yarn of a given thickness. Minimum 30 fibers are needed in the yarn cross section but there are usually hundred. Fiber fineness is expressed in micronaire value.

Objectives:

(1) To determine regular and irregular fiber to making fine or coarse yarn.

(2) To make uniform yarn.

(3) To make good appearance fiber fineness is measured.

Machine description:

Sheffield micronaire is an instrument based on air flow principle. Air from a compressor is supplied to this instrument. The fest pedal is present to allow the air flow. The pressure of air is noted from the pressure gauge. An air filter is incorporated incline to filter the dust particles. The air is divided into the stream at the point x. One stream passes through the flow meter. The other passes through the perforations through the fibers in fiber camber and through the hole of the plunger to the atmosphere.

Working principle:

The rate of air flow is inversely proportional to the surface area of the fibers. A sample of known weight is compressed in a cylinder and subjected to an air current at a known pressure. The rate of an air flow through this process plug of fibers, related to the fineness of cotton fiber is measured.

Working procedure:

(1) At first we take 3.24 grams sample.

(2) The sample is opened very well to remove the dust.

(3) Then the sample is introduced into the compression chamber.

(4) The fiber compression plunger is inserted and locked in its place twisting the compresses the                sample into a process plug of fiber.

(5) The foot pedal is operated to allow air inside and reading is taken.

(6) Then foot pedal is operated to shut off the air flow. Then the sample is removed from the                       compression chamber.

(7) After that we get the micronaire value of that fiber. Take at least five value.

(8) Calculate average value and rating the fiber.

Calculation:

For observation 1,

Micronaire value = 3.5

For observation 2,

Micronaire value = 3.4

For observation 3,

Micronaire value = 3.5

For observation 4,

Micronaire value = 3.5

For observation 5,

Micronaire value = 3.4

Average micronaire value is 3.46

Table:

Observation no.	Micronaire value	Average value	Fiber rating
1.	3.5
2.	3.4
3.	3.5	3.46	Fine
4.	3.5
5.	3.4

Result:

From this average value we can say that this fiber is fine.