The purpose of this experiment is to determine the fineness of cotton fibers with the help of air flow in the HVI device. The fineness (microner) value, which is a measure for cotton fiber, is found by passing a certain amount of air flow through the fibers in a known chamber and noting the pressure value.( TS 1174 - ISO 2403)
Fiber fineness is a fundamental property and determines where the fiber can be used. Fiber fineness is important in terms of yarn count, unevenness, strength and waste values. Micronaire is a measure of fiber fineness and is the weight per unit length of fiber. Expression of the weight in micrograms of 1 inch long fiber.
Standard atmosphere conditions, HVI (High-Volume Instruments), precision balance (0,2% accuracy), fiber sample.
( HVI device;It works on the principle of air permeability. The device measures the flow rate of the air under constant pressure passed through the fiber ball of constant weight, which is compressed into a 1 inch2 area, and records the pressure differences with a scale system..)
A sample of sufficient weight taken from the bale can be used in all tests. samples; It is cleaned by removing foreign materials such as seeds, sand, stems, etc. Test samples are prepared as 9,5 g – 10,5 g each. The samples are conditioned under standard atmospheric conditions for 4 hours in an environment exposed to air flow or for 12 hours in a still environment.
The thinness test is carried out by fibrofine. Fibrofin; It consists of precision balance and sample chamber. The fineness test is selected from the computer screen. The tested bale number is entered into the computer. The fiber sample is weighed between 9,5 g and 10,5 g on the precision balance of the device. The device automatically saves the measured weight in its memory. The sample fibers are placed in the measuring chamber of the device after being opened a little by hand, and the cover of the chamber is closed. The test starts. 6 bar – 6,5 bar compressed air is passed through the sample and the fiber fineness value (microner) value is measured thanks to the air flow passing through the fiber. The sample is automatically ejected when the process is complete. The above processes are repeated for other samples.
The results that appear on the screen after the test is complete give the fineness of the cotton fiber in micronaire. The fineness values (microner) are output from the device's printer and evaluated. The fineness evaluation according to the micronaire value is made as follows.
Micronaire Value and Evaluation
Micronaire Value (μg/inch) Evaluation
Less than 3,0 Very thin
3 – 3,9 Thin
4 – 4,9 Medium
5 – 5,9 Bold
6 - above too thick