Fibre Contamination System (FCT)

The FCT system is used for testing stickiness, neps, trash and seed coat fragments. The sample in the form of bundle is fed into a self-cleaning, micro carding device integrated in the FCT, to produce about 10m of transparent web in order to expose the impurities and contaminants in the best way possible. An area of 1 sq m per sample is tested.

Firstly, the web is analysed by a machine vision system for the presence of trash, neps and seed coat fragments and then they are pressed between the 2 stickiness crush rollers in the same manner as with the crush rolls of the commercial cards. The cotton web removed by the vacuum is then deposited on the stickiness crush rollers. They are examined by a laser signal analysis system for determining the stickiness content. Time taken for one sample is 40 seconds.

The advantages are:

1)    Major contaminants like stickiness, seed coat neps and fibre neps are also considered as parameters for trading cotton.

2)    Evaluation of performance of the precleaning systems such as cards, comber etc, for determination of their optimum operational setting and efficiency are done.

Integrated indices of fibre quality

If a versatile measure of cotton quality can be quantified and universally accepted, it would be enormously valuable in both technical and commercial applications. Numbers of different cottons, such as bales in a warehouse, are much easier to compare if each has one descriptive number rather than several. A single-figure index should meet the following criteria:

• It is based on common HVI results, and should not require purchase of additional instruments.
• It reflects a balance between market forces and technical considerations.
• Is, as often happens, more or fewer properties than usual are tested, the estimate is unbiased, ie for average cottons the premium or discount (p/d) is unchanged.

Different methods of maturity measurement

• The notion that micronaire is a measure of fineness still appears frequently. Double compression airflow measurement.
• Polarised light analysis
• Causticaire, ie, micronaire of conditioned specimens before and after soaking in concentrated caustic soda solution
• Centrifugal methods
• Near infrared spectrometry
• Image analysis

Image analysis

Image analysis of both longitudinal images and sections was applied successfully to the measurement of maturity; Less exactly when the minimum projected width was used. In general image analysis can measure the mean and distribution of several fibre transverse dimensions:

• The apparent fibre diameter, a nebulous concept in a fibre having such a non circular shape, but a useful measure of micronaire, ribbon width is a better term in most image analysers.

The other properties are more apparent when cross sections are made:

• Martin radius, the mean of 8 equidistant radii from the centre of gravity
• Total cross sectional area, including both fibre wall and the hollow lumen
• Cross sectional area of fibre wall an exact measure of linear density and considered along with the above area, a measure of maturity
• Perimetre, nearly a constant for a given variety regardless of the degree of thickening and perhaps the best available measure of standard linear density