HVI calibration principles

HVI uses a unique calibration principle by which routine calibration is performed by presenting samples bf known value to the instrument, which then makes adjustment to the raw instrument values, obtained so that measurements will agree with the calibration cotton designated values. The general principle by which this calibration is done involves a simple, two-point regression analysis.

In actual practice, raw values from the instrument will not match exactly with the designated values due to the variety of reasons including component ageing, atmospheric conditions and other sources of calibration drift. In such cases, the computer software makes adjustments to the raw data by using regression analysis. For the calibration of length, strength and micronaire, ICC cotton can be used while the calibration of colour has to be performed using the standard colour tiles supplied along with the instrument.

Advanced Fibre Information System (AFIS)

Advanced Fibre Information System is based on the single fibre testing. There are two modules here, one for testing the number of neps and the size of neps, while the other one is used for testing the length and the diameter. Both modules can be applied separately or together.

With the introduction of AFIS, it is possible to determine the average properties for a sample, and also the variation from the fibre to fibre. The information content in the AFIS is more. The spinning mill is dependant on the AFIS testing method, to achieve the optimum conditions with the available raw material and processing machinery. The AFIS-N module is dealt here and it is basically used for counting the number of neps and the size of neps. The testing time per sample is 3 minutes in AFIS-.N module.

This system is quick, purpose oriented and reproducible counting of neps in raw material and at all process stages of short staple spinning mill. It is thus possible, based on forecasts supervisory measures and early warning information to practically eliminate subsequent complaints with respect to finished product. The lab personnel is freed from the time consuming, delicate and unpopular, proceeding of nep counting. Personnel turnover and job rotation no more affects the results of the nep counting. The personnel responsible for quality can now at least deal with the unpopular neps in a more purpose-oriented manner than ever before.

AFIS -Working principle

Advanced Fibre Information System (AFIS)

Source: International Textile Centre

A fibre sample of approximately 500 mg is inserted between the feed roller and the feed plate of the AFIS-N instrument Opening rollers open the fibre assembly and separate off the fibres, neps, trash and dust. The trash particles and dust are suctioned off to extraction. On their way through the transportation and acceleration channels, the fibres and neps pass through the optical sensor, which determines the number and size of the neps.

The corresponding impulses are converted into electrical signals, which are then transmitted to a microcomputer for evaluation purposes. According to these analyses, a distinction is made between the single fibres and the neps. The statistical data are calculated and printed out through a printer. The measuring process can be controlled through a PC-keyboard and a screen.

Time requirement

It can be evidenced that the resu Its are provided very quickly using the AFIS measurement method and this with reference to approximately the same weight of sample material. This to be particularly the case when one compares the AFIS-N method with the frequently- used manual/ visual ASTM method. The savings are 150 with raw cotton and 1:25 with draw frame sliver.