USTER AFIS (Advanced Fiber Information System) Report Analysis

The unique measuring system of the USTER® AFIS counts every fiber, neps and trash particle one by one. The fiber individualizer ensures single fiber measurement, with a gentle opening of the test material. The USTER® AFIS is the standard system for nep measurement, recognized worldwide, and used from cotton ginning to yarn manufacturing. It measures various fiber characteristics such as fiber length, maturity, trash, and nep content.

Measuring Principle

The measuring principle of USTER AFIS is different from that of the USTER TESTER so far as the USTER AFIS is an optical system. (Figure-1)

A fiber sample of 500 mg (making into a 30 cm thin sliver form) is inserted into the fiber individualizer unit that separates the specimen into three main components:

• Lint: Fiber, short fibers, neps, seed coat neps.
• Trash & dust: Trash, dust, fiber fragments, very large seed coat with little or no attached fibers.

Figure 1: Measuring principle of AFIS

Report Analysis:

Figure 2: An example of AFIS report

AFIS Modules:

The USTER AFIS PRO comes with different modules enabling a customized configuration for each plant.

i)                NC Module (Nep Classification)

-        Fiber neps and seed coat neps

-        Count and size distribution

Information obtained from NC Module: 

 

Ranges of Neps and SCNs in raw cotton (Upland)

Effect of neps and SCNs on subsequent textile processing are as follows:

·       A higher number of neps and SCN hampers the premium look/aesthetics of the fabric.

·       A higher number neps and SCN causes uneven dyeing and also responsible for dyeing shade variation.

·       White specs are dye resistant neps on fabric which results undyed spots on fabric surface.

·       Immature fiber neps are highly responsible for shade variation in dyeing as they cannot absorb dye properly because of their under developed cell wall.

·       Biological neps that is mainly generated during ginning results small dark specks in greige fabric.

ii)             L & M Module (Length & Maturity)

-        Length by weight and number

-        Short fiber content

-        Maturity ratio

-        Immature fiber content

Information obtained from L & M Module:

Length information by number(n):

-        L(n): The mean length by number is the average fiber length of all the cotton fibers in the sample.

-        L(n) CV%: The variation of fiber length around the average is expressed as length variation by number or CV%

-        L(n) 5%: The 5% length by number is the length of the lobger 5% of all fibers in a cotton sample.

-        SFC (n): The short fiber content nu number s is the percent of all fibers in a cotton sample that are shorter than 0.5 inches or 12.7 mm.

 

Figure 3: Fiber length distribution (n) versus (w)

Length Information by weight(w):

-        L (w): The mean length of fiber by weight is the average fiber length of all the cotton fibers in the sample.

-        L(w) CV%: The variation of fiber length around the average is expressed as length variation by weight or CV%

-        UQL(w): UQL is equivalent to the Upper Quartile Length at the right end of the upper quartile of the sample diagram. In other words, the upper quartile length by weight is the length of the longer 25% of the all fibers in a cotton sample.

-        SFC(w): The short fiber content by weight is the percent of all fibers in a cotton sample that are shorter than 0.5 inches or 12.7 mm.

Different length groups of fiber:

Ranges of short fiber content (n) and (w) in raw cotton (Upland):

Significance of fiber length and effect of SFC on subsequent textile processing are as follows:

·       In general, a longer average fiber length is preferred because it confers a number of advantages:

1)    Firstly, longer fibers are easier to process.

2)    Secondly, more even yarns can be produced from them because there are less fiber ends in a given length of yarn.

3)    Thirdly, a higher strength of yarn can be produced from them for the same level of twist.

4)    Length is related to fiber characteristics such as strength, fineness, maturity and evenness.

·       Longer fibers are generally stronger, finer and more uniform than shorter fibers.

·     Increased yarn strength results higher productivity in weaving and knitting.

·       A higher value of short fiber (SFC) is responsible for increased hairiness. Increased can create higher chance of pill formation on fabric surface. Furthermore, increased hairiness can create problems in dyeing and printing (reduces design sharpness in printing).

·       A higher value of short fiber (SFC) can cause fly and dust generation in subsequent textile processing.

·    A higher value of short fiber (SFC) can cause GSM variation in subsequent textile processing (knitting, dyeing, finishing, etc.)

·       A higher value of short fiber (SFC) can reduce lustrous property of fabric which may result additional fabric processing (i.e., singeing, sanforizing, etc.)

Maturity and Fineness:

The AFIS measures maturity indirectly by measuring the fiber shape. Each time the fiber passes the optical sensors, two signals are detected two different angles by optical sensors.

Figure 4: Two cotton varieties of different fineness and different stages of maturity

Ranges of maturity, immature fiber content and fineness in raw cotton (short, medium & long staple): 

 Effect of maturity and fiber fineness on subsequent textile processing are as follows:

·  Highly mature fiber provides even dye uptake% and results in minimization of shade variation. On the other hand, a higher amount of immature fiber causes shade variations in dyeing.

· Finer fiber possesses a large number of processing benefits in textile manufacturing.

1)    Finer fiber ensures a greater number of fibers in the cross-section, resulting the basic irregularity is reduced.

2)    A fine fiber can be spun finer than a coarse fiber measurement of fineness. In other words, the finer the fiber, the higher the yarn count will be.

3)    As fine fiber gives more uniform yarn, so it gives good quality fabric with uniform properties and reduces the chance of getting faulty fabric.

4)    Finer fiber ensures higher reflection of light and thus improves the fabric lustrous.

iii)           Trash Module

-        Dust

-        Trash

-        Total foreign matter

ITMF definition of Dust and Trash particles: 

Information obtained from T-Module:

The T-module measures the amount and size of dust and trash particles in cotton fibers. It helps to optimize process settings to minimize the adverse effects of dust and trash particles. But the positive perspective is that most of the dust and trash are eliminated from the yarn manufacturing stage at spinning mills.

Effects of Trash and dust on subsequent textile processing are as follows:

·       Presence of dust and trash may cause visible quality problems in greige fabric.

·       The presence of dust and trash may cause dark and light spots on dyed fabric.

·       The presence of dust and trash may cause faded shade in dyed fabric.

References

1. uTESTER6 The Total Testing Center™. (n.d.). Technical data.
2. Uddin, A. J. (n.d.). Process control of spinning: Part B.
3. Imtiaz, S. (n.d.). Yarn unevenness and its impact on quality.
4. Booth, J. E. (n.d.). Principles of textile testing.
5. Nishi, S. I. (n.d.). Fiber and yarn testing: Part A.