Fibre MeasurementsHVI & AFIS

Prof.Dr.S.KathirrveluEITEX-BDU

1PCTM

PCTM 2

PCTM 3

PCTM 4

5PCTM

• AFIS is a modular device intended for testing and

analysing of 100% cotton samples in the form of

bale, opened and cleaned material (card mat),

sliver and roving.

• This device belongs to high-efficiency testing

lines frequently called HVI (high volume

instrument).

6PCTM

The history of such devices started in 90´s -

Zellweger Uster launched the first devices

specialized to neps analysing.

Thanks to further development at present

AFIS offers also other modules, from which L

(length) and T (trash) modules are most

widely used.

The main advantage of AFIS device is testing without

application of any clamps - fiber strand (ca 0,5 kg, 30 cm)

is delivered to opening mechanism, where the strand is

open up to individual fibres, which are measured by

different sensors.

Standard testing procedure contains five partial tests,

test result represents mean value and (and variation) of

measured parameter.

N&L&T modules and can measure neps, length

parameters and trash and parameters. 7PCTM

8PCTM

N Module

- nep count per gram – fibre neps + seed coat neps

- nep size [micron] – fibre neps + seed coat neps

- SCN /g – seed coat nep count per gram

-SCN size – seed coat nep sizeT Module

- Total Cnt/g – trash count per 1g

- Cnt/g – trash count per gram (particle size > 500m)

- Dust Cnt/g – dust count per gram (particle size < 500m)

- Mean Size &- VFM % - visible foreign matter (dust and trash

content in %) suitable parameter for sample comparison

• ADVANCED FIBER INFORMATION SYSTEM (AFIS)• Introduction:

• In textile industry raw material is the most dominant factor as it

contributes 50-75% in total manufacturing cost.

• In quality conscious scenario, quality of raw material plays a vital role.

But the quality of raw material is decided by measuring its properties.

• Now measurement through conventional techniques is very laborious

and time consuming.

• Hence the researchers focus their attention towards the inventions of

such instrument, which gives accurate and quick result and one of the

wonderful development is AFIS - Advanced fibre information system.

PCTM 9

• BASIC PRINCIPLE of AFIS:

• The AFIS method is based on aeromechanical

fibre processing, similar to opening and carding,

followed by electro-optical sensing and then by

high speed microprocessor based computing

and data reporting as shown in Figure.

PCTM 10

• A fibre sample is introduced into the system and isprocessed through a fibre individualizer, which aeromechanically separates the sample into threecomponents consisting of cleaned fibre, micro dust,and trash.

• Each of these components is transported in aseparate pneumatic path and may be analysedelectro-optically or by other means.

• The data processing and reporting are handled byan industrialized PC.

PCTM 11

PCTM 12

• AFIS provides basic single fibre information and

is distinguished from earlier and existing

methods by providing distributions of the basic

fibre properties. These distribution

measurements provide more accurate, precise,

and basic information about fibre.

PCTM 13

• Fibre individualizer:

• The fibre individualizer (in Figure) uses

unique cleaning and separating techniques to

present the fibres pneumatically to the

electro-optical sensor.

PCTM 14

PCTM 15

1. The fibres are opened and cleaned using specially designed, pinned and perforated cylinders,

which are similar to open end spinning beaters and stationary carding flats.

2. Airflow into the perforations of the cylinder allows for thorough engagement and efficient

dust and trash removal.

3. A specimen of fibre is hand teased into a sliver-like strand and is inserted into the feed

assembly.

4. It passes between a spring-loaded feed roll/feed plate assembly and is engaged by the pinned

and perforated cylinder.

5. The fibres are combed and carded; dust is released and removed through the perforations in

the cylinder.

6. Trash is released after the carding action by the "counter flow" separation slot.

7. Heavy trash particles are separated from fibres and transported out of the system, whereas,

the smaller dust and fibres are returned to the cylinder aerodynamically by the air drawn into

the slot, thus the term "counter flow slot".

PCTM 16

• A secondary stationary flat is used to furtherclean and comb the fibres. They are then directlytransferred to a second cylinder.

• A second "counter flow" slot removes additionaltrash. Its counter flow air is used to transportfibres out of the system after a final combingfrom a third stationary carding flat.

• The separated components (cleaned fibre, microdust and trash) are transported along threedifferent production paths.

PCTM 17

• Fibre individualizer motor/Motor controller:

• Versions 3 and 4 units have a separate drive motor for

fibre individualizer.

• These brushless DC motors are noiseless in operation,

allow for direct monitoring and control of the motor

speed, and are easier to service and replace.

• The brushless DC motor has its own motor controller

board which monitors and controls and motor speed.

• The motor speed can be adjusted by a potentiometer

located on the board.PCTM 18

• Feed motor/Motor controller:

• Versions 3 and 4 units feed belts and feed rollers are driven

via worm gear with a stepper motor.

• The motor speed is variable from 140 steps/sec to 1116

steps/sec.

• The feed motor controller is a motor driver that accepts

pulses and direction information from the control board.

• The initial direction of the stepper is determined by the

orientation of the motor's 7-pin plug on the controller.

• If the direction is "backward" after installation, reverse the

plug.PCTM 19

• Sliver detector: The sliver detector is located between the feed tray and feed

plate.

• Its function is to signal the control system when sliver is being presented to the

individualizer and when sliver is no longer present.

• The sliver detector consists of an infrared LED source and detector.

• During operation, the sliver (fibre specimen) passes between the source and

detector 'breaking" the beam which signals the control board to slow the feed rate

to the sampling speed.

• When the trailing end of the sliver passes through the source/detector the beam

is "made" once again.

• A 15second delay is triggered to allow the remaining sliver to continue processing

through the system before the "end of sample" sequence is initiated by the control

board.

PCTM 20

• Electro-optical sensors:

• The electro-optical (E-O) sensors consist of

three basic elements tapered entrance and

exit nozzles (on Version 4 lint sensor, a single

piece accelerating nozzle) beam forming and

collection optics.

• The detection circuitry (in Figure).

PCTM 21

PCTM 22

• Individualized fibres (and neps) are transportedpneumatically from the fibre individualizer by an airstream.

• They enter the E.O. sensor through an acceleratingnozzle which straightens, separates, and aligns thefibres in proper orientation to the source detector.

• The fibres penetrate a collimated beam of light andscatter and block that light in proportion to theiroptical diameter and in direct relation to their timeof flight through the sampling volume.

PCTM 23

• Generally, rectangular waveforms are produced by the

light scattered by individual fibres. Nep signals are much

greater in magnitude and duration and generate a

characteristic nep "spike". Trash particles produce smaller

spiked waveforms, which are distinguishable from neps in

magnitude and duration.

• From these waveforms, which are microseconds in

duration, the pertinent data are acquired, analyzed and

stored in the host computer. Distributions based on size,

length or diameter can be generated.

PCTM 24

• DATA ANALYSIS:

• I) Lengths by number (n):

• Fibre length by number is the length of the

individual fibres. This method measures the

length of each fibre and places them into length

categories.

• These categories are added together to obtain

the length measurement for short fibre and

average or mean length.PCTM 25

PCTM 26

• Length by number measurements is pure measurements

that are not influenced by the weight of the fibres.

Typically this means that the length by number results are

always shorter than the same sample tested using the by

weight method.

• In textile processing, it is recommended that the length by

number be used to determine machine and equipment

settings and also to determine fibre damage as

represented by short fibre content.

• Instrument such as the AFIS is capable of providing the

length by number information.PCTM 27

PCTM 28

• The Advanced Fibre Information System (AFIS) was

developed to measure traditional fibre neps

(entanglements) often times called mechanical neps.

• A recent breakthrough development has furthered the

technology for classifying neps into two categories fibre

neps and seed coat neps. AFIS nep classification is the

newest addition to the modular AFIS system providing a

more detailed summary of nep type imperfections from

ginned cotton through carded and combed sliver.

PCTM 29

• III) Seed coat nep detection method:

1. The lint channel contains fibres, short fibres, mechanical neps and seed

coats with fibres attached.

2. The trash channel contains trash, dust, some fibre fragments and very

large seed coats with little or no attached fibre.

3. The seed coats, which remain with the fibre during opening are termed

seed coat neps by the AFIS.

4. These are masses that are most likely to remain with the good fibre

during the textile opening, cleaning, carding, and combing processes.

5. Large seed coats, termed seed coat fragments, are collected in the

trash port of the AFIS and are more easily removed from the fibre.

PCTM 30

PCTM 31

• The AFIS nep classification module counts and sizes seed coat neps. The classification

module is able to identify the distinct electrical waveforms produced by fibres, fibre

clumps, seed coat neps, etc.

• This improved nep module uses a digital signal processor (DSP) to classify all incoming

waveforms and to calculate nep size. Figure illustrates a typical nep waveform and the

values extracted by the standard nep module. Figure illustrates the same signal analyzed

by the DSP system.

• The DSP system is capable of recording and analyzing all information contained in the

nep signal, therefore providing better information about the sample characteristics. The

classification software compares each sampled waveform to a standard waveform to

determine which classification it most resembles.

• These standard waveforms are based on models of seed coat neps and mechanical neps

travelling through the sensor and are verified on numerous simulations using manually

introduced fibre neps and seed coat neps.

PCTM 32

AFIS APPLICATIONS:

(1) Card nep analysis: Neps are created by mechanical handling and cleaning of cotton

fibres. Due to fibre individualizer provided inside the machine we can analyze neps

hence we can check nep in carded or combed sliver.

(2) Card wire maintenance analysis: We can judge the grinding frequency required for

card wires by appropriate checking of sliver quality on AFIS instrument.

(3) Length applications : This instrument will provide various fiber length data so that it

will be helpful to control the imperfection in the final yarn.

(4) Length analysis of comber and D/F: This instrument provides the data on histogram

i.e. in form of fibre distribution so it will give accurate idea about length.

(5) Trash application:: By using this instrument we come to know the exact amount of

trash present in material so that we can decide the material is suitable for processing or

not.

PCTM 33

• ADVANTAGES:

1. High degree of accuracy, which gives precise

results.

2. Testing speed is high.

3. It avoids laborious time work needed for

measurement of nep count.

4. The results are free from human and machine

error.

5. It can analyze process performance.PCTM 34

PCTM 35

PCTM 36

HIGH VOLUME INSTRUMENT TESTING (HVI)

THE BASICS:

The Uster HVI 900 system measures the seven physical

characteristics defined by the United States Department of

Agriculture (USDA) in its cotton marketing system.

The Uster HVI 900 system measures :

1. Fibre length 2. Fibre strength 3. Length uniformity 4.

Elongation 5. Micronaire 6. Color 7. Trash

PCTM 37

PCTM 38

• BACKGROUND:

• The testing of fibers was always of importance to the

spinner.

• It has been known for a long time that the fiber

characteristics have a decisive impact on the running

behavior of the production machines, as well as on the

yarn quality and manufacturing costs.

• In spite of the fact that fiber characteristics are very

important for yarn production, the sample size for

testing fiber characteristics is not big enough.

PCTM 39

• This is due to the following:

• The labour and time involvement for the testing of a

representative sample was too expensive. The results were

often available much too late to take corrective action.

• The results often depended on the operator and/or the

instrument, and could therefore not be considered objective

• One failed in trying to rationally administer the flood of the

raw material data, to evaluate such data and to introduce the

necessary corrective measures.

PCTM 40

• Only recently technical achievements have madepossible the development of automatic computer-controlled testing equipment. With their use, it ispossible to quickly determine the more important fibercharacteristics.

• Recent developments in HVI technology are the result ofrequests made by textile manufacturers for additionaland more precise fiber property information. Worldwidecompetitive pressure on product price and productquality dictates close control of all resources used in themanufacturing process.

PCTM 41

• Objective of Testing

• Reasons for Textile Testing:

• Checking the quality and suitability of raw material and selection of material.

• Monitoring of production i.e. process control.

• Assessment of final product, whether the quality is acceptable or not, (how

will be the yarn performance in weaving? etc).

• Investigation of faulty materials (analysis of customer complaint,

identification of fault in machine etc.).

• Product development and research.

• Specification testing: Specifications are formed and the materials are tested

to prove whether they fall within the limits allowed in the specification (e.g.

specified by a customer).

PCTM 42

• HVI testing principle

1. Micronaire: Micronaire Reading Measured by relating airflow resistance to the

specific surface of fibers.

2. Maturity: Maturity Ratio Calculated using a sophisticated algorithm based on

several HVI™ measurements.

3. Length: Upper Half Mean Length, Uniformity Index, Short Fiber Index Measured

optically in a tapered fiber

4. beard which is automatically prepared, carded, and brushed.

5. Strength: Strength, Elongation Strength is measured physically by clamping a

fiber bundle between 2 pairs of clamps at known distance. The second pair of

clamps pulls away from the first pair at a constant speed until the fiber bundle

breaks. The distance it travels, extending the fiber bundle before breakage, is

reported as elongation.

PCTM 43

6. Moisture: Moisture Content Moisture content of the cotton sample at

the time of testing, using conductive moisture probe.

7. Color: Rd (Whiteness), +b (Yellowness), Color Grade Measured

optically by different color filters, converted to USDA Upland or Pima

Color Grades or regional customized color chart.

8. Trash: Particle Count, % Surface Area Covered by Trash, Trash Code

Measured optically by utiliz

9. ing a digital camera, and converted to USDA trash grades or

customized regional trash standards.

PCTM 44