Introduce with High Volume Instrument

Introduce with High Volume Instrument (HVI)

Advanced fiber testing system high volume instrument is used for determine fiber properties in bale management system. It is fiber classing system. HVI is used to determine fiber length, strength, maturity, micronaire and other properties of cotton fiber. HVI test report helps to law down same properties bale before mixing. Mixing is very important process for spinning.

Tests by HVI

•    Micronaire (Mic)
•    UHML (Upper half Mean length)
•    UI (Uniformity index)
•    SFI (Short Fiber Index)
•    Fiber strength in g/tex
•    Elongation
•    Moisture content
•    Color (Reflectance Rd, Yellowness +b)
•    Color grade(USDA upland, Pima or regional customized color chart)
•    Trash (% Area, trash count) & trash Grade (USDA)
•    SCI (Spinning consistency Index)

Micronaire (Mic)

Parameter is describing the cotton fiber fineness. Micronaire Ratings: below 3.0= very fine 3.1-3.9 =fine 4.0-4.9 =average 5.0-5.9 = course over 6.0 =very coarse
Upper Half Mean Length (UHML)
Upper Half Mean Length means length by weight of the longer 50% of fibers.

Uniformity Index (UI)

Uniformity Index= length uniformity of the fibers. Uniformity index= ML. 100/UHML Classification of the length uniformity: very low-> below 76 low->77-79 average-> 80-82 high->83-85 very high ->above 86

Strength

Breaking force of the fiber bundle divided by fiber fineness Assessment of the fiber strength in gram per tex <gf/tex> (without long staple) below 21= very low 22 to 24 = low 25 to 27= average 28 to 30=high over 30= very high

Short fiber index (SFI)

Short fiber index =percentage of fibers shorter than 1/2 inch or 12.7 mm

Spinning consistency index (SCI)

A coefficient is calculated by means of various quality characteristics by a multiple regression analysis. The SCI used is calculated with the original formula provided by USTER. The main benefit of the SCI is a simplified selection of bales for a predetermined blend of fibres as well as the long-term check of the say material blend.

Color

Reflectance (Rd) – reflectance of the fibers, higher Rd values mean a higher color grade. Yellowness (+b)-Yellowness of the fibers (Nickerson/Hunter scale)

Trash

Trash Area (Tr Area)
•    Area of the sample covered with trash particles.
•    Trash Cnt (Tr cnt)
•    Number of trash particles in a sample.

Ambient conditions

The standard temperate atmosphere for textile testing according to ISO 139
•    Temperature: -20+_(plus minus) 2 degree C -68+_ 4 degree F
•    Relative Humidity(RH):65+_4%

Written by

A.M. Amirul Islam (Washim)

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Flow Chart of Bale Management

Bale management is the first step of spinning. 40% yarn quality come from bale management. Good bale management give good result in yarn manufacturing. Good mixing depends on good bale management.

Flow chart of Bale management

Raw cotton => Bale-Moisture % test => Collect sample (Every bale) => Sample testing => Classify bale => Bale law down => Mixing

flow chart of bale management

Flow Chart of Bale Management

*Ideal Moisture percentage for cotton fibre 7.5% to 8.0%.
*There three testing of bale sample. HVI, AFIS and trash content

Some properties to determine of cotton bale:

  • Length
  • Strength
  • Fineness
  • Maturity
  • Uniformity
  • Rd (Reflectance/Brightness/Whiteness) + b (Yellowness)
  • Trash content
    *According to test result same properties of bale should lay down for mixing.

Written by

A.M. Amirul Islam (Washim)

Facebook: Amirul Islam Washim
E-mail: [email protected]

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Basic Operation in Blow Room

Blow Room: There are some methods of opening the mass of fibres into small tufts before further processing. This process of opening & clean is knows as blow room process. Blow room consists of a number of m/c degree 40% to 70% trash is removed in this section.

basic operation in blow room

Blow Room

Objects of Blow Room Process

  1. To open the compressed layer of bale of cotton or any staple fibers with minimum damage to the fibers.
  2. To remove the impurities like sand, seed, bits, neps & short fibers present in the cotton with minimum loss of lint by opening & blending.
  3. To effect a through blending with minimum neps formation.
  4. To convert the mass of cotton fibres into a uniform thick sheet of cotton both longitudinally & transversely &fed as it in the case of chute feed system or wound in the form of a compactly built lap with minimum lap rejection.
  5. Intensive de-dusting of cotton fibres to extract micro-dust in order to improve the working of opened spinning m/c.
  6. Fibre recovery from the waste produced by the various processes the conversion of fibre to yarn in order to reduce the consumption of raw material.

Basic Operation in Blow Room

  1. Opening

    1. Opening is the first operation required carried out to the stage of flocks in the blow room & to the stage individual fibres in the card flock weight can be reduced to about 0.1mg in the room.
  1. Cleaning

    1. The blow room cannot eliminate all or even almost all of the foreign matter in the raw material.
    2. A blow room installation removes approximately 40% to 70% of the impurities.
    3. The result is dependent on raw material on the m/c s & on environment.
  1. Dust removal

    1. Dust removal is not easy operation since the dust particles are completely enclosed in the flocks & hence are back during suction.
    2. The suction units remove dust 64 dust removal will more intensive the smaller the flocks.
  1. Blending

    1. Fibers can be blending at various stages of the process. These possibilities should always be exploited.
    2. The start of the process is one of most important stages for blending.
    3. Intensive blending in a suitable blending m/c must be carried out after separate flock extraction from individual bales of layout.
    4. This blending operation must collect the sequentially arriving bunches of fibers from individual bales & mixes them thoroughly.
  1. Even feed of material of the card

    1. Finally the blow room must ensure that raw material is evenly delivered to the cards. Previously, this was carried out by means of precisely weighed laps from the scutcher, but automatic flock feeding installations are increasingly being used.
    2. While in the introductory phase such installations were subject to problem regarding evenness of flock deliver, today they generally operate well or at least adequately.

Written by

Engineer Sheikh Nurja

B.Sc engineer of textile

Merchandiser at buying house

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Blending in Spinning Mill

Blending may be defined as a condition in which every fibre characteristic is found in the same proportion as in the original blending within every unit cross section of the yarn .Fibre blending has been practiced since the beginning of the cotton textile industry due to the variation in the physical properties of cotton fibres like scrapple length, fineness, strength & cleanliness.

Blending in Spinning Mill

blending in spinning millObjects of blending

  • To achieve uniform quality of product for a longer duration.
  • To improve processing performance, increase yarn strength.
  • To reduce & control cost of production.
  • To facilitate the cotton for regaining its moisture content lost during baling.

Blending procedure

Stages in Blending operation, Blending is carried our three stages:

  • Metering determination & precise establishment of quantities of the individual components.
  • Mixing that is bringing together of the metered quantities.
  • Intermingling distributing the components evenly in the body of fibres.

Types of blending operation

Blending type     

Process stage

Bale Mixing Before the blow room
Flock blending Within the blow room
Lap blending By using scatters
Web blending At the ribbon-lap m/c or the blending
Sliver blending At the D/F,the sliver-lap m/c the comber
Fibre blending At the card or the OE- spinning m/c
Roving blending At the Ring Spinning m/c

Blending Techniques

To achieve homogeneous blend the following techniques were adopted.

  • Lap Blending
  • Card Blending.
  • Bin Blending.
  • Hand-stock Blending.
  • D/F Blending.
  • Massive Blending.

Here detailing about some common technique of blending

Lap blending

The blending technique is still used successfully to permit the blending of cotton of contrasting fiber properties to produce a variety of end users. A doubling scutcher is requires, this has a conveyor lattice in feed on which from four to six laps could be laid. The lap sheets from these laps passed doubled through a beater position followed by pair of cages &lap winding device.

Advantage of Lap blending

Procedure very good transverse blends & also a good longitudinal blend.

  • It is very easy process.

Disadvantages of Lap blending

  • Blend proportions are limited.
  • Need for control of lap wt.

Card Blending

Blending by doubling with laps at the card is sometimes used in high production cards. The procedure involves use of a double lap roll attachment whose feed rolls are positively driven by a link chain by the regular lap roll gear.

Advantages of Card Blending

  • Most intimate blend is obtained.
  • This method is used to randomly mix two laps differing in color.

Disadvantages of Card Blending

  • It can’t be obtained from wide range.
  • Controlled metered blending can’t be carried out.
  • Only make a previously proceeded blend more intimate.

D/F Blending

With D/F blending the card slivers are doubled at the drawing process in a predetermined fashion. The percentage of the blending depends on the number of slivers processed. In processing of cotton this method is not used for blending purposes, but it is the most popular method for blending man-made fiber fiber with cotton.

Advantage of D/F Blending

  • Suitable for blending two different cotton qualities.
  • Provide best blend in the longitudinal direction.
  • Working procedure is not complex.

Disadvantage of D/F Blending

  • Require additional blending passage.
  • Stripiness may be produce in the finished product.
  • Poor transverse blending in the product.
  • Fiber heterogeneity produced.

Written by

Engineer Sheikh Nurja

B.Sc engineer of textile

Merchandiser at buying house

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Mixing in the Spinning Mill

Mixing is the first and important process in the spinning process. Mixing is a process by which different grade of same fiber are kept together.

Types of Mixing

  • Volume mixing.
  • Bin mixing.
  • Card mixing.
  • Weight mixing.
  • Automatic mixing.
  • Hand stock mixing.
  • Lap mixing.
  • Sliver mixing.
  • Mixing by hopper.

Mixing in the Spinning Mill

mixing in the spinning mill

Mixing in a Spinning Mill

Factors to be Considered Before Doing Mixing

Length of cotton

The length of the fibers should be equal otherwise various types of problem will create. Fibers having different length causes problem in drafting zone &also in simplex or ring frame.

Micronaire of cotton

The second considerable factor for mixing is the micronaire value of fiber, the higher, the micronaire value, the fibers are regarded coarser.

Color of cotton

Color is also a very important factor in mixing. In case of cotton, it is measured by brightness of cotton and the presence of yellow color in cotton.

Micronaire CV % of mixing bales

The micronaire CV % of mixing bales should be 5%.

Micronaire deviation

The micronaire deviation of cotton fibers should be (+-0.1) or (+-0.05). Otherwise mixing quality cannot be classified as good quality.

Length deviation

Length deviation should not exceed 10% deviation from mixing to mixing for the same lot.

Color deviation

in mixing, two lot of adjacent color can be mixed, such as white and light spotted or light spotted and can be mixed. But white and spotted cannot be mixed.

Lay down

Every cross section of the lay down plant should be same. Which means average micronaire value should be controlled in every cross section.

Written by

Engineer Sheikh Nurja

B.Sc engineer of textile

Merchandiser at buying house

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Ginning Process of Cotton

Ginning

The process by which the fibers are separated from the seeds is called ginning. It is one the most important step of spinning process. After collecting from field, Seed cotton moves to nearby gins for separation of lint and seed. The production of a typical gin is about 12 bale per hour. (here 1 bale = 500 pound)

 Objects of ginning

  1. To make the fiber free from seeds without gin-cut fiber
  2. To get fair price of the cotton
  3. To be confident that fiber does not contains excess and unexpected seeds
  4. To make the spinning process easier and effective
ginning process of cotton

Ginning of cotton

Ginning process of cotton

  • At first the cotton is made to go through dryers to reduce moisture content.
  • Then cotton is made to go through cleaning equipment to remove foreign matters.
  • The cotton is then air conveyed to gin stands where revolving circular saws pull the lint from the saw teeth by air blasts or by rotating brushes.
  • The cotton is compressed into 500 pounds weigh contained bales.
  • Then the bales of cotton are shipped to textile mill for further processes.

Type of ginning

Saw ginning

Advantage of saw ginning

  • Saw ginned cotton is more uniform
  • Cotton is more clean

Disadvantage of saw ginning

  • Possibility of fiber breakage due to drawn up the fiber from the surface of seed
  • Increase neps
  • Increase short fiber content

Roller ginning

Advantage Roller ginning

  • Fiber quality is better than saw ginned cotton
  • High production

Disadvantage Roller ginning

  • The moisture of seed mix up with fiber in processing which cause cake cotton fault.

Faults in ginning

  • Gin-cut fiber
  • Crushed seeds
  • Neps formation
  • Too much wastage

Written by

Engineer Sheikh Nurja

B.Sc engineer of textile

Merchandiser at buying house

If you like this article please do not forget to share on facebook and put your valuable comment