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YARN QUALITY PARAMETERS OF IMPROVED 5.pdf · PDF fileYARN QUALITY PARAMETERS OF IMPROVED CHARKHA ... Charkha however the SITRA norms are better probably because better collons are

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  • CHAPTER V

    YARN QUALITY PARAMETERS OF IMPROVEDCHARKHA

    Yarn Quality plays an important part in determining the working

    of the loom, appearance of the cloth woven and ultimately the price of

    cloth. Better the yarn quality more is the yarn demand for the yarn

    and higher will be the market price for good quality yarns. SITRA has

    evolved quality standards or Norms for the cotton yarns spun. The

    yarns that are produced on the different charkhas have been

    ultimately compared for quality against SITRA Norms to see we ,ther

    they meet the quality requirements. The quality particulars have been

    evaluated for each count that is spun on the charkha

    5.1 Yarn Quality Parameters To Be Tested andEvaluated

    Yarn samples were spun on all the 3 types of spinning

    machines namely 8 Spindle Hand Operated Charkha, 8 Spindle

    Motor Operated Charkha and 16 Spindle Improved Charkha. The

    roving bobbin of 0.90 hank was taken to Spin 10s' and 33s Nm and

    1.20 hank roving was used to spin 64s and 72s Nm. The Spindle

    speeds were kept at 5500 rpm and 6500 rpm. Only when the speed

    exceed 6500 rpm and above the yarn quality deteriorated due to

    excessive end breakages and it was not practical to run the

    machine at speeds exceeding 6500 rpm as the stoppage time of the

    machine to repair broken threads has become very high. A total of

    139

  • \

    20 readings for each count was taken to get the average yarn

    quality characteristics like CV% of TPI, U%, Thin place/km, Thick

    place/km, Neps/km, Rkm values, % of Elongation and Hairiness

    Index. The quality particulars of the yarn have been tested and the

    results have been analyzed. It can be seen from the test results that

    there is vast improvement in yarn quality, obtained with yarn

    produced on improved charkha and the quality levels are

    comparable with SITRA* norms for mill made yarn of similar counts.

    There is also appreciable improvement in yarn quality when shifts

    are made from Hand-Operated Charkha to Motorized charkha and

    16 Spindle Improved Charkha for all counts. This is because of the

    uniform twist flow to the yarn during charkha spinning as the

    spindles are driven by motor; this ensures constant speed of

    rotation of the machine parts. This stabilization of TPI has yielded

    better yarn quality.

    5.2.0 Yarn Quality Characteristics

    5.2.1 Yarn Quality Characteristics Of 10s Nm spun on charkhas

    (5500 rpm and 6500 rpm)

    10s Nm** count was spun on the selected charkhas with 5500

    rpm and 6500 rpm of spindle speeds .The quality particulars of 10s

    Nm count are obtained from 8 Spindle Hand Operated Charkha, 8

    Spindle Motor Operated Charkha and 16 Spindle Improved Charkha

    are compared with SITRA norms.

    * SITRA - South India Textile Research Association, Coimbatore

    140

  • The TPI (Twist Per Inch) 10.0 is given to the yarn, which is kept

    constant for all the charkhas.

    The trial was taken on 8 Spindle Hand Operated Charkha, 8

    Spindle Motor Operated Charkha, 16 Spindle Improved Charkha on

    10s Nm at a constant speed of 5500 rpm and 6500 rpm. The yarn

    was tested for various parameters like CV% of TPI, U%, Thin

    places/km, Thick places/km, Neps/km, Rkm values, Percentage of

    Elongation and Hairiness Index. Average of 20 readings for each

    quality particulars is given in the Table- 5.1 and 5.2.

    5.2.2 CV% of TPI

    CV % of TPI affect the working of the yarn in looms. Lower

    CV% of TPI is preferable. From the Table -5.1 it is evident that the

    CV% of TPI are higher in the yarns made out of 8 Spindle Hand

    Operated Charkha, this is because of irregular rotation of handle of

    the machine. But the 8 Spindle Motorised Charkha shows 22.4

    percentage improvement when compared to 8 Spindle Hand

    Operated Charkha. Similarly the CV% of TPI shows 64.2 percentage

    improvement in 16 Spindle Improved Charkha when compared with

    Hand Operated Charkha and 53.9 percentage improvement when

    compared with 8 Spindle Motor Operated Charkha. Even when the

    speeds of the charkha were increased to 6500 rpm in Table - 5.2, it

    is observed that there is a 30 percentage improvement in CV% of TPI

    in the 16 Spindle Improved Charkha.

    ** Nm - Metric System Of Yarn Numbering

    141

  • 5.2.3 U%

    U % means uniformity index of the yarn tested is lister

    evenness tester (Evenness of yarn). The lower U% means better

    quality. The U% rating of 8 Spindle Hand Operated Charkha yam

    shows higher values than other two charka yarns. The.re is a 15.3

    percentage improvement of U% in the 16 Spindle Improved Charkha

    when compared with 8 Spindle Hand Operated Charkha in Table-

    5.1. However the SITRA norms give lower values. Among the three

    charkhas, 16 spindle motor operated charkha yielded better yarn with

    16.56 U% for 10s Nm at 5500 rpm.

    5.2.4 THIN PLACES/Km

    Table - 5.1 indicates the performance of 10s Nm yarn in terms

    of thin places (Yarn imperfections). There is a 82.2 percentage

    improvement in the yarn imperfections for 10s Nm count at 5500 rpm

    of spindle speeds, between hand operated 8 spindle yarn and 16

    Spindle Charkha. The 16 Spindle Charkha has given better quality

    than SITRA norms. The 8 Spindle Hand Operated Charkha shows

    higher values because of the irregular motion of charkha and jerky

    rotation of fluted rollers. But, the 16 Spindle Improved Charkha shows

    4 percentage improvement when compared with 8 Spindle Motor

    Operated Charkha and 82.2 percentage improvement when

    compared with Hand Operated Charkha, because of smooth rotation

    of drafting rollers and no vibration in improved machine. This has

    confirmed that 16 spindle improved charkha has yielded better results

    among the charkhas selected for the study. Even at higher speeds of

    144

  • 6500 rpm in Table - 5.2, there continues to be reduction of thin

    places in yarn spun on improved charkha.

    5.2.5 THICK PLACES/Km

    Table - 5.1 indicates the performance of thick places at 5500

    rpm {Yarn imperfections). There is a 48.6 percentage improvement in

    the yarn imperfections for 10s Nm count between 8 spindle hand

    operated and 8 spindle motor operated. The 16 Spindle Charkha has

    given better quality than SITRA norms and the 16 spindle charkha

    has yielded better yarn showing an improvement of 53 percentage

    over hand operated charkha yarn and 3.5 percentage improvement

    over 8 spindle motor operated charkha yarns. Even at 6500 rpm the

    thick places have come down in 16 Spindle Improved Charkha in

    Table - 5.2. This was because of smooth rotation of drafting rollers

    and no vibration in 16 spindle-improved charkhas.

    5.2.6 IMEPS/Km

    Neps are defined as entanglement of immature fibers into small

    ball the size of a pinhead. The neps undesirable both in the yarn and

    the fabric as theyappear as fabric defect. These neps do not qbserii'

    the dye applied on to the fabric uniformly, because they consist of

    immature fibers. Therefore steps are taken to reduce the nep

    generation in the spinning process. It is the blow room and the

    carding departments that contribute to nep generation. The neps of

    16 Spindle improved Charkha shows 3.48 percentage improvement

    in yarn imperfections when compared with 8 Spindle Hand Operated

    145

  • Charkha however the SITRA norms are better probably because

    better collons are used in the mills and latest spinning machinery are

    available in the mills. Neps generation has been attributed to mainly

    the beater speeds, settings in blow room and carding settings

    between feed plate and taker in.

    5.2.7 TOTAL IMPERFECTIONS/Km

    The total imperfections are the sum of thin place, thick place

    and neps/Km of yarn. It goes to show the total yarn defects in a

    Kilometer of yarn length. Total imperfections influences loom

    performance and over all fabric appearance. Less number of

    imperfections in yarn is preferred for better yarn quality. The Table-

    5.1 indicates that the total imperfections of 10s Nm count shows 57.1

    percentage improvement when compared between 8 spindle hand

    operated and 16 spindle improved charkhas and 3.6 percentage

    improvement in the 16 Spindle Improved Charkha when compared

    with 8 Spindle Motor Operated Charkhas. At speeds of 6500 rpm in

    Table - 5.2, it is noticed that the total imperfections in 16 Spindle

    Charkha is comparable to SITRA quality standards.

    5.2.8 RKM VALUES

    Stronger the yarn, higher will be the RKM value. Stronger yarns

    produce stronger cloth and spin better without end breakage. The

    RKM value of 16 Spindle Improved Charkha shows 31.8 percentage

    and 4.8 percentage improvement when compared with 8 Spindle

    Hand Operated Charkha and 8 Spindle Motor operated Charkha

    146

  • respectively at 5500 rpm of spindle speed for 10s Nm. From this

    table, the 16 Spindle Improved Charkha values are higher than 8

    Spindle Motor Operated Charkha, because of uniform motor speed

    and also less vibration of machine. Here the RKM values of different

    Charkhas are equal to SITRA norm values. So the higher RKM

    means stronger yarns. Hence, it can be inferred that 16 Spindle

    Improved Charkha is giving better yarn strength than ring spun yarns.

    It can be obs

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