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COMBED YARN FOR KNITTING - 3

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DRAWFRAME:

  • Drawframe with a short term  Autoleveller is a must
  • no of doubling should not be less  than 7 and the total draft also should be more  than 7
  • U% should be around 1.5 to 1.8
  • 1 meter C.V% (from Uster Evenness Testing machine ) should be less than 0.6
  • top roller lappings should be almost nil
  • If group creeling is used, all the sliver piecings from the creel should not  enter the tongue and groove roller at the same time
  • no sliver should be removed from the machine after the tongue and groove roller (which is meant for sensing the feed variation) for any reason. Because, draft correction will be done according to tongue and groove roller sensing and there is a time lag between sensing and correction. 
  • top rollers should be checked by the  operators atleast once in a shift
  • top rollers should be checked by the operators , whenever there is a lapping
  • top roller buffing should be done once in 20 days(maximum 30 days)
  • If the top roller eccentricity is more than 0.05 mm, it should be buffed
  • top roller eccentricity should be zero after buffing. 
  • diameter variation between top rollers should be less than 0.1mm
  • sliver test should be conducted atleast once in 15 days and the A% should be less than 0.8
  • the delivery speed should be around 400 to 500 meters per minute depending upon the make of the machine
  • whenever there is a top roller lapping,  min 10meters of sliver should be removed from the can
  • creel breaks should be as low as possible and it need to be piececd properly. Trials should be taken to see the yarn made out of piecing. Piecings  should not be too thick and high twisted

SPEED FRAME:

  • Total draft should be around 10 for 4 over 4 drafting system
  • better to use floating condenser in the front zone to reduce hairiness  and the  diameter of the roving
  • cots buffing should be done once in two months. top roller runout to be checked and it should be nil. There should not be any compromise on top roller quality. Top roller cost for speed frame is negligible if it is compared with ringframe
  • If possible it should be treated with surface treatment  like treatment with LIQIMIX or treated with acid to reduce top clearer waste which is caused by top roller surface 
  • Twist Multplier should be high enough to  reduce stretch in Ringframe.  Higher the T.M lower the classimat "H1" faults
  • If single speed for flyer is used, it is advisable to run less than 1000 rpm
  • When the speed frame bobbin  is full, flyer speed should be less than 1000 rpm. Otherwise surface cuts will increase and thin places also will increase
  • False twisters should be changed  once in two years.  Variation in false twister  will result in high count C.V%
  • Roving tension should be as low as possible and as uniform as possible. Higher the  roving tension, higher the  count C.V% and higher the thin places
  • Density of all roving bobbins should be same. Higher the variation, higher the count C.V%
  • Break draft should be around 1.18 to 1.24 depending upon the type of drafting system and total draft
  • Roving hank should be decided in such a way that the ring frame draft is around 20 to 34 for different counts.
  • no sliver piecing or roving piecing from speedframe should  be worked in Ringframe. All sliver piecing  and roving piecing will result in thin and thick yarn. Some times it may be cut by the clearer, but all yarn faults created by  piecings are not cut  by the clearers.

 

RINGFRAME:

  • Front zone setting should be as close as possible
  • breakdraft of 1.14 and back zone setting of 60 mm is recommended
  • 65 degree shore hardness for front top roller
  • buffing should be carried  out once in 45 days
  • if the top roller diameter is less by 1.5 mm from the standard  diamter,  top roller should be changed
  • the gap between front top roller and apron nip should be as low as possible(around 0.5 to 1 mm). If it is more imperfections will be high
  • bottom and top aprons should be changed atleast once in 1.5 years
  • It is better to use lighter travellers instead of using heavier travellers.  Enough trials should be taken , because traveller size depends upon, speed, micronaire, humidity condition, count, ringdiameter etc
  • It is advisable to use Eliptical travellers for hosiery counts
  • ring travellers should be changed  before  1.5% of travellers burn out
  • whenever there is a multiple break, ring travellers  should be changed
  • At any point of time, fluff accumulation on travellers  should be less. Ring traveller setting should be close enough to remove the waste accumulation but at the same time  it should not disturb the travller running
  • hariness varition between spindles should  not be high. To achieve this, traveller should be changed in time, bad workings (multiple breaks) should be avoided,  rings like TITAN rings (from Breaker) should be used, damaged rings should be removed
  • Ring frame breaks should be as low as possible ( less than 10 breaks per 1000 spindle hours)
  • Start up breaks after doffing should be less than 3 %.
  • Overhead cleaners is a must for processing combed cotton
  • Exhaust trenches should be between machines and for every 200 spindles there should be a trench
  • ring centering should be perfect. Abc rings and lappet hook centering should also be done perfectly
  • If ring diameter is more than 40 mm, ring centering plays a major role.  If ring centering is not done properly, hairiness variation within the chase will be very high
  • good quality spindle tapes should be used and changed for every 24 months. Spindle  speed variaiton will affect yarn strength, tpi and hairiness

WINDING:

  • Winding speed should be around 1250 meters/ min
  • machines with tension management  is preferred
  • Clearers settings should be as close as possible. Loephe Yarn master setting is given below

N -4.0 (nep)    :  DS-2.0 (short) :  LS-1.6 (short) :  DL-1.18 (long) :  LL-40  : (long) -DS-14%(thin)  :  -DL-40(thin)

Since loephe has a facility of class clearing. "C"s to be added in such  a way that  the following faults which are displayed in Loephe class clearing should be cleared.

 

A4,A3,B4,B3, B2(50%),C1,C2,C3,C4,D1,D2,D3,D4,E,F,G,H1(50%),H2,I1,I2

  • Count channel setting should be less than 7%
  • setting for cluster faults should be set such that, if a yarn produced without bottom apron, or damaged rubber cots is fed, it should be cut by the clearer
  • long thick faults in the cone yarn should be zero
  • long thin faults should be zero
  • If the waxing attachment is below the clearers, the clearers should be cleaned once in  a day
  • splice strength should be more than 75% of yarn strength
  • splice apperance should be good and all the splicers should be checked atleast once in a week
  • good qulity wax should be used
  • wax pick up should be around 0.1%
  • uniform application of wax to ensure uniform coefficient of friction (0.125 to 0.15)
  • uniform moisture in the cones is important, because coefficient of friction varies as a function of moisture
  • all wax rollers should rotate properly
  • repeaters  should be as low as possible, because this will affect the package quality
  • It is advisable to produce cones with 1.8 to 2.4 kgs
  • yarn tension in winding should not be very high
  • imperfection increase between ringframe and winding should  not be more than 30% for cotton combed yarns

 

GENERAL:

  • finished garments rejection should be less than 1%
  • yarn faults contribute to 25% of the rejections. Major yarn faults are

contamination

thick and thinks

Unevenness

periodicity

Stiff yarn - Higher TPI ( holes)

higher friction

high hairiness variation

mixed properties of yarn - "Barre"

Neps

white specs(immature fibres)

Kitties ( vegetable matters, dust content)

Lower elongation and elasticity

  • It is better to use cottons with less contaminations like Andy, SJV, Alto, etc
  • contaminations of length more than 20 mm should be nil in the yarn
  • as per japanese standard, the no of contamination per Kg of fabric should be less than 5
  • If cotton has contamination, it is compulsary to use manual picking on preopener lattice, cotamination detectors at blowroom, visual clearer(siro) at winding.
  • It is advisable to go to the supplier(cotton ginner) for quality - a concept of Japanese
  • 10 meter C.V% of yarn should be controlled and it should be as low as possible. This affects the fabric appearance

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