A guide to calculations relating to yarn and cloth and all processes of weaving.It includes reed count, reed width, Maximum EPI for particular count, weave density, crimp percentage, cloth cover factor etc


In this page

  1. Some important Weaving Calculations

Some important Weaving Calculations

  1. Reed Count
    It is calculated in stock port system.No. of dents in 2 inches is called Reed Count.
    Reed Count = EPI/(1 + Weft crimp %age)
  2. Reed Width
    Reed Width = Cloth Width *(100+ weft crimp %age)/100
  3. Crimp Percentage
    Crimp %age = {(Warp length - Cloth length)/Cloth Length}* 100
    Crimp %age = {(Warp width - Cloth width)/Cloth width}* 100
  4. Cloth Cover Factor
    1. Cloth Cover Factor = Wp.C.F +Wt.C.F. - {(Wp.C.F. - Wt.C.F)/28}
  5. Maximum EPI for particular count
    1.  
    2. other design = (Ends /Repeat * 1/Yarn Diametre)/ (No of intersections/repeat+ ends/repeat)
  6. Warp Density

    •                             = <350
    • Weave Density = 50+{(Warp Density - 100) * F.D - 100} /{(Weft Density - 100)* F.D - 100}
    • Effective Weave Density = W. D x K of loom width x K of Design
                                           = < 72
    Wp / filling - K  Loom Width - K  Weave Design - K
    Cotton = 1.00 140 cm - 0.99 Plain1/1 = 1.00
    Polyester/Cotton = 1.03 180 cm - 1.00 Twill 1/2 = 0.87
    Viscose Filament = 1.17 190 cm - 1.01 Matt, Gabardine 2/2 = 0.82
    Polyester Filament = 1.22 220 cm - 1.02 Drill 1/3 = 0.77
    250 cm - 1.08 Satin 1/4 = 0.69
    330 cm - 1.15
    360 cm – 1.20
  7. To change the count and the number of thread / inch , keeping the same denseness of fabric
    To change the count without altering the denseness of the fabric
    EPI in Exp.cloth = (EPI in exp.Cloth2/EPI in given cloth) * count in given cloth
    To change the EPI without altering the denseness of the fabric
  8. Warp requirement to weave the cloth
    • Warp weight in grams /metre = {(Total Ends * 1.0936 * 453.59 * crimp %)/(840 * count)} * wastage %
    • Weft weight in grams /metre ={(R.S. in inches * 453.59 * PPI)/(840 * count)} * wastage % * crimp %
    • Cloth length in metres with given weft weight=( weft weight in kgs * weft count * 1848 * 0.9144)/(PPI * R.S in inches)

    For silk and Polyester
    • Warp weight in grams /metre ={(Total Ends * count (Denier) )/9000} * wastage % * crimp %
    • Weft weight in grams /metre = {(R.S in inches * count(Denier)* PPI)/9000}* wastage % * crimp %

    Allowance for count in bleached and Dyed fabric
    1.Count becomes 4%
    2. FinerDyed counts become max 6% Coarser

  9. Fabric Production Calculation
    • Loom Speed = Motor RPM * (Motor Pully Diametre)/(Loom Pully Diametre)
    • Loom Effeciency Percentage = (Actual Production/Calculated Production )* 100
    • Moisture Regain Percentage = {(Yarn Weight - Dried Yarn Weight)/Dried Yarn weight} * 100
    • Moistue Content Percentage = {(Yarn Weight - Dried Yarn Weight)/Yarn weight} * 100 
    • Type of Yarn Moisture Regain % Moisture Content %
      Cotton 8.50 7.83
      Jute 13.75 12.10
      Silk 11.00 9.91
      Rayon, Viscose 11.00 9.91
      Wool 17.00 14.50
      Nylon 4.20 3.78

    • Warp Weight in Kg = (Total Ends * Tape Length in metres)/(1693.6 * Warp Count)
    • Weft Weight in Kg = (R.S in centimetres * cloth length in metres * PPI )/(4301.14 * weft Count)
    • Cloth weight in GSM = {EPI/Warp Cout)+(PPI/Weft count)}* 25.6
    • oz (ounce ) per sq. yard = GSM(Grams per sq. metre)/34
  10. Material Measurement 
     To calculate the length of any rolled fabrics, this formula gives the nearest accuracy.
      L = {0.0655(D-d)(D+d)}/t 
     Where L = Length of material (Feet)    t = Thickness of fabrics (inches) 
               D = Outside diameter (inches)   d = Inside diameter (inches)

  11. Weight of yarn in a cloth
    The weight of cloth manufactured on looms depends upon the weight of yarns in thewarp and weft: ends/inch, picks/inch and the weight of size on the warp. Therefore,
     Cloth weight = Weight of warp + Weight of weft + Weight of size (All inlbs.)
    Where as Weight of warp in lbs. = (Total No. of Ends * Tape Length in Yards)/(840 * warp yarn count)

  12. Also