Knitting Technology Part 2 Elaboration of different controlling parameters having significant impact on knitting technology Dr Muhammad Mushtaq Mangat www.mushtaqmangat.org

Process control in weft knitting

  Fabric elasticity depends upon:   Type of fibers

  Number of wales per inch   Stitch length

  Relaxation/finishing route   Yarn linear density   Planner weight

Tightness Factor

  L is stitch length, K ranges from 1.29-1.6 [1]

Quality control in weft knitting

  Off machine by using HATRA course length tester and Shirley crimp tester.

  On machine by yarn speed and length meter

  Issues:

  Variation in tensions

  Variation in yarn thickness

Production Calculation   Gauge of machine= 20

  Diameter of machine=30

  Number of feeders= 90

  Stitch length 4mm

  Total number of needles=20*30*3.14=1884

  RPM= 20

  Yarn count= 20s

  Production day (20 hr) *.85 (efficiency)=

  =((((1884*90*20*60*20*4*.85)/1000)*1.0936)/(840*20))/ 2.2046=408 Kgs per day

Knitting Hal Requirements   Controlled environment in knitting hall (moisture and temperature)

  Machine maintenance,

  Quality of compressed air

  Skill of workers

  Yarn storage place and methods

  Fabric storage

  Lubricants quality

  Quality of needles and sinkers

  Fluff level in the environment

Knitting hall temperature and moisture

  Mayer and Cie, one of the largest and most aggressive knitting machine manufactures recommends maintaining 20 C° temperature and 65 % RH humidity in knitting hall.

  It is expected that 20-25% production of the knitting mill can be improved by putting an air conditioning plant.

  In addition to that 50% less faults and 50% less consumption (breakage) of needles and sinkers is expected.

  A healthy environment to workers, which keeps them healthy.

  And finally we have a neat, clean, free from fly and healthy environment, which definitely improver our productivity.

Cont…   No tripping of electronic parts, which is quite common

at high temperature

  Less breakage of needles due to low temperature

  Satisfied operator since environment is neat and clean along with suitable temperature and humidity

  Better knitted fabric quality due to less yarn breakage and low machine stoppage frequency

  Better health of workers

  Less yarn wastage

  Conducive environment for creativity

Moisture Free Compressed Air

  Cool and moisture free compressed air for knitting is required

  We can have following advantages of cool, free from contaminant in and dry air:

  Helps reduction in needle breakage

  Avoiding rust on machine

  Smooth running of machine

  Reduction in accidents

References

  [1] Anand, S.C., Technical fabric structures – 2. Knitted fabrics, in Handbook of Technical Textiles A.R. Horrocks, Anand, S. C., Editor 2000, Woodhead Publishing Ltd Cambridge.