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Process control in warping-2
Efficiency of Warping Department
The following will calculate the efficiency of a warping
machine:
Let Speed in m/min= 300
Set length (m) = 18000
Yarn length on cone/cheese (m)= 54000Number of Ends/beam=
500
end breaks/400 ends/ 1000 m = 3
Time to mend a warp break (seconds) = 35Time to change a beam
(seconds) = 500
Time to change a creel (seconds) = 3000
Time loss due to miscellaneous causes/1000 m (seconds)= 25
Calculation
Running time R (s) = 1000x60/300 = 200
R is the uninterrupted running time in metersBreaks/running ends
in beam/1000 m = 3x500/400 = 3.75
Stoppage time /1000 m
(a) to mend breaks (s)= 3.75x35 =131 s(b) to change a beam
(seconds) = 500x1000/18000 = 28 s
(c) to change a creel = 3000x1000/54000 = 56 sec
(d) Miscellaneous time = 25 seconds
Therefore, S, the total stoppage time per 1000 meters (s)=
131+28+56+25 = 240 s
Therefore total efficiency = Rx100/(R+S)= 200x100(200+240) =
45.5 %
Expected Production per shift of 8 hours (m) =
(300x60x8x45.5)/100 = 65,500 m
Causes of Low efficiency or Low productivity
1. Increase in End breakage rate
The machine efficiency at warping is highly sensitive to the end
breakage rate
2. Improper utilisation of magazine creel
If the creel boy does not keep the magazine creel ready to be
used by the time the package in the
running creel are over, the efficiency will fall.
3. Reduction in Average Set-length
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Lower set lengths reduce the machine efficeincy at warping
4. Number of Tenters per Machine
The number of tenters per machine determine the time to mend an
end break. This is because by
the time the warper finds a broken end on the beam, the creel
boy brings the other end of thebroken yarn from the creel
5. Stops due to Machine Breakdown, shortage of cones etc.
If the stops due to machine breakdown, shortage of empty beams
or cones/cheeses etc. are high,
the actual efficiency of the machine will be lower than
calculated.
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Efficiency of Sizing
Efficiency of Sizing Department
The major causes of loss of machine efficiency are:
1. Creeling, which includes removing the exhausted beams,
mounting new beams, denting, leasing etc.
2. Replacement of weaver's beam on consumption
Efficiency in sizing
Let yarn count= 34
Set length on warper's beam= 18000 m
length of yarn on weavers beam= 1500m
Total number of ends= 4000
Full running speed= 50 m/min
No of lappers per 3000 ends per 1000 m = 3
Time to cut a lapper = 90 sec
Time to doff a beam and put new lease rods = 600 seconds
time to change a set = 6300 sec
Time loss/1000 m due to miscellaneous causes= 60 sec
Calculations
Sizing time of one beam with no stops : R = (1500x60)/50 = 1800
seconds
Lappers per beam of 1500 m per 4000 ends = 6
time lost in cuttin glappers per beam = 540 seconds
Number of weavers beam per set= 12
time lost per beam in a set change = 6300/12=525 seconds
time loss in beam doffing and leasing per beam = 600 seconds
Miscellaneous losses per beam of 1500 m = 90 sec
total time to size one beam = 3555 seconds
Machine efficiency = (1800 x 100)/3555 = 50.6%
