Introduction
A loom is a contact point of all the processes (ginning, opening, carding, spinning, winding,
warping, sizing & beaming) of fabric production. These processes are done before weaving.
A loom can not be said machine but it is a device which is used to produce woven fabric. There are
various types of loom like Projectile loom, Rapier loom, Air jet & Water jet loom etc. The whole
process of weaving is done through several motions.
There are three main loom motion, which are- 1) Primary motion, 2) Secondary motion & 3) Tertiary
motion. So, calculation play an important role in weaving process. Some important production
calculation (Fabric specification, Weight of fabric, Loom production, Efficiency, Machine RPM etc.) of
Loom are discussed below.
Fig: Production calculation of loom
Some Important Conversions for Production Calculation of Loom
36 inch = 3 Feet = 1 Yard;
1 Meter = 1.0936 Yards;
1 Pound(lb) = 453.6 Gram = 16 Ounce (Oz);
1 Lea = 120 Yards;
840 Yard = 7 Lea = 1 Hank;
1 Pound (lb) = 7000 Grains;
1 Meter = 39.37 Inch;
1 inch = 2.54 cm;
1 cm = 10 mm;
1 Kg = 2.205 Pound (lb)
Mathematical Problems of Loom Production Calculation
Fabric weight calculation:
…………………………………………….EPI x PPI
1. Fabric Specification: ———————————————- x Fabric Width
…………………………………Warp Count x Weft Count
……Warp Count x Weft Count
Or, ———————————————- x Fabric Width
……………..EPI x PPI
………………………………………10 x 8
Example: Fabric Specification ———————- x 60”
……………………………………..70 x 50
Calculate the fabric weight of 1000 m.
Solution:
Warp Weight:
EPI = 70
Warp Count= 10
Fabric width = 60”
Total No of warp = 70 x 60 = 4200
Length of each end = 1000 m + 1000 x 3% [Crimp = 3%]
= 1030 m
Total Length of warp = 4200 x 1030 m
= 4326000 m
We know,
……….L x w
Ne = ————————
………W x l
Warp Length,
L = 4326000 m
Ne = 10
……………………………….L x w
Warp weight, W = ————————
………………………………Ne x l
….4326000 x 0.4536
= ——————————- kg
…..10 x 840 x 0.91
= 256.71 kg
Weft Weight:
PPI = 50
Weft Count = 8
Total no of weft = 50 x 39.37 x 1000 = 1968500
Fabric width = 60”
Length of each weft = 60” + 60 x 5% [crimp = 5%]
= 63” = 1.6 m
Total Length of weft = 1968500 x 1.6 m
= 3149600 m
…………………………L x w
We know, Ne = ————————-
………………………..W x l
Weft Length, L = 3149600 m
Ne = 8
……………………………..L x w
Weft Weight, W = ——————–
…………………………….Ne x l
…3149600 x 0.4536
= ——————————— kg
……8 x 840 x 0.91
= 233.62 kg
Now, Total Fabric Weight = Warp Weight + Weft Weight
= 256.71 + 233.62 kg
= 490.33 kg (Ans)
Example: Calculate the weight of yarn in fabric (warp & weft)
…20 x 22
—————- x 56” of 5000m fabric
…60 x 58
Solution:
In 5000 m fabric, weight of warp:
EPI = 60
Warp count = 20
Fabric width = 56”
Total no of warp = 60 x 56 = 3360
Length of each end = 5000m + 5000 x 7% [Crimp = 7%]
= 5350 m
Total Length of warp = 3600 x 5350 m
= 17976000 m
……………………….L x w
We know, Ne = ————————–
……………………….W x l
Length of warp, L = 17976000 m
Ne = 20
………………………………….L x w
Weight of warp, W = ————————-
…………………………………Ne x l
…17976000 x 0.4536
= —————————- kg
……20 x 840 x 0.91
= 533.35 kg
Weight of Warp yarn = 533.35 kg (Ans)
In 5000 m fabric, weight of weft:
PPI = 58
Weft Count = 22
Total no of weft = 58 x 39.37 x 5000
= 11417300
Fabric width = 56”
Length of each weft = 56” + 56 x 7% [crimp = 7%]
= 59.92” = 1.522m
Total Length of weft = 11417300 x 1.522 m
= 17377130.6 m
………………………..L x w
We know, Ne = ————————-
……………………….W x l
Weft Length, L = 17377130.6 m
Ne = 22
……………………………….L x w
Weft Weight, W = ———————
………………………………Ne x l
…17377130.6 x 0.4536
= ———————————– kg
……22 x 840 x 0.91
= 468.71 kg
Weight of weft yarn in 5000m fabric = 468.71 kg (Ans)
Production calculation of loom:
………………………………………………..PPM
1. Fabric Production in Meter = —————- x 60 x No of Loom x Efficiency
…………………………………………………PPI
……………………………………………………PPM
2. Production per hour per loom = —————–
…………………………………………………….PPI
Example: Calculate the fabric production in meter per shift of a weaving factory in which a day is
divided into two shifts. The factory has two weaving sheds, each consists of 15 rapier looms. The
produced fabric has following specifications-
….20 x 16
—————— 56” [Assume any necessary parameters]
…110 x 51
Solution:
Here, 1 Shift = 12 hrs
Each weaving shed consists of 15 looms
So, Total no of looms in two sheds = 15 x 2 = 30
PPI = 51
Assume, PPM = 200
M/C Efficiency = 90% = 0.9
………………………………………………PPM
Now, Fabric Production in Meter/Shift = —————– x 60 x 12 x No of Loom x Efficiency
……………………………………………….PPI
…200 1
= ——– x 60 x 12 x 30 x 0.9 x —————
….51 39.37
= 1936.38 meter/shift (Ans)
Example: Calculate the yarn consumption of a loom per hour running at 180 PPM for producing
…40 x 60
——————— x 56” fabric.
…72 x 48
Solution:
Here, PPM = 180
PPI = 48
……………………………………………PPM
Now production per hour per loom = ——————-
…………………………………………….PPI
…180 1
= ———- x 60 x ———- yds
….48 36
= 6.25 yards (Ans)
Example: Calculate the production of loom-
PPM = 350
PPI = 60
No of loom = 45
Time = 7 days
Efficiency = 90%
Solution:
………………350 90 1
Production = ——— x 60 x 24 x 7 x 45 x ——— x ————– meter/7days
…………….…60 100 39.37
= 60487.68 meter/7days (Ans)
Example: Find out production calculation of loom –
Crank shaft RPM = 60
No of Tappet = 3
PPI = 50
Efficiency = 80%
Solution:
PPM = Crank shaft RPM x No of Tappet
= 60 x 3 = 180
………………………….180 80 60
Loom Production = ————— x ———– x ————- yards/hour
………………………….50 100 36
= 4.8 yards/hour (Ans)
Example: Calculate the loom production –
No of bobbins = 250
Time = 30 days
Efficiency = 80%
PPM = 300
PPI = 82
Solution:
……………………………….300 x 60 x 24 x 30 x 260 x 80
Loom Production = ——————————————————- yds/30 days
…………………………………………..82 x 100 x 36
= 878048.78 yds/30 days (Ans)
Machine efficiency and RPM calculation:
…………………………………………………Motor Pulley Dia
1. Machine RPM = Motor RPM x —————————————–
………………………………………………….M/C Pulley Dia
……………………………………Real time utility x 100
2. Loom efficiency (%) = ———————————————–
………………………………………….Shift time
Example: Calculate the efficiency of loom-
PPM = 650
PPI = 58
No of loom = 10
Time = 35 days
Production = 110000 m
Efficiency, ⴄ = ?
Solution:
……………………650 x 60 x 24 x 35 x 10 x ⴄ
Production = ———————————————-
………………………….58 x 100 x 39.37
……Production x 58 x 100 x 39.37
ⴄ = ———————————————————
……….650 x 60 x 24 x 35 x 10
…110000 x 58 x 100 x 39.37
= ———————————————-
……650 x 60 x 24 x 35 x 10
= 76.77% (Ans)
Example: Calculate Machine RPM-
Motor RPM = 1440
Motor Pulley Dia = 3”
M/C Pulley Dia = 8”
Solution:
………………………………………………. Motor Pulley Dia
Machine RPM = Motor RPM x —————————————-
……………………………………………….Machine Pulley Dia
………………3
= 1440 x ——–
……………..8
= 540 (Ans)
Example: Calculate the loom efficiency and loom production-
Loom RPM = 700
PPI = 90
Time to mend warp breakages = 10 min
Weft breakages time = 5 min
Other stops = 10 min
Shift time = 8 hrs
Solution:
Total stoppage time = 10 + 5 + 10 = 25 mins
So real time utility = 8 hrs – 25 mins
= 7 hour 35 mins
= 7.583 hrs
…………………………….Real time utility x 100
Loom efficiency = —————————————-
…………………………………..Shift time
…7.583 x 100
= ———————–
………..8
= 94.78% (Ans)
………………………………. Loom RPM x 60 x Shift time x Efficiency
Loom Production = ———————————————————————
…………………………………………….PPI x 39.37 x 100
…700 x 60 x 8 x 94.78
= ———————————– meters
……90 x 39.37 x 100
= 89.87 meters (Ans)
The End
