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Sewing Thread Consumption

Sewing thread consumption refers to the requirement of thread per unit garment. Thread consumption is significant for cost constrain as well as uninterrupted production.


1. Factor affecting sewing thread consumption
Sewing thread consumption is affected by the following factors;
1. Stitch class
2. SPI
3. Seam types
4. Thickness of fabrics
5. Fabric plies in seams
6. Thread tension
7. Thread count
8. Quality of sewing thread
9. Machine options
10. Operators skills

2. Steps of sewing thread consumption
Steps of Sewing Thread Consumption


3. Methods of Thread Consumption
There are three methods generally used to calculate the amount of thread in a seam and hence the thread consumption in the sewn product:

1. By measuring the actual amount of thread consumed - It is accurate.
2. By calculation using thread consumption ratios - It is approximate
3. By using the thread consumption formula - It is better than 2nd option.

1. Measuring Actual Thread Consumed
A specified length of a given seam is measured and then the thread is pulled out of this length. We can use the amount pulled out of this specified length to calculate the ratio of thread consumed in the entire seam. By dividing the amount of thread by the seam length, we get the ratio of thread consumed. If we multiply this factor times the total length of the seam, we can determine the total thread consumed for that seam.

Example:
Length of seam = 100 cm (1 metre)
Stitch class 401 = 2-Thread Chain stitch
Length of seam for which thread is removed = 15 cm
Needle thread removed = 19.5 cm
Needle thread factor = 19.5/15 = 1.3
Looper thread removed = 62.0 cm
Looper thread factor = 62.0/15 = 4.1
Total Needle thread = 100 cm x 1.3 = 130 cm
Total Looper thread = 100 cm x 4.1 = 410 cm
Total thread consumed = 130 + 410 = 540 cm
Add 15% wastage* = 540 cm x 1.15 = 621 cm

Generally, 10% to 15% wastage of thread is added to the consumption derived. This wastage occurs due to shop-floor conditions like machine running, thread breakage, repairs, etc. The above example shows the total thread consumed for one type of stitch class in a garment. By following a similar procedure, you can calculate the thread consumed for different stitching operations in a garment.

2. Thread Consumption Ratios
The easier method is to use the generally applicable Thread Consumption Ratios for the various stitch types that are listed in the table below. By relating these ratios to the length of seams using each stitch type, total thread consumption can be calculated.

Stitch Class
Description
Thread Ratio
inch/ inch or cm / cm  
# of Needles
Needle Thread %
Under & cover Threads %
101
1 Thread Chain stitch
4.00
1
100
0
301
Lock stitch
2.50
1
50
50
304
Zigzag Lock stitch
7.00
1
50
50
401
2 Thread Chain Stitch
5.50
1
25
75
406
3 Thread Covering Stitch
18.00
2
30
70
407
4 Thread Covering Stitch
20.00
2
30
70
504
3 Thread Over edge Stitch
14.00
1
20
80
512
4 Thread Mock Safety Stitch
18.00
2
25
75
514
4 Thread Mock Safety Stitch
20.00
2
20
80
516
5 Thread Safety Stitch
20.00
2
20
80
602
4 Thread Covering Stitch
25.00
2
20
80
605
5 Thread Covering Stitch
28.00
3
30
70

Generally, 10% to 15% wastage of thread is added to the consumption derived. This wastage occurs due to shop-floor conditions like machine running, thread breakage, repairs, etc. The above example shows the total thread consumed for one type of stitch class in a garment. By following a similar procedure, you can calculate the thread consumed for different stitching operations in a garment.

Note:
a. The above ratios are arrived at with a stitch density of 7 stitches per cm (18 stitches per inch).
b. These ratios are the prescribed minimum in regular conditions and marginally vary with the factors affecting thread consumption.
c. A certain percentage of wastage is to be added to the above ratios as per shop floor conditions. It may vary from 10% to 15%.

3. Thread consumption equation
Thread consumption may be carried out by using an equation that is derived from stitch geometry for various stitch types. The equation is flexible and applicable to any given length of seam, they are shown for one inch only and may be multiplied by the length of the seam to determine the total thread consumed. The following variables are considered to develop a mathematical equation.

C
=
Consumption per inch
W
=
Width of seam
T
=
Thickness of materials
S
=
Stitch per inch
N
=
Stitch length in inch
N X S
=
1
(*)
=
2W+N assumes for cover thread


Stitch Types
Stitch Name
Equation
101
Single-thread Chain Stitch
C = 3 + 2TS
301
Lock Stitch
C = 2 + 2TS
401
Two-thread Chain Stitch
C = 4 + 2TS
406
Cover-seaming Stitch
C = 7 + 2S(T+W)
407
Cover-seaming Stitch for Attaching Elastic
C = 9 + 2S(3T+W)
504
3 Thread Over lock
C = 4S(W+T) + 5
514
4 Thread Mock Safety
C = 5 + 2S(3T+2W)
516
5 Thread Safety Stitch
C = 2S(2W+3T) + 9
*602
Cover Stitch
C = 8 + S(5W+4T)
*605
Cover Stitch
C = 10 + 2S(2W+3T)
*607
Flat Seaming Stitch
C = 12 + 4S(W+2T)        

Above equation developed for commonly used stitch types.

4. Sewing Thread Consumption for common items
Following is a list of thread consumption of different sewn garments. This list is based on typical garment construction.

Items
Thread consumption per Pc.
Meter
Yard
Blouse
120
130
Bra
55
60
Brief (Men's)
50
55
Business Suit trouser
300
330
Costume (2 pcs)
400
440
Jacket (Classic Nylon Padded)
500
545
Jacket (Denim )
450
490
Jacket (Twill)
450
490
Night Dress
200
220
Nylon Jogging Suit
500
545
Nylon Padded Jacket
350
380
Nylon Wind Breaker
300
330
Overall
400
440
Overall (Classic)
500
545
Pants (Denim 5 Pocket)
400
440
Pants (Long)
350
380
Pants (Long, Classic)
450
490
Panty
50
55
Payjama
200
220
Payjama Set
450
490
Polo shirt
180
195
Romper
350
380
Romper (Classic)
450
490
Sack coat/Blazer
190
210
Shirt (Woven, Classic Short sleeve)
150
165
Shirt (Woven, Classic,,Long sleeve)
175
190
Shirt (Woven, Full sleeve)
150
165
Shirt (Woven, Short sleeve)
125
135
Shorts
350
380
Shorts (Classic)
450
490
Skirt (Lined)
170
185
Skirt (Unlined)
110
120
Sweater
25
30
Sweat Shirt (Fleece)
280
300
Tank Top
50
55
T-shirt
125
135
Waist coat
70
75
Winter coat
265
290
Work Suit (2 pcs)
375
410


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