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
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
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.
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).
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)
|
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
|
thanks
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