Sewing Thread Consumption and Numbering System
Consumption calculation of sewing thread:
Generally merchandisers are the responsible person in garment consumption and costing. So garment merchandiser need to control manufacturing costs of a garment. Sewing thread is one of the common accessories in the apparel industry. Propersewing thread consumption can save maximum wastage for an order. Several factors determine the extent of thread consumption in any sewn product, such as stitch type, seam type, material thickness; number of layers, construction and SPI (stitches per inch). However, these factors are not constant with the different style preferences. Hence, thread consumption is never standard for sewn product categories such as shirts, trousers and footwear.
Factors affecting sewing thread consumption:
There are two methods generally used to calculate the amount of thread in a seam and hence the thread consumption in the sewn product:
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 seam, we can determine the total thread consumed for that seam.
Example: 1 Calculate the sewing thread consumption in a 15 cm length 2 thread chain stitch (402).
Solution:
• Length of seam for which thread is removed = 15 cm
• If we assume the needle thread removed is of 19.5 cm length, then the needle thread factor can be calculated as follows:
Needle thread length
Needle thread factor = -------------------------------------------
Original stitch length
= 19.5/15
= 1.3
If we assume the looper thread removed is of 62 cm length, then the looper thread factor can be calculated as follows:
Needle thread length
Looper thread factor = -------------------------------------------------
Original stitch length
= 62.0/15
= 4.1
Hence, from this to calculate the thread consumed for any unit length of seam, for example, the thread consumption for 1 metre (100 cm) of stitch is,
Actual thread consumption = Length of the seam × Thread factor ratio
For 100 cm stitch the total needle thread = 100 cm × 1.3 = 130 cm
For 100 cm stitch the total looper thread = 100 cm × 4.1 = 410 cm
Total thread consumed = 130 + 410 = 540 cm
Add 5% wastage* = 540 cm × 1.05 = 567 cm
*Note: Generally, 5%–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.
Method 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 Table-1. By relating these ratios to the length of seams using each stitch type, total thread consumption can be calculated.
Here, the above ratios are arrived at with a stitch density of 7 stitches per cm (18 stitches per inch). These ratios are the prescribed minimum in regular conditions and marginally vary with the factors affecting thread consumption. A certain percentage of wastage is to be added to the above ratios as per shop floor conditions. It may vary from 5% to 15%.
Note: Even, the buyer / customer didn’t provide any information about the sewing machine details, most of the time the merchandiser need to aware of the garment operation breakup and the suitable machinery for that particular operation by so the merchandiser need to assume based on the previous experience with same or similar styles in the past time.
Example: Calculate the sewing thread consumption for order “AQC 5554” with 10750 garments and the measurements are provided in Table-2. For sewing purpose, 4 thread over lock and 3 thread flat lock machines were used. All the sewing threads are same colour. Assume the necessary other details and calculate the consumption.
Solution:
Since, the application area of flat lock and over lock machines were not provided, for the given measurement first draw a rough picture of the garment and mention the application area for better understanding. Below Figure shows the diagram of T-shirt with given measurements.
Consumption for over lock thread: = Shoulder length (A -B) + (Armscyle depth (D) × 4) + Side seam (E-D) + (Sleeve seam (I) × 2)
= 10.25 + (9 × 4) + (20 × 2) + (3.25 × 2)
= 92.75 inches, to convert into centimetres, multiply by 2.54
= 235.58 cm.
In general, 1 cm 4 thread over lock stitch consists of 18 cm sewing thread, in that 25% needle thread and 75% looper thread.
Hence, for 235.58 cm stitch, the consumption is,
= 235.58 × 18 = 4240.44 cm.
Consumption for flat lock thread: = (Sleeve Hem (F) × 4) + (Bottom hem (H) × 2)
= (6.25 × 4) + (29 × 2) = 83 inches = 210.82 cm
In general, 1 cm 3 thread flat lock stitch consists of 18 cm sewing thread, in that 30% needle thread and 70% looper thread.
Hence, for 210.82 cm stitch, the consumption is,
= 210.82 × 18 = 3794.76 cm
Since, all the threads are of same colour, no need for needle thread and looper thread calculations.
Hence, the total consumption per garment is,
= Over lock thread length + Flat lock thread length
= 4240.44 cm + 3794.76 cm
= 8035.2 cm / garment.
The consumption for total order quantity is,
= 8035.2 × 10750
= 8,63,78,400 cm or 8,63,784 metres.
Number of cones required to complete the order,
8,63,784
=-------------------
5000
= 172.756 or 173 cones
Sewing Thread Numbering System:
Thread sizes are communicated through various numbers and numbering systems which are derived by relating its unit length and weight.
Fixed Weight Systems:
In this system, unit weight is taken as fixed and its length is measured
Systems under fixed weight:
Fixed Length Systems:
In this system, unit length is taken as fixed and its weight is measured
Systems under fixed length:
Generally, Metric count is used to describe synthetic, spun and core spun thread while English count is used to specify cotton thread. Filament threads are normally expressed with Decitex or Denier.
References:
Generally merchandisers are the responsible person in garment consumption and costing. So garment merchandiser need to control manufacturing costs of a garment. Sewing thread is one of the common accessories in the apparel industry. Propersewing thread consumption can save maximum wastage for an order. Several factors determine the extent of thread consumption in any sewn product, such as stitch type, seam type, material thickness; number of layers, construction and SPI (stitches per inch). However, these factors are not constant with the different style preferences. Hence, thread consumption is never standard for sewn product categories such as shirts, trousers and footwear.
Factors affecting sewing thread consumption:
- Thickness of fabrics
- Plies of fabrics to be sewn
- Stitch type
- Stitch density
- Width of seam
- Garment size
- Design of the apparel
- Automatic thread trimmer of that machine
- Skill of the operator
- Quality of thread
There are two methods generally used to calculate the amount of thread in a seam and hence the thread consumption in the sewn product:
- By measuring the actual amount of thread consumed
- By calculation using thread consumption ratios
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 seam, we can determine the total thread consumed for that seam.
Solution:
• Length of seam for which thread is removed = 15 cm
• If we assume the needle thread removed is of 19.5 cm length, then the needle thread factor can be calculated as follows:
Needle thread length
Needle thread factor = -------------------------------------------
Original stitch length
= 19.5/15
= 1.3
If we assume the looper thread removed is of 62 cm length, then the looper thread factor can be calculated as follows:
Needle thread length
Looper thread factor = -------------------------------------------------
Original stitch length
= 62.0/15
= 4.1
Hence, from this to calculate the thread consumed for any unit length of seam, for example, the thread consumption for 1 metre (100 cm) of stitch is,
Actual thread consumption = Length of the seam × Thread factor ratio
For 100 cm stitch the total needle thread = 100 cm × 1.3 = 130 cm
For 100 cm stitch the total looper thread = 100 cm × 4.1 = 410 cm
Total thread consumed = 130 + 410 = 540 cm
Add 5% wastage* = 540 cm × 1.05 = 567 cm
*Note: Generally, 5%–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.
Method 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 Table-1. By relating these ratios to the length of seams using each stitch type, total thread consumption can be calculated.
 |
| Table-1: Thread consumption ratio for different stitch types and machines |
Note: Even, the buyer / customer didn’t provide any information about the sewing machine details, most of the time the merchandiser need to aware of the garment operation breakup and the suitable machinery for that particular operation by so the merchandiser need to assume based on the previous experience with same or similar styles in the past time.
Example: Calculate the sewing thread consumption for order “AQC 5554” with 10750 garments and the measurements are provided in Table-2. For sewing purpose, 4 thread over lock and 3 thread flat lock machines were used. All the sewing threads are same colour. Assume the necessary other details and calculate the consumption.
 |
| Table-2: Measurements of order “AQC5554” |
Since, the application area of flat lock and over lock machines were not provided, for the given measurement first draw a rough picture of the garment and mention the application area for better understanding. Below Figure shows the diagram of T-shirt with given measurements.
 |
| Figure: T-shirt picture with measurements marked for order “AQC 5554” |
= 10.25 + (9 × 4) + (20 × 2) + (3.25 × 2)
= 92.75 inches, to convert into centimetres, multiply by 2.54
= 235.58 cm.
In general, 1 cm 4 thread over lock stitch consists of 18 cm sewing thread, in that 25% needle thread and 75% looper thread.
Hence, for 235.58 cm stitch, the consumption is,
= 235.58 × 18 = 4240.44 cm.
Consumption for flat lock thread: = (Sleeve Hem (F) × 4) + (Bottom hem (H) × 2)
= (6.25 × 4) + (29 × 2) = 83 inches = 210.82 cm
In general, 1 cm 3 thread flat lock stitch consists of 18 cm sewing thread, in that 30% needle thread and 70% looper thread.
Hence, for 210.82 cm stitch, the consumption is,
= 210.82 × 18 = 3794.76 cm
Since, all the threads are of same colour, no need for needle thread and looper thread calculations.
Hence, the total consumption per garment is,
= Over lock thread length + Flat lock thread length
= 4240.44 cm + 3794.76 cm
= 8035.2 cm / garment.
The consumption for total order quantity is,
= 8035.2 × 10750
= 8,63,78,400 cm or 8,63,784 metres.
Number of cones required to complete the order,
8,63,784
=-------------------
5000
= 172.756 or 173 cones
Sewing Thread Numbering System:
Thread sizes are communicated through various numbers and numbering systems which are derived by relating its unit length and weight.
Fixed Weight Systems:
In this system, unit weight is taken as fixed and its length is measured
Systems under fixed weight:
- English Count (Ne) = Number of hanks of 840 yards/lb
- Metric Count (Nm) = Number of hanks of 1,000 meters/kg
Fixed Length Systems:
In this system, unit length is taken as fixed and its weight is measured
Systems under fixed length:
- Denier = Weight in grams of 9,000 meters
- Tex = Weight in grams of 1,000 meters
- Decitex = Weight in grams of 10,000 meters
Generally, Metric count is used to describe synthetic, spun and core spun thread while English count is used to specify cotton thread. Filament threads are normally expressed with Decitex or Denier.
References:
- Apparel Merchandising by R. Rathinamoorthy and R. Surjit
- Garment Merchandising by M.A. Kashem
- https://clothingindustry.blogspot.com/2018/03/sewing-thread-consumption-calculation.html
- https://textilecalculation.blogspot.com/2015/05/sewing-thread-consumption-formula-with.html
