Sewing line setting

Note of Hasan sir, mbstu...

1. Sewing Line Setting

Setting up a Line

Before a new style is introduced to a production line, it is necessary to establish the operation
sequence, the time, the type of equipment and the attachments required to manufacture the order.
Management must have this information before the commencement of the order, so that the line
can be balanced and laid out in such a way to maximize productivity. Two methods can be used
to set up a line:

Method 1: Calculating the number of operators necessary to achieve a given production rate per
hour.
Method 2: Calculating the number of garments to be produced by a given number of operators.

Using either technique, certain information is required before commencing the calculations,
which are given below:
1. The number of operators in the line
2. A list of operations involved in making the garment
3. The standard minute values for each operation
4. Output required from a given group of operators

Further, the following information is required for balancing a line:
-The size of the group
- An operation sequence
-The standard time for the garment
- The total standard time for the garment

The method of calculating the line balance is as follows:
1. Add up the operation times for the whole of the style
2. Establish the percentage of each operation of the total time
3. Work out the theoretical balance using each operation’s percentage of the total number of
operators on the line.
4. Round of the theoretical balance to the nearest half an operator, either up or down
5. List the type of equipment required for each operation at the side of the rounded figure,
6. The equipment that has half operators could be combined with similar equipment to get full
operators.
7. If odd half operators are there, it should be rounded up.
8. The number of garments that would be produced per hour on each operation should be
calculated by multiplying the number of operators by 60(minutes) and dividing by the total
minutes for the style.

2. Definition of Standard Minute Value
Standard Minute is the time value arrived at for a task based on the average rate of output
which qualified workers will naturally achieve without over exertion provided that they know
and adhere to the specified method and provided that they are motivated to apply themselves to
their work.
- This definition is written in the ILO work study book.

Operation cycle time or average time, taken by an operator completing an operation is not the
Standard minute value. SMV is the given time that should be taken to complete operation if she
works at 100% performance level. SMV of the same operation will be different if the working
condition is changed – like operator using a different machine, the operator sews a bigger
component, an operator using attachment and work-aids when sewing a garment. Most
importantly, movement and motions involved in performing a task.

SMV calculation method
You can calculate garment SMV using SMV calculation software or through time study method.
Standard minute value calculation method using Time Study is explained in this article with an
example. First, you measure operation wise SMV. Then SMV of all operations in style are
combined to calculate total SMV of a garment.

In time study, you capture the observed time of the selected operation. You rate operator
performance in the work. You use standard allowances for different types of machines, bundle
allowance and contingency allowances.

Steps for calculating SMV

1. Record observed time.

Following the Time Study procedure, you conduct Time Study for a selected operator and on the
selected operation.

2. Convert observed time into Basic time using this formula.

The observed time for the same operation done by two different operators might be different.
Our objective is to establish the standard for the selected operation. So, for the levelling of the
observed time, it is multiplied by the rating factor. The new time is called as basic time.

Basic Minute =(Observed time in minute x Performance Rating)
3. Know the applicable allowances.

3. When an operator will be working there would be changes of a machine breakdown, they may
need to change the needle, replace empty bobbin, change thread spool, may need of threading
needle. There will be personal needs and fatigue allowance. For all these allowances, some
amount of time will be consumed from the operator’s standard time. To estimate more practical
SMV allowances are added to the basic time.

Normally, in progressive bundle system, garment components reached to an operator in bundle
form. For every bundle, the operator spends a few minutes in opening the bundle and tying it. So,
you need to add bundle allowance as well where applicable.

4. Calculate Standard minute

Add machine allowance, bundle allowance and other allowances to the basic time to calculate
standard minute.

Standard Minute Value = (Basic minute + Bundle allowances + machine allowance + personal
fatigue allowances).
Normally, when SMV is measured through time study method, the operation cycle is broken
down into operation elements and observed time is captured element-wise. Machine allowances
are added only to machine elements.

Also, note that bundle allowance is distributed across the pieces in a bundle. If bundle allowance
is 60 seconds for a 10 pieces bundle, bundle allowance would be added as 6 seconds to the basic
time.

Example: Let’s say you are making a blouse. You observed an operation and record its cycle
time. Following the above steps let’s derive SMV of an operation.

 Observe Time = 2 Minutes
 Rating of the operator = 90%
 Basic Time = (2 Minutes x 90%) = 1.8 Minutes [Why multiply Rating factor?]
 Machine allowance =10%
 Other Allowance = 10%
 Total allowance to add = 10% + 10% = 20%
 Allowance in minutes = 1.8 x 20% = 0.36 Minutes
Calculated SMV = (1.8 Minutes + 0.36 Minutes) = 2.16 minutes

In the operation bulletin, after measuring operation SMV, hourly and daily production capacity is

4. calculated. For further study on the capacity calculation, machine requirement calculation.

The Second method
The second method of establishing SMV is using PMTS software. For this method, you need to
know different motion codes and you need to study real-life operator hand and body movement.
You need to learn how to operate software for calculating sewing operation SMV. Once you
learn that you can measure SMV for any kind of operations whether it is cutting, pressing,
sewing, folding etc. (Essential thing you must have the software).

A presentation of standard time calculation using motion codes |

For your reference, establishing SMV using PMTS software, steps are shown in this post.


SMV calculation Software
If you want accurate SMV of garment (and other sewn product), you need a software to calculate
the SMV. Most of the SMV calculation software uses motion codes and predetermined times.
Few of the well-known SMV calculation software included

 GSDCost
 SewEasy
 ProSMV
 TimeSSD

5. Application of SMV (SAM value)
I have listed a few of the application of garment SMV.
1. SMV is used in factory capacity planning
2. SMV is the main data in the operation bulletin. Based on the operation SAM machine
requirement and manpower requirement is calculated. Further based on the machine requirement
machine layout and initial line balancing is done.
3. SMV is used for labour costing for garment production
4. SMV is used for performance benchmarking
5. SMV is used for efficiency calculation
6. SMV is used in Payroll calculation in piece rate payment. Earning is equal to garment produced
x operation SMV x rate per minute
7. When performance incentive is provided to the operators, SMV is essential for calculating
individual operator efficiency
8. Preparing operators’ performance-based skill matrix
9. Who is responsible for calculating garment SMV in a garment factory?
Normally, in the garment factory, industrial engineers or work-study officers calculate the
garment SMV. Further, they do production studies during bulk production on the floor and
validate garment SMV. SMV is measured in two stages – first at the time when buyer request
garment costing by sending a garment design or referring a garment sample. The second time,
SMV is measured prior to loading style into the production line. Further, the SMV is updated by
engineers after production study.


Definition of different terms used in SMV calculation process
Rating factor: Rating is a subjective comparison of any condition or activity to a benchmark,
based upon our experience. While the mechanics of time study record the time a task did take,
applying a rating will determine the time a task should take.
Cycle Time: It the time actually taken by an operator at the work. Cycle time is measured from
the time stamp of pick-up of the garment component to the next pick-up time stamp of an
operation cycle. The starting point of an operation cycle can be chosen by the engineer.
Normally the cycle time value is higher than the standard time.

Observed time: Here observed time is the same as the cycle time. The time recorded as it was
and operation cycle time calculated.

6. Formulas of Calculating SMV
Calculation of SMV in Garments
SMV = (Basic Time + Allocated Allowance)
The formula of Basic Time = Observe Time x Rating Factor
Basic Time
Basic time is the most likely time required to make garments considering observe time and
applicable rating factors.
Observe Time
Time is taken to do work when an observer is observing closely and record the worker’s work
speed.
Calculation of Observe Time = Total Cycle Time is divided by Number of Cycle
Cycle Time
Cycle Time is the time between starting a garment manufacturing and finishing of those
garments.
Rating Factor
The rating factor is assigned based on an evaluation of worker performance which is conducted
through eye judgment. A worker can be fast, slow and rating is on a scale of 100% to lower.
Costing SMV is calculated for sending SMV information to buyers. Normally 5% additional
time is added with the actual SMV.
Costing SMV = Actual SMV + (Actual SMV x 5%)

7. Calculation of Capacity of Single Operator in Garments
 If an operator works for 10 hours a day
 30 minutes to make a product
Capacity = (1 operator x 10 hours x 60 minutes)/30 Minutes = 20 Pieces of Garments by an
operator
If you assign 100 operators then your capacity will be = 100 operators x 20 pieces = 2000 pieces
a day
Calculation of Efficiency Percent
 SMV 22 Minutes
 Working Hours 10 a Day
 Number of Operators 100 person
 Actual Production 2000 pieces
Efficiency (%) = (2000 pieces x 22 minute)/(100 operators x 10 hours x 60 minutes) x 100 =
73.33%
whereas,
Target = (10 hours x 60 minutes x 100 operators)/smv 22 minutes = 2727 Pieces of garments

8. SMV of Different Garments Manufacturing
1. SMV of Men’s Long Sleeve Shirt is 23.15
2. SMV of 5 Pockets Long Pant is 20.14
3. SMV of T-Shirt is 8.41
4. SMV of Cargo Pant is 36.28
5. SMV of Polo Shirt is 10.39
6. SMV of Trouser is 8.13
7. SMV of Chino Short Pant is 37.42
8. SMV of Cargo Short Pant with Bone Pocket is 31.92
9. SMV of Cargo Short Pant without Bone Pocket is 24.06
10. SMV of Cargo Crop Pant is 30.74
11. SMV of Men’s Chino Pant is 24.15
12. SMV of Nano Chino Pant is 28.93
13. SMV of Leggings is 4.64
14. SMV of Blouse Manufacturing is 4.73
15. SMV of Hoodies Manufacturing is 15.99
16. SMV of Jogger is 19.61
17. SMV of Lingerie is 4.52
18. SMV of Shimmer Dress is 17.60
19. SMV of Ladies Overall is 32.93
20. SMV of Kids Overall Hoodie is 21.60
21. SMV of Brooke Short Pant is 9.32
22. SMV of Brooke Skirt is 7.90
23. SMV of Brooke Hoodies is 15.66
24. SMV of Cody is 28.14
25. SMV of Chino Pant is 36.86
26. SMV of Blazer is 21.85
27. SMV of Shirt Manufacturing is 33.84
28. SMV of Jacket Manufacturing is 44.97
29. SMV of Garments (Pant) Finishing Process is 9.05
1. How to calculate hourly production target for an individual operation
2. How to calculate hourly production target for a production line.
Hourly production target calculation is a part of an operation bulletin preparation and daily
production report. In an OB production target is calculated for each operations.

Following formula is used to calculate hourly target.

9. Hourly production target = (60 / Operation SAM)

An hour is equal to 60 minutes. Divide the 60 by the operation SAM. The end result of this
calculation tells you the number of pieces can be produced per hour, which is the hourly
production target for the selected operation.

Let’s take an example. SAM of an operation is 0.5 minute. Hourly production target would be
=(60/0.50) =120 pieces

Note: This target is calculated at 100% efficiency. In case you want to plan hourly production
target at particular percentage, multiply the above by individual operator efficiency.

Let’s say skill level of that operator is 80% efficiency, in that case production target would be

(60/0.50)*80% =120*80% =96 pieces

The information you need for calculating hourly production target are
1. Standard time (SAM) of the operation
2. Average efficiency of the line
Calculation of Hourly production target of a line
On the other hand for calculating hourly production target for a production line use the following
formula

Hourly Production Target of a line =((60 * No. of operators working in a line * Line efficiency
%) /Garment SAM)

If you need to calculate daily production target of a line, just multiply the hourly line target by
shift hours.



Machine Layout plan of a Polo T-shirt: In a machine Layout plan some information is listed
by the following table;



SL.
No.
Name of
Operation
Cycle
Time
Calculated
Production
Target/Hr. M/C Type
M/C
Required
Worker
Required

10. 1
Care Label
Attach With
Back Part
0.28 214 180 SNL 1 1
2
Placket & Body
Part Matching
0.30 200 180 MNL - 1
3
Placket Attach
Positioning
Marking
0.30 200 180 MNL - 1
4 Placket Rolling 0.32 188 180 SNL 1 1
5
Placket Attach
With Front Part
0.38 158 180 SNL 2 2
6
Placket Edge Cut
& Tack
0.25 240 200 SNL 1 1
7
Half Moon Cut
& Iron
0.45 133 180 IRON 2 2
8
Main & Size
Label Attach
0.35 171 180 SNL 2 2
9
Half Moon
Attach With
Back Part
0.45 133 180 SNL 2 2
10
Front And Back
Part Matching
0.18 333 250 MNL - 1
11 Shoulder Joining 0.33 182 180 OL 1 1
12 Collar Servicing 0.20 300 220 OL 1 1
13 Collar Making 0.18 333 250 MNL - 1
14
Collar Attach
With Tape
0.36 167 180 SNL 2 2
15 Back Tape Top 0.30 200 180 SNL 1 1

11. Stitch
16
Lower Placket
Close
0.20 300 240 SNL 1 1
17
Upper Placket
Top Stitch
0.20 300 240 SNL 1 1
18
Placket Box
Stitch
0.32 188 180 SNL 1 1
19 Cuff Joining 0.42 143 180 OL 2 2
20 Cuff Top Stitch 0.22 273 230 FL 1 1
21
Sleeve Pair
Matching With
Body Part
0.38 158 180 MNL - 2
22 Sleeve Joining 0.42 143 180 OL 2 2
23
Arm Hole Top
Stitch
0.30 200 180 FL 1 1
24
Bottom Hem
Stitch
0.32 188 180 FL 1 1
25 Side Split Tack 0.27 222 180 SNL 1 1
26
Side Split
Rolling & Top
Stitch
0.47 127 180 SNL 1 1
27 Side Seam 0.57 105 180 OL 2 2
28
Sleeve Close &
Open Tack
0.37 162 180 SNL 2 2
29
Button Hole
Creating At
Upper Placket
0.30 200 180 BH 1 1

12. 30
Button Attach
Positioning Mark
At Lower
Placket
0.20 300 240 MNL - 1
31
Button Attach
With Lower
Placket
0.25 240 190 BA 1 1
32 Button Push 0.18 333 250 MNL - 1
33 Final Thread Cut 0.30 200 180 MNL - 1

Total Cycle
Time
10.32

34 44

Table 1: Machine Layout plan of a Polo T-shirt.


Generally, a machine layout plan is made by following an operation breakdown. Because
from an operation breakdown, we get the proper idea about which part will join one after another
and select the machine for that operation. We have also known how many machine and workers
need for each operation from the machine layout plan.


Operation Bulletin of a Polo T-shirt: Operation bulletin of a Polo T-shirt has divided into 3
parts;
1. Sewing and production data.
2. Machine requisition data.
3. Manpower requisition data.
1. Sewing and production data: In sewing data included SMV of Sewing and manual
operation, production target per hour at 80%, 90%, and 100% efficiency.


Operation Bulletin of Sewing Data
Sewing Operation SMV 8.30 min.

13. Manual Operation SMV 2.02 min.
Production Target at 80% efficiency 1423 pcs
Production Target at 90% efficiency 1601 pcs
Production Target at 100% efficiency 1779 pcs

Table 2: Operation Bulletin of Sewing Data.


2. Machine requisition data: In machine data included types of machine and no. of machine
required for this garment production.


Operation Bulletin of Machine Data
Name Of Machine Requisition
OL – overlock 7 m/c
SNL – Single needle lock stitch 20 m/c
FL – Flat lock m/c 3 m/c
BH – Button Hole m/c 1 m/c
BA – Button Attach m/c 1 m/c
Iron m/c 2 m/c
Total 34 m/c

Table 3: Operation Bulletin of Machine Data.


3. Manpower requisition data: In manpower data included no. of the operator and
helper required for this garment production.

14. Operation Bulletin of Manpower Data
Operator 33
Helper 9
Total 44

Table 4: Operation Bulletin of Manpower Data.