How to Calculate SAM of a Garment?

SAM or Standard Allowed Minute is used to measure task or work content of a garment. For the estimation of cost of making a garment SAM value plays a very important role.

General Sewing Data (GSD) has defined set of codes for motion data for SAM calculation. There is also  other methods through which one can calculate SAM of a garment without using synthetic data or GSD. 

Method #1: Calculation of SAM Using Synthetic Data

In this method 'Predetermined Time Standard' (PTS) code are used to establish 'Standard Time' of a garment or other sewing products. 

Step 1: Select one operation for which you want to calculate SAM.

Step 2: Study the motions of that operation. Stand by side of an operator (experienced one) and see the operator how he is doing it. Note all movement used by the operator in doing one complete cycle of work. See carefully again and recheck your note if all movement/motion are captured and correct. (for example motions are like - pick up parts one hand or two hand, align part on table or machine foot, realign plies, etc.)

Step 3: List down all motion sequentially. Refer the synthetic data for TMU (Time measuring unit) values. For synthetic data you can refer GSD (without licence use of GSD code prohibited but for personal use and study one can refer GSD code and TMU values) or Sewing Performance Data table (SPD). Now you got TMU value for one operation (for example say it is 400 TMU). Convert total TMU into minutes (1 TMU=0.0006 minute). This is called as Basic Time in minutes. In this example it is 0.24 minutes.

Step 4: Standard allowed minutes (SAM) = (Basic minute + Bundle allowances + machine and personal allowances). Add bundle allowances (10%) and machine and personal allowances (20%) to basic time. Now you got Standard Minute value (SMV) or SAM. SAM= (0.24+0.024+0.048) = 0.31 minutes.

I like to refer you an article Secret Behind Calculation of Machine Time in SAM for better understand of SAM calculation. 

Method #2: Calculation of SAM Through Time Study

Step 1: Select one operation for which you want to calculate SAM.

Step 2: Take one stop watch. Stand by side of the operator. Capture cycle time for that operation. (cycle time – total time taken to do all works needed to complete one operation, i.e. time from pick up part of first piece to next pick up of the next piece). Do time study for consecutive five cycles. Discard if found abnormal time in any cycle. Calculate average of the 5 cycles. Time you got from time study is called cycle time. To convert this cycle time into basic time you have to multiply cycle time with operator performance rating. [Basic Time = Cycle Time X performance Rating]

Step 3: Performance rating. Now you have to rate the operator at what performance level he was doing the job seeing his movement and work speed. Suppose that operator performance rating is 80%. Suppose cycle time is 0.60 minutes. Basic time = (0.60 X 80%) = 0.48 minutes

Step 4: Standard allowed minutes (SAM) = (Basic minute + Bundle allowances + machine and personal allowances). Add bundle allowances (10%) and machine and personal allowances (20%) to basic time. Now you got Standard Minute value (SMV) or SAM. SAM= (0.48+0.048+0.096) = 0.624 minutes.

Role of the SAM Value in Production Planning and Control

SAM value of a garment is defined as how much time it would take to complete a garment in sewing. This is also known as garment work content and standard minutes.

key roles of PPC department

• Determining capacity of the factory and capacity of the individual sewing lines in terms of how many pieces (product specific) factory can make in a certain time period with existing machines capacity. 
• Order booking based on factory capacity for different types of products
• Allocating of styles to the lines
• Determining production lead time for each orders (styles)
• Process scheduling
• Production execution and monitoring 

Roles of SAM Value in Production Planning includes

1. Line Capacity Calculation: The scientific method of calculating production capacity of a line (in production pieces per day) is to use standard time (SAM) of a garment. So, to determine production capacity of a line (for specific products) in pieces you need to know garment SAM. 

2. Lead Time Calculation: Based on the production capacity, order allocation is done for different lines. A planning guy also need to calculate how long a style would run in a line if loaded in a single line. If you need to complete the order in less time, calculate how many lines to be considered for an order.

3. Order booking: During order booking, you need to consider capacity availability in a certain period. In such cases you can use how many minutes you need to make the new orders using garment SAM value and compare the same with how many production minutes are available in your factory for the defined period.

4. Process Scheduling: Time and action calendar or production process scheduling of each order is done by planning department. Again to schedule a list of tasks, you need to know capacity of each process per day (or a predefined period). Based on the capacity of each process you allocate no. of days for the process. Like for sewing department, you determine sewing capacity of your line (or multiple lines) and according to that you set how many days to be given to sewing department for production.

5. Order Execution and Production Monitoring: Standard minutes help planners to set target for sewing lines. Mutually agreed and calculated target given to line supervisors. On daily basis when you check production status you can compare actual production with target production. In case production is getting delayed you can push production team based on given target.

6. Labor Cost Estimation: One most important task is labor cost estimation of a specific order. To estimate how much labor cost to be considered for an order (style), you can’t make labor costing without having garment SAM value.

All the above six points is proving that garment SAM plays a big role in production planning and controlling function in garment industry.

How to Make Production Plan Without SAM Value?

Yes, there is a way to perform production planning tasks without garment SAM value.

The alternative way is calculating machine productivity to estimate line capacity as well as your factory capacity. If one know the procedure and formula of calculating productivity of the production floor, can find machine productivity easily. Later this productivity data would be considered as base of production planning. 

Method of calculating Machine productivity:

Machine productivity is defined as number of units produced per machine in a given time period.

Machine productivity = (Total production of a line in a day / No. of machines in the line) pieces per day per machine 

For example, suppose a line of 35 machines has produced 280 pieces per day (8 hours shift day). Machine productivity of the line 
= 280/35 pieces per machine per 8 hours day 
= 8 pieces per machine per 8 hours day

Finding daily line output data and machine numbers would not be a difficult job to anyone. Just for your information - style to style productivity will vary depending on work content of the style. So, you can prepare a database of the machine productivity for the previously produced styles. You can use historical data while required and update your machine productivity after each style gets over.

How to use productivity data in Production Planning?

Factory capacity Calculation:

Suppose machine productivity of your factory for ladies blouse is 6 pieces per machine per 8 hours shift and you have total 400 machines in your factory. So daily production capacity of your factory for ladies blouse would be equal to 400*6 pieces or 2400 piece per day (8 hours shift).

Factory capacity calculation formula of a given product

Factory capacity  (in pieces) = (Machine productivity * No. of running machines in your factory)  

Other planning related tasks those can be performed using factory capacity and line capacity figures are as following -

• Lead time calculation
• Order booking  
• Order scheduling
• Cost per piece

You can also measure line capacity using labor productivity data. But machine number in a factory is more stable than manpower (labor).