How to Calculate comprehensive guide on key garment production

 

"Step-by-Step Guide: How to Calculate Key Garment Production Metrics for Efficient Manufacturing"

1️⃣ Hourly Production Target

The hourly production target is the number of pieces a worker should produce in one hour.

Formula:

$$\text{Hourly Production Target} = \frac{60}{\text{SAM in minutes}}$$

• SAM = Standard Allowed Minute (time to make one garment).

• If multiple operators/machines:

$$\text{Hourly Production Target per Operator} = \frac{60}{\text{SAM}}$$

Example:

• SAM = 12 minutes

$$\text{Hourly Production Target} = \frac{60}{12} = 5 \text{ pieces/hour}$$

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2️⃣ Machine Productivity

Machine productivity measures output per machine per hour or day.

Formula:

$$\text{Machine Productivity (\%)} = \frac{\text{Actual Output}}{\text{Machine Capacity}} \times 100$$

Example:

• Machine capacity = 100 pcs/day

• Actual output = 90 pcs/day

$$\text{Productivity} = \frac{90}{100} \times 100 = 90\%$$

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3️⃣ SAM (Standard Allowed Minute)

SAM is the time required to complete one garment under standard conditions. It is calculated by time study or using predefined data.

Formula:

$$\text{SAM} = \text{Observed Time} \times \text{Rating Factor}$$

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4️⃣ SAM vs Cycle Time

• Cycle Time (CT): Actual time taken to produce a piece.

• SAM: Standard time expected for the piece.

Efficiency formula:

$$\text{Efficiency (\%)} = \frac{\text{SAM}}{\text{Cycle Time}} \times 100$$

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5️⃣ Pieces per Hour from Cycle Time

If you know cycle time, you can calculate production per hour.

$$\text{Pieces per Hour} = \frac{60}{\text{Cycle Time in minutes}}$$

Example:

• Cycle Time = 15 min

$$\text{Pieces per Hour} = \frac{60}{15} = 4 \text{ pcs/hour}$$

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6️⃣ Production Cost from SMV and Monthly Salary

• SMV (Standard Minute Value) = SAM in minutes for one piece.

• Wage per Minute = $\frac{\text{Monthly Salary}}{\text{Working Minutes per Month}}$

Formula:

$$\text{Production Cost per Piece} = \text{SMV} \times \text{Wage per Minute}$$

Example:

• SMV = 12 min, Salary = $300/month, Working min/month = 15000

$$\text{Wage per min} = \frac{300}{15000} = 0.02\$/min$$ $$\text{Cost per piece} = 12 \times 0.02 = 0.24\$/pc$$

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7️⃣ Overall Line Efficiency (OLE)

Measures how efficiently a line is producing compared to its capacity.

$$\text{OLE (\%)} = \frac{\text{Actual Output}}{\text{Target Output}} \times 100$$

• Target Output = SAM-based target for that time period.

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8️⃣ Non-Productive Time (NPT)

Time when workers/machines are not producing.

Formula:

$$\text{NPT (\%)} = \frac{\text{Non-Productive Time}}{\text{Total Time}} \times 100$$

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9️⃣ DHU (Defects per Hundred Units)

Measures quality defects.

$$\text{DHU (\%)} = \frac{\text{Number of Defective Pieces}}{\text{Total Pieces Produced}} \times 100$$

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🔟 DR% (Defect Rate %)

Similar to DHU but can include all defect types:

$$\text{DR (\%)} = \frac{\text{Total Defective Units}}{\text{Total Units Produced}} \times 100$$

🔟 SMV (Standard Minute Value)

Basic Formula:

$$\text{SMV} = \text{Observed Time} \times \text{Rating Factor} + \text{Allowance Time}$$

Where:

• Observed Time = Actual time measured for completing a task (usually in minutes)

• Rating Factor = Adjustment for worker efficiency (normal pace = 1, faster or slower = adjust accordingly)

• Allowance Time = Extra time added for personal needs, fatigue, machine delays, etc.

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Step-by-Step Calculation Example:

1. Observed Time = 10 minutes

2. Performance Rating Factor = 1.1 (worker is 10% faster than normal)

3. Allowance = 1 minute

$$\text{SMV} = 10 \times 1.1 + 1 = 12 \text{ minutes per piece}$$

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Alternative View (If using seconds):

$$\text{SMV (in minutes)} = \frac{\text{Time in seconds} \times \text{Rating Factor}}{60} + \text{Allowance in minutes}$$

Usage of SMV

1. Hourly Production Target:

$$\text{Hourly Target} = \frac{60}{\text{SMV}}$$

2. Production Cost per Piece:

$$\text{Cost per Piece} = \text{SMV} \times \text{Wage per Minute}$$

3. Line Efficiency (%):

$$\text{Efficiency (\%)} = \frac{\text{SMV}}{\text{Actual Cycle Time}} \times 100$$