[LAB SPT 2025] MODUL 5 - LINE BALANCING

Line Balancing Overview and Data Preparation
📌 Line balancing is a production management technique to calculate machine and tool balancing across work stations to achieve optimal production efficiency, ensuring on-time production.
⚙️ Three methods for line balancing covered are: Rank Positional Weight (RPW), Largest Candidate Rule (LCR), and Region Approach (RA).
📊 Key data required for calculation includes the precedence diagram (derived from OPC) and cycle time data (from Module 1), with an added "Operation" column (A, B, C, etc.).

Cycle Time Calculation (TC) and Determination
⏱️ The Theoretical Cycle Time ($\text{TC}$) is calculated as: $\text{Effective Work Time} / \text{Production Capacity}$.
8️⃣ Effective work time is calculated using 8 working hours/day, 60 minutes/hour, and 25 working days: $8 \times 60 \times 25 = 12,000$ minutes.
🔀 If any single operation's cycle time is greater than the calculated $\text{TC}$ (e.g., $\text{TC}=32$ minutes, but operation $\text{K}=150$ minutes), the largest cycle time (150) must be used as the effective $\text{TC}$ for station assignment.

Method 1: Rank Positional Weight (RPW)
🔗 This method requires constructing a predecessor matrix using values 0 (no relation), 1 (forward relation), and -1 (backward relation) to define operational dependencies.
➕ Positional Weight is calculated by summing the times of the operation itself and all subsequent operations until the end of the process.
📊 Operations are ranked based on this weight (highest weight = Rank 1), followed by calculating $\text{M}\mu$ (theoretical number of stations: Total Cycle Time / $\text{TC}$).

Method 2: Largest Candidate Rule (LCR)
➡️ Unlike RPW, LCR directly sorts operations based on their cycle times from largest to smallest, using this ranking for station assignment.
⚖️ Workstation loading aims to reach the $\text{TC}$ limit (150) by sequentially adding ranked operations; operations that cause the cumulative time to exceed the limit are skipped for that station.

Method 3: Region Approach (RA)
🗺️ The precedence diagram is first divided vertically into distinct regions (Region 1, Region 2, etc.).
🥇 Operations within each region are ranked based on their largest cycle time; if times are equal, the operation appearing earlier in the precedence diagram is prioritized.
🧱 A critical difference: Loading in RA must be sequential by region package; operations cannot be skipped to meet the 150-minute limit if they belong to the same predefined package/region as the next operation.

Performance Metrics and Optimal Method Selection
📊 Line Efficiency ($\text{LE}$) and Balance Delay ($\text{BD}$) were found to be identical across all three methods because the Total Cycle Time (482) and $\text{TC}$ (150) remained constant: LE 80.33% and BD 19.67%.
📉 To determine the optimal method when $\text{LE}$ is equal, the Smoothness Index ($\text{SI}$) is used; the method with the smallest $\text{SI}$ (closest to 0) is preferred.
🏆 The Region Approach (RA) yielded the lowest Smoothness Index ($\text{SI} \approx 82.84$), making it the most optimal line balancing method for this scenario.

Key Points & Insights
➡️ Preparation is key: Ensure the Precedence Diagram and the Cycle Time/Operation Code table are accurately prepared from Module 1 data before calculation.
➡️ TC Override: Always use the maximum individual operation time (150 in this case) as the effective $\text{TC}$ if it exceeds the theoretically calculated $\text{TC}$ (32), as this forces consideration of necessary overtime/idle time.
➡️ Method Comparison: RPW/LCR allow skipping operations to fit the $\text{TC}$ limit, but RA requires strictly sequential package loading based on regional grouping, which can lead to different idle time distribution.
➡️ Optimal Selection Criterion: If $\text{LE}$ is equal across methods, choose the method resulting in the minimum Smoothness Index to minimize variation in workload across stations.

📸 Video summarized with SummaryTube.com on Jan 27, 2026, 11:47 UTC