Line Balancing is a technique in production and operations management that involves allocating tasks among different workstations in an assembly line so that each workstation has roughly equal work content. The main goal is to minimize idle time, reduce bottlenecks, and maximize efficiency of the entire production system.
In simple terms, line balancing ensures that no workstation is overloaded or underutilized.
- The total amount of work on a line is divided into different tasks.
- Tasks are assigned to workstations that allow the work to be performed in a feasible sequence.
- Line balancing ensures that each work station gets approximately equal amount of time.
- Cycle time is determined by customer demand and represents the maximum time allowed at each workstation to complete its tasks.
- Line balancing is less common in continuous process industries but can still be applied where tasks are sequential and discrete.
Key Concepts and Definitions
| Term | Description |
|---|---|
| Workstation | A physical location on the assembly line where a specific task is performed. |
| Cycle Time | The maximum time allowed at each workstation to complete its assigned tasks. |
| Takt Time | The rate at which products must be produced to meet customer demand. |
| Idle Time | Time during which a workstation is not performing any task. |
| Balancing Loss | The total idle time across all workstations in relation to total available time. |
🛠️ Example: Assembling a Toy Car
🧾 Tasks:
| Task | Description | Time (min) | Predecessor |
|---|---|---|---|
| A | Attach wheels | 2.0 | — |
| B | Fix body | 3.0 | A |
| C | Paint car | 2.0 | B |
| D | Add stickers | 1.0 | C |
🔢 Step 1: Total Task Time = 2 + 3 + 2 + 1 = 8 minutes
⏱️ Step 2: Assume cycle time = 4 minutes
🚉 Step 3: Minimum Workstations = 8 / 4 = 2
🧩 Step 4: Assign Tasks to Workstations
Workstation 1:
-
A (2.0)
-
B (3.0) → Total = 5.0 ❌ (too much)
Try: A + C = 2 + 2 = 4.0 ✅
But C depends on B → Invalid
So:
-
A (2.0)
-
B (3.0) → Total = 5.0 ❌
Only A fits here
✅ Assign:
-
WS1: A (2.0) + CANNOT add B
-
WS2: B (3.0) + D (1.0) → Total = 4.0
But C still remains. So try:
WS1: A (2.0) + B (3.0) = 5.0 ❌
Try this final combo:
✅ WS1: A (2.0) + C (2.0) = 4.0
✅ WS2: B (3.0) + D (1.0) = 4.0
Oops! But B must come before C.
So correct order is:
✅ WS1: A (2.0) + B (3.0) = 5.0
✅ WS2: C (2.0) + D (1.0) = 3.0
✅ Final Workstation Assignment:
| Workstation | Tasks | Time |
|---|---|---|
| WS1 | A, B | 5.0 |
| WS2 | C, D | 3.0 |
📊 Efficiency:
Efficiency = [8 / (2 × 5)] × 100 = 80%