Line Balancing

Assembly line balancing (ALB) is the process of assigning tasks to workstations in a production line to achieve optimal or near-optimal distribution of workload while respecting **precedence constraints** (order in which tasks must be performed) and **cycle time** (maximum time allowed per workstation, determined by demand). The primary goal is to **minimize idle time** and **maximize line efficiency** by evenly distributing task times across stations. Key concepts include: **task times** (time required for each task), **precedence diagram** (graphical representation of task dependencies), **cycle time (CT)** (e.g., CT = production time per day / required output), and **workstation allocation** (grouping tasks into stations). Common methods for solving ALB problems include: **Ranked Positional Weight (RPW)** (prioritizes tasks with the highest sum of following task times), **Most Following Tasks (MFT)** (prioritizes tasks with the most successors), **Coffman’s Algorithm** (heuristic for minimizing workstations), and **Kilbridge and Wester’s Method** (systematic approach for task assignment). Assumptions: Task times are deterministic, cycle time is fixed, tasks cannot be split, and precedence constraints are strict. Performance metrics include: **line efficiency** (percentage of total task time used productively), **balance delay** (percentage of idle time), and **smoothness index** (variability in station workloads). Practical considerations: Bottlenecks (stations with the highest workload) limit throughput, and flexibility (ability to reallocate tasks) is important for adapting to demand changes.