Line Balancing | Management Optional Notes for UPSC PDF Download

Introduction

• Line balancing is a valuable tool in production, aimed at optimizing production lines to accommodate both external and internal variations. This strategy involves establishing a planned production rate for required materials within a specific timeframe. 
• Successful line balancing ensures that each segment of the production line can meet its production quota within the given timeframe using available production capacity. It enhances the throughput of assembly lines and work cells while reducing manpower requirements and expenses.

Distinction between Line Balancing and Assembly Line Balancing:

• While similar in concept, line balancing and assembly line balancing have distinct characteristics. Assembly line balancing involves the assembly of different parts, typically across multiple production lines. In contrast, traditional line balancing typically focuses on a single production line.
• Assembly line balancing, since its inception by Henry Ford, has been a significant optimization problem in industrial settings, yielding substantial economic benefits when implemented optimally.

Types of Line Balancing

• Static Balance: Static balance refers to long-term differences in capacity over extended periods, resulting in underutilization of workstations, machines, and personnel.
• Dynamic Balance: Dynamic balance pertains to short-term differences in capacity, typically over minutes to hours, arising from changes in product mix and variations in work time.

Objectives of Line Balancing:

The primary objective of line balancing is to align the output rate with the production plan, ensuring on-time delivery and preventing the accumulation of excess inventory. Johnson's articulation of the line balancing problem emphasizes the allocation of non-divisible tasks to assembly stations, with a focus on minimizing the number of required stations.

Implementation and Benefits

Line balancing serves as a common practice to address issues encountered in assembly lines, aiming to reduce imbalances between workers and workloads to achieve the desired production rate. This is achieved by equalizing the workload across stations and assigning an optimal number of workers to each workstation. Job elements are divided into smaller portions to maintain consistent production rates, facilitating efficient production operations.

Operating Conditions in Line Balancing

Line balancing operates within two primary conditions:

• Precedence Constraint: Products must complete necessary tasks at each station before progressing to the next station. This constraint ensures that certain parts are performed before others and prevents crossing over to other stations prematurely.
• Cycle Time Restriction: Each workstation has a maximum allowable cycle time, varying across different workstations.

Objectives of Line Balancing:

The primary objectives of line balancing are as follows:

• Manage workloads among assemblers.
• Identify bottleneck locations.
• Determine the number of workstations required.
• Reduce production costs.
• Minimize idle time by efficiently assigning tasks to each workstation.

Key Terms in Line Balancing Technique:

Several terms are crucial in assembly line balancing:

• Cycle Time: The maximum time allowed at each station, indicating the frequency at which the production line can generate products with existing resources.
• Lead Time: The cumulative production time along the assembly line.
• Bottleneck: A delay in transmission that slows down the production rate, typically resolved by balancing the lin
• Task Precedence: The sequence in which tasks are carried out, ensuring compliance with assembly line rules.
• Idle Time: Periods when the system is available but not in use.
• Productivity: The ratio of output to input, influenced by factors such as worker skills, job methods, and machine usage.
• Takt Time: The time required by a competent worker or unattended machine to perform a task, aligning production with client demand.
• Work Station: The physical area where specific tasks are performed by workers or machines in a production line.
• Downtime: Non-value-added time, associated with the seven wastes including defects, overproduction, waiting, transportation, unnecessary inventory, unnecessary motion, and inappropriate processing.

Steps in Solving Line Balancing

There are four steps in solving line balancing described by G. Andrew (2006).

• Drawing Precedence Diagram: A precedence diagram is crafted to illustrate the relationship between workstations. Each process commences upon completion of the preceding one.
• Determining Cycle Time: Cycle time denotes the maximum time allotted at each station, calculated using the formula:

This means the products needs to leave the workstations before it reaches its cycle time.

• Assigning Tasks to Workstations: Task allocation is performed after completing a time cycle. Tasks should ideally be assigned to workstations in order of longest task times.

• Calculating Line Efficiency: This is done to find effectiveness of the line. The formula is given by:

Computerized Line Balancing

As manual line balancing becomes cumbersome with increasing problem complexity, software packages offer rapid balancing solutions. These packages employ various heuristics to balance the line efficiently. Two common line balancing heuristics are:

• Incremental Utilization Heuristic: Tasks are added to each workstation one at a time in order of task precedence until utilization reaches 100%.
• Longest Task Time Heuristic: Tasks are added to workstations one at a time based on task precedence. If multiple tasks are available, the longest task is added, applicable when each task's time is less than or equal to the cycle time, and there are no duplicate workstations.

Conclusion

Line balancing entails adjusting the capacity of a production line to accommodate a specific model mix. The line's capacity is determined by the number of tasks and individual capacities in line segments, while the model mix is influenced by materials, their rates, and routing. Line balancing is described as the equal distribution of workload across all operations to eliminate bottlenecks and excess capacity.