With our work with some of the biggest names in manufacturing, (we name-drop here), line balancing is a very common need we come across.
This is a key concept in both lean manufacturing and value stream mapping (VSM). Line balancing means you allocate work as evenly as possible, across all processes or workstations within a production line. Your main goal with line balancing is to make sure that each workstation has a similar cycle time, which then means less idle time and reduces bottlenecks. Proper line balancing will help you maximize efficiency and productivity, reduce labor costs, and improve overall workflow.
The Importance of Line Balancing in Lean Manufacturing
With line balancing, you’re trying to eliminate the eight types of waste in lean (e.g., waiting, overproduction, excess motion) by aligning production flow to the takt time. Takt time is the rate at which finished products need to be produced, to meet customer demand.
By distributing work evenly, line balancing reduces bottlenecks and idle time, and makes sure that resources and time are used effectively, making the whole system more efficient.
When the line is balanced, work-in-progress (WIP) inventory between stations is minimized, leading to a smoother flow and less need for storage because of the reduced inventory.
And a balanced line creates a more predictable production environment, which helps in maintaining consistent quality levels and smooth workflows.
Role of Line Balancing in Value Stream Mapping (VSM)
In VSM, line balancing is visually represented and analyzed through tools like takt time calculations, process cycle times, and resource allocation. VSM helps identify imbalances and areas of waste, providing a roadmap for achieving a balanced line.
During the current state VSM analysis, line balancing issues are highlighted by measuring the time and resource usage of each process step. You also measure cycle times, and identify areas of over- or under-utilization.
VSM then helps to pinpoint where bottlenecks are happening. It’s often at points where line balancing is not optimal, and these bottlenecks cause delays, increased WIP, and higher costs.
And of course, part of value stream mapping is designing a future state. In the future state map, line balancing improvements are proposed to optimize the flow and create a more synchronized production line. This involves realigning process steps, redistributing labor, and adjusting workloads to make sure that all processes can meet the takt time.
Line Balancing: Techniques to Achieve a Balanced Line
Break down tasks to understand their duration, difficulty, and requirements. Group tasks into similar cycle times to create balanced workloads.
Calculate takt time, which is used as a reference point for balancing the line. The formula is: Takt Time = Available Production Time / Customer Demand
Every workstation’s cycle time should be adjusted to meet or stay under the takt time.
Then, rearrange or combine tasks and workstations to improve flow. This might involve changing the sequence of operations, standardizing work, or developing flexible workstations.
If you've ever noticed U-shaped production cells in a factory, it's because these cells often improve line balancing by minimizing travel time and improving communication among workers.
Common Challenges When Balancing Lines in Lean Manufacturing
Handling a wide variety of products or complex assemblies can complicate line balancing. Each product may require different cycle times or equipment, making it harder to standardize workloads. eVSM software has been developed to handle this high product variety.
Fluctuations in customer demand can disrupt a balanced line, as stations may become overloaded or underutilized depending on volume changes.
And even the operators’ skills and efficiency can lead to imbalances in the line. Cross-training can help mitigate this issue; you need to make sure that workers can perform multiple tasks as needed.
Which metrics should you track for line balancing?
Cycle Time vs. Takt Time
A key metric to determine whether workstations are balanced. Any deviation from takt time can indicate potential areas for improvement.
Work-in-Progress (WIP) Inventory Levels
Higher WIP levels between stations usually signify imbalances in the line.
Production Lead Time
Total lead time can increase if there is a lack of workstations are not coordinated properly.
Efficiency or Utilization Rates
This measures how effectively resources are being used. A high utilization rate may point to a line being a bottleneck; on the other hand, if it is too low, there may be resources that are not being used as much as they could be.
Tools and Software for Line Balancing
Software solutions, like digital value stream mapping tools, can help visualize and analyze line balancing data. eVSM software provides real-time insights and simulations, making it easier to see the impact of changes and optimize line balancing strategies.
This can be your secret sauce to getting your operations running effectively. Take a look at some of the companies that use eVSM in their operations. And the best part? Because we work so closely with you on creating your first value stream map, you’ll probably ROI while you’re still on your free trial. Book a meeting today!