What is a Bottleneck (or Constraint) in Manufacturing?
In operations, “bottleneck” refers to a work stage that cannot meet the production quota even at its maximum throughput capacity, thereby delaying or stopping the flow of operations.
This concept equally applies to management and logistics. Here bottlenecks can restrict the flow of information, guidance, and work instructions.
A bottleneck in production works the same as a physical bottle. The narrow neck reduces the rate at which water flows out, and causes backup behind it.
In an operation, bottlenecks can cause major interruptions to work productivity, delaying the production process across the board, and failing to keep up with the rate of customer demand.
Short-term vs Long-term Bottlenecks
- Short-term Bottleneck: These are caused by temporary problems. An operator absence or a delay in receiving materials from another vendor due to one-off shipping problems are types of short-term bottlenecks.
- Long-term Bottleneck: These are caused by recurring issues that have substantial impacts on the overall manufacturing processes. Some examples include:
- Delayed production time due to paper-based work instructions and audit procedures
- Lack of traceability due to a disorganized material tracking system
- No real-time data available to identify patterns in production
Since short-term bottlenecks are isolated incidences that do not need regular attention or remedies, long-term bottlenecks are the ones that need solutions for their root causes.
Goals of the Bottleneck Analysis
- Identify the key bottlenecks in production and managerial processes
- Collect relevant quantitative data for bottleneck analysis
- Explore possible solutions to address the bottlenecks
- Minimize poor-quality products, increase worker efficiency, reduce downtime
- Increase the overall production capacity and shorten lead time
What to look for in a Bottleneck Analysis
Most likely, the machine or the process that has the longest queue will be the bottleneck. To identify whether a target step is the root barrier to the overall workflow, you can look for these red flags in the production process to make an accurate assessment.
Throughput and Throughput Time
Increasing the throughput of each machine one at a time will reveal which has the greatest effect on the overall production output. Longer than average throughput time will also mean a possible delay in the process, inspection, and move time, as well as an increase in the wait time. This may require further investigation to identify which step of the throughput time is taking unnecessarily long.
Whenever the input is greater than what a machine can handle, an accumulation will occur following that step. Inventory and work hours can accumulate because the work order cannot be processed at the same rate as the other steps in the manufacturing process.
A unit or a machine that uses the highest percentage of its full capacity will likely be the bottleneck of the production process. This can be easily compared to the lower capacity utilization rate of the other units on the shop floor. If the input was to increase for the bottleneck unit, it will most likely cap out first.
Are there errors resulting from miscommunication or slow communication that may lead to slowdowns in the manufacturing process? Faulty communication at all operational levels can translate into low physical productivity.
Bottleneck Analysis Tools
The 5 Whys
A part of Root Cause Analysis, the 5 Whys can identify contributing events that lead to bottlenecks in production. This method backtracks from the problem to its source by continuously asking ‘Why’ to its previous answer. You can read more about the 5 Whys in the article here.
Fishbone Diagram (or Ishikawa)
The Fishbone Diagram is the visual method of root cause analysis. The problem is written on the fish’s head, with the causes of that problem listed under major causes that branch off into the shape of fishbones. Learn more about the diagram and how Tulip can help you standardize Fishbone Diagram methodologies throughout your factory!