BIZOMAT Tools · Operations
Bottleneck and Line Balance
Which step is constraining the process?
Identifies the constraint step in a three-step flow, compares it with takt time and shows line balance efficiency.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Available production time | min/day | Net available production minutes per day |
| Daily demand | units | Units required per day |
| Step A cycle time | min | Observed cycle time of step A (0 if not used) |
| Step B cycle time | min | Observed cycle time of step B (0 if not used) |
| Step C cycle time | min | Observed cycle time of step C (0 if not used) |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Available production time
- What it is
- The net minutes per day the line can run after breaks, meetings and planned stops, shared by all three steps.
- Units and format
- Enter a number in min/day: min/day. The form accepts 1 min/day or more.
- Example
- The form opens with 420 min/day as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- More time lengthens takt and raises daily line capacity.
- Get it right
- Use net time, not paid shift time: an 8-hour shift with 60 minutes of breaks gives 420 minutes.
What this means: Daily demand
- What it is
- The number of units the customer needs from the line each day, used to set the takt time.
- Units and format
- Enter a number in units: a count of units. The form accepts 1 units or more.
- Example
- The form opens with 120 units as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Higher demand shortens takt, so steps are more likely to be over takt.
- Get it right
- Use average daily demand over the planning period, not a single peak day.
What this means: Step A cycle time
- What it is
- The observed time step A takes to complete one unit, timed at the workstation over several cycles.
- Units and format
- Enter a number in min: minutes. The form accepts 0 min or more.
- Example
- The form opens with 2.5 min as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- If it is the longest cycle, it sets line capacity and the constraint load.
- Get it right
- Enter 0 to leave the step out. Use a representative time, not the best cycle seen.
What this means: Step B cycle time
- What it is
- The observed time step B takes to complete one unit, timed at the workstation over several cycles.
- Units and format
- Enter a number in min: minutes. The form accepts 0 min or more.
- Example
- The form opens with 3.8 min as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- If it is the longest cycle, it sets line capacity and the constraint load.
- Get it right
- Enter 0 to leave the step out. Use a representative time, not the best cycle seen.
What this means: Step C cycle time
- What it is
- The observed time step C takes to complete one unit, timed at the workstation over several cycles.
- Units and format
- Enter a number in min: minutes. The form accepts 0 min or more.
- Example
- The form opens with 2.9 min as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- If it is the longest cycle, it sets line capacity and the constraint load.
- Get it right
- Enter 0 to leave the step out. Use a representative time, not the best cycle seen.
Method and formulas
- Takt = available minutes ÷ demand
- Constraint = step with the longest cycle time
- Line capacity = available minutes ÷ constraint cycle
- Balance efficiency = sum of cycles ÷ (steps × constraint cycle)
Limitations
- Three steps, one product, no buffers or downtime
- Uses average cycle times
Typical uses
- Finding where to improve first
- Balancing work between stations
Who it is for
- Production engineers
- Lean practitioners
- Supervisors
What you get
- The constraint step and whether it meets takt
- Line capacity and balance efficiency
- Step loading table
Interpreting the result
- Improving a non-constraint step does not raise output
- Low balance efficiency means idle time at faster steps
References
- Goldratt E. M. and Cox J., The Goal (North River Press)
- Rother M. and Shook J., Learning to See (Lean Enterprise Institute)
Learn the Concepts Behind This Tool
These BIZOMAT Library readings explain the method this tool uses, with worked examples.
Method explained here · BIZOMAT original book
Balancing an assembly line
In Shop Floor Optimisation by the Numbers
What it covers: Balance an assembly line to takt: takt time, the least number of stations, precedence, the positional weight rule, exhaustive checks, and the BIZOMAT takt, bottleneck and cycle time tools.
BIZOMAT tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.