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Cycle Time

Cycle time is what the equipment actually achieves: the elapsed time from the start of one operation to the start of the next identical one. It is a measured capability, not a target.

A line has as many cycle times as it has stations, and only one of them matters for capacity: the longest. That station is the bottleneck, and the line runs at its pace no matter how fast everything upstream and downstream is. Balancing a line means moving work between stations until no single one dominates, which is where most of the engineering effort in a line quote goes.

Cycle time is usually quoted as a nominal figure and lived as something worse. Nominal cycle assumes the part is present, the tool is sharp and nothing has jammed. Effective cycle includes the stoppages. The gap between them is why a line rated at 55 JPH averages 47 in the plant, and why the contract rate and the design rate are never the same number.

For quoting purposes the useful question is not what cycle time the line achieves but what cycle time the customer's takt requires, and how much headroom sits between the two. Headroom is margin against penalty. Too little and you carry risk you did not price; too much and you have quoted more equipment than the job needs and lost the bid.

What gets counted, and what gets missed

  • Counted: robot motion, clamp and unclamp, weld or process time, part transfer between stations.
  • Often missed: tool change frequency, dress cycles on welding tips, part presence checks that fail and retry.
  • Almost always missed: rework loops, operator intervention on a manual station, shift changeover.
  • Measured how: start of an operation to start of the next identical operation, not start to finish of one part.

Related

Takt Time JPH (Jobs Per Hour) OEE Production-Line Quoting

Frequently Asked Questions

What is the difference between cycle time and lead time?
Cycle time is the pace of one repeated operation, measured in seconds on a line. Lead time is how long a whole order takes from receipt to delivery, measured in days or weeks. They are unrelated measures that get confused because both sound like speed.
Which station's cycle time sets the line rate?
The slowest one. A line runs at the pace of its bottleneck, so a single station 8 seconds over the others costs the whole line 8 seconds per unit regardless of how quickly the rest run.
How is cycle time measured properly?
From the start of one operation to the start of the next identical operation, not from the start to the finish of a single part. Measuring start to finish undercounts, because it ignores the time the station spends waiting to begin again.

Cycle balance and bottleneck stations, surfaced at quote time.

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