GlossaryKind of term: Manufacturing termActual cycle time
What is actual cycle time?
Actual cycle time is the time per part measured on the machine during production, as opposed to the estimated or calculated cycle time.
A measured value belongs to one operation on one machine. What it contains depends on the agreed start and end points. Program run time runs from cycle start to program end. Floor-to-floor time also counts loading, unloading and checks at the machine. An average over the batch, run time divided by the number of good parts, includes interruptions as well. When several parts are machined per cycle, divide by that number.
What does actual cycle time depend on?
A measured time differs from a calculated one for several reasons. A time from CAM or from the header of an NC program is a calculation: axis acceleration and deceleration, a control that cannot reach the programmed feed on short segments, the real tool or pallet change time, probing and interruptions are often missing from it in whole or in part. At the machine, the operator's override, adjusted cutting data, chip problems and wear add to that. The source decides how firm the figure is: start and stop from the control or the MES are measured, a time written on a job card afterwards is a declaration.
How does actual cycle time work in practice?
A measured time can only be compared with the estimate when it covers the same scope: the same operation, machine and setup, and the same choice on whether loading and unloading count. A single part tells you little; the spread across a batch, and preferably several batches, shows whether a difference is structural. If the actual time keeps sitting above the estimate, the estimate for later orders of that part carries too little time until you adjust it; if it sits below, it carries too much. What that means for the price depends on batch size, hourly rate and how you set the price.
What is actual cycle time often confused with?
Actual cycle time is not the calculated cycle time from CAM or the estimate: that is a prediction, this is a measurement. Nor is it cutting time: cutting time covers only the time the tool is in the cut, cycle time also holds non-cutting time such as tool changes and rapid moves. And it is not lead time, which often consists mostly of waiting, transport and subcontracting.
Frequently asked questions
Where do I get the actual cycle time from?
From the control or the MES, if they record when the program starts and stops, or from the job card on which time is booked per operation. Note the machine, the setup and what the time covers; without those it cannot be compared later.
Can I adjust the estimate on one measured time?
Better not. One reading can include a first-off, a tool breakage or an interruption. Compare several parts from the same batch, and preferably several batches, before you change the standard for that operation.
Why does a part take longer on the machine than CAM calculates?
Often because the calculation assumes the programmed feed without full axis dynamics, and leaves out tool changes, probing and override in whole or in part. How large the gap is depends on the machine, the program and the calculation method.