GlossaryKind of term: Manufacturing termCycle time
What is cycle time?
Cycle time is the time a machine needs per part in one setup; what it includes, such as loading and unloading, depends on the convention used.
Cycle time is the time one part takes on the machine in one setup. What it includes is not uniform. The cycle timer on the control usually runs from cycle start to program end: cutting, rapids, tool changes and probing. In estimating and production planning, cycle time often also includes loading, clamping and unloading, part to part. A part in two setups usually has two cycle times, unless both setups run in one cycle, side by side on the table for example. Before production, cycle time is an estimate; afterwards, a measurement.
What does cycle time depend on?
Cycle time consists of cutting time, when the tool removes material, and non-cutting time: rapids, tool changes, probing, loading and unloading. Cutting time depends on material, cutting data, tooling, the volume to remove and the stiffness of part and setup. Non-cutting time depends on the machine, the number of tools and how the machine is loaded. With a pallet changer or robot, loading and unloading largely happen while the machine cuts; with several parts per setup, cycle time per part is the time per setup divided by the number of parts in it.
How does cycle time work in practice?
Cycle time times machine hour rate gives machining cost per part, and on batches that is often the largest item. An error in the estimated cycle time multiplies with quantity: on a large batch a small error weighs heavily. Counting only cutting time and leaving out tool changes, rapids and loading makes estimates systematically low. A measured cycle time belongs to one machine, one program and one setup; compare an estimate only with a measurement made under the same convention.
What is cycle time often confused with?
Cycle time is not lead time: cycle time is minutes per part on a machine, lead time is days or weeks from order to delivery, mostly waiting. Nor is it setup time: setup returns per batch, cycle time per part. And an estimated cycle time is not an actual cycle time: one is calculated, the other measured.
How do you see cycle time in Blake?
In Blake the machining line carries a time, a rate and a quantity, and the result is labelled as an estimate. With a better figure to hand, you correct the time with a reason; the previous value is kept. More on estimating.
Frequently asked questions
Does cycle time include loading and unloading?
It depends on the convention. The control's timer usually measures program run time only. In an estimate, loading and unloading have to count somewhere: in the cycle time or as separate non-cutting time.
Is setup time included in cycle time?
No. Setup falls once per setup and per batch, cycle time per part. In the estimate you spread setup time over the quantity and count cycle time per part.
How reliable is an estimated cycle time?
That depends on how firmly route, tooling and cutting data are settled and whether similar parts have been made. A CAM time or a measurement on the machine is more reliable; compare them only under the same convention.