CNC Machining worked example

CNC Program Runtime with in-cut cutting time of 3.75 min: a worked example

This worked example runs the cnc program runtime numbers for a tougher week than the baseline: in-cut cutting time of 3.75 min instead of the typical 7.5 min. Estimate total CNC program runtime by summing cutting time, rapid/non-cutting time, tool-change/probing time, and load or unload allowance.

The inputs for this scenario

  • In-cut cutting time: 3.75 min (the input this scenario stresses; the baseline uses 7.5)
  • Rapid, approach, and air-cut time: 1.8 min (held at the documented default)
  • Tool-change, probing, and in-process inspection time: 1.2 min (held at the documented default)
  • Load, unload, and operator handling allowance: 2 min (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: CNC program runtime = cutting time + rapid, approach, and non-cutting time + tool change, probing, and inspection time + load, unload, and operator allowance.
  • estimated CNC program runtime works out to 8.75 min at these inputs, and this is the headline figure for the scenario.
  • Element 1 works out to 3.75 min at these inputs.
  • Element 2 works out to 1.8 min at these inputs.
  • Element 3 + 4 works out to 3.2 min at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where in-cut cutting time sits at 7.5 min and the headline result is 12.5 min, this scenario comes in 30% below the baseline at 8.75 min.
  • Use it when quoting a new part, building a routing, or sanity-checking estimated cycle time against machine history. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • estimated CNC program runtime: 8.75 min (headline result)
  • Element 1: 3.75 min
  • Element 2: 1.8 min
  • Element 3 + 4: 3.2 min

Run it with your numbers

  • To rerun this with your own numbers, open the live CNC Program Runtime calculator, set in-cut cutting time to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.