CNC Machining worked example

Drilling Cycle Time at 29% peck, retract, and chip-clearance allowance: a worked example

What does the result look like when peck, retract, and chip-clearance allowance reaches 29%? The full calculation is worked below with real intermediate numbers. estimating drilling cycle time for quoting, routing, capacity planning, or comparing alternate CNC programs

The inputs for this scenario

  • total drilled depth: 48 in (unchanged)
  • drilling feed rate: 16 in / min (unchanged)
  • peck, retract, and chip-clearance allowance: 29 % (raised for this scenario; the documented default is 25)

Working through the calculation

  • Applying the documented formula (Base drilling cycle time = total drilled depth รท drilling feed rate) to the inputs above produces each figure below.
  • At this operating point the engine returns 3.87 min for estimated drilling cycle time, the number this scenario is built around.
  • At this operating point the engine returns 3 min for base drilling cycle time.
  • At this operating point the engine returns 29 % for peck, retract, and chip-clearance allowance.
  • At this operating point the engine returns 16 pieces / min for drilling feed rate.

How this compares with the baseline

  • Against the tool's baseline example, where peck, retract, and chip-clearance allowance sits at 25% and the headline result is 3.75 min, this scenario comes in 3.2% above the baseline at 3.87 min.
  • A figure at this level is achievable when peck, retract, and chip-clearance allowance is genuinely sustained, not just peaked for a shift. It treats peck and chip-clearance time as a flat allowance, so it can misjudge very deep holes where retract count and dwell dominate and the real overhead is nonlinear.

Results at a glance

  • estimated drilling cycle time: 3.87 min (headline result)
  • base drilling cycle time: 3 min
  • peck, retract, and chip-clearance allowance: 29 %
  • drilling feed rate: 16 pieces / min

Run it with your numbers

  • Every input above is editable in the live Drilling Cycle Time calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.