CNC Machining worked example

Lights-Out Machining Capacity at 59% unattended uptime expectation: a worked example

This worked example runs the lights-out machining capacity numbers for a tougher week than the baseline: 59% unattended uptime expectation instead of the typical 82%. Estimate unattended CNC output from pallet capacity, unattended cycles, uptime, and expected first-pass yield.

The inputs for this scenario

  • Unattended parts produced per cycle: 6 parts / cycle (held at the documented default)
  • Lights-out cycles available overnight: 72 cycles (held at the documented default)
  • Unattended uptime expectation: 59 % (the input this scenario stresses; the baseline uses 82)
  • Lights-out first-pass yield: 96 % (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Gross lights-out machining capacity = unattended parts per cycle × lights-out cycles available.
  • good lights-out machining capacity works out to 245 parts at these inputs, and this is the headline figure for the scenario.
  • gross lights-out machining capacity works out to 432 parts at these inputs.
  • Lights-Out Machining Capacity loss from downtime works out to 177 parts at these inputs.
  • Lights-Out Machining Capacity loss from scrap or rework works out to 10.2 parts at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where unattended uptime expectation sits at 82% and the headline result is 340 parts, this scenario comes in 28.05% below the baseline at 245 parts.
  • Use it when planning overnight or weekend unattended runs and committing how many good parts will be waiting at the start of the next shift. 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

  • good lights-out machining capacity: 245 parts (headline result)
  • gross lights-out machining capacity: 432 parts
  • Lights-Out Machining Capacity loss from downtime: 177 parts
  • Lights-Out Machining Capacity loss from scrap or rework: 10.2 parts

Run it with your numbers

  • To rerun this with your own numbers, open the live Lights-Out Machining Capacity calculator, set unattended uptime expectation to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.