CNC Machining worked example
Tool Life with average tool usage of 30 tools / day: a worked example
This scenario runs the tool life calculation on the strong side: average tool usage of 30 tools / day, with every other input held at its documented default. planning tool crib stocking, tool-change intervals, or replacement coverage for a CNC production job
The inputs for this scenario
- Average tool usage: 30 tools / day (raised for this scenario; the documented default is 12)
- Tool replenishment lead time: 10 days (unchanged)
- Tool-life safety stock: 25 tools (unchanged)
Working through the calculation
- Applying the documented formula (Lead-time tool demand = average tool usage × tool replenishment lead time) to the inputs above produces each figure below.
- At this operating point the engine returns 325 tools for required cutting-tool stock, the number this scenario is built around.
- At this operating point the engine returns 300 tools for lead-time tool demand.
- At this operating point the engine returns 25 tools for tool-life safety stock.
- At this operating point the engine returns 10.83 days for tool coverage days.
How this compares with the baseline
- Against the tool's baseline example, where average tool usage sits at 12 tools / day and the headline result is 145 tools, this scenario comes in 124% above the baseline at 325 tools.
- Use it when setting reorder points for the tool crib, onboarding a new tool with an unfamiliar supplier lead time, or reviewing stockouts that idled a machine. Treat this as a target state: the delta against the baseline quantifies what the improvement is worth before you commit to chasing it.
Results at a glance
- Required cutting-tool stock: 325 tools (headline result)
- Lead-time tool demand: 300 tools
- Tool-life safety stock: 25 tools
- Tool coverage days: 10.83 days
Run it with your numbers
- Every input above is editable in the live Tool Life calculator, which recalculates instantly and can be shared with the inputs intact.
Last reviewed 2026-05-12.