Municipal Waste Sorting Equipment worked example

Spare Parts Buffer with wear-part daily consumption rate of 1 units / day: a worked example in municipal waste sorting equipment

This worked example runs the spare parts buffer numbers for a tougher week than the baseline: wear-part daily consumption rate of 1 units / day instead of the typical 2 units / day. Estimate the spare parts buffer for MRF critical items (belts, rotors, valves, sensors) using daily usage, lead time, and a safety stock.

The inputs for this scenario

  • Wear-part daily consumption rate: 1 units / day (the input this scenario stresses; the baseline uses 2)
  • Supplier or rebuild lead time: 14 days (held at the documented default)
  • Safety stock buffer: 6 units (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Cycle stock = daily consumption rate x supplier or rebuild lead time.
  • Protected days of supply works out to 0.01 units at these inputs, and this is the headline figure for the scenario.
  • Unprotected days works out to 0.07 days at these inputs.
  • Inventory works out to 1 pieces at these inputs.
  • Daily usage works out to 14 pieces / day at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where wear-part daily consumption rate sits at 2 units / day and the headline result is 0.02 units, this scenario comes in 50% below the baseline at 0.01 units.
  • Use it when setting reorder points and min/max levels for fast-moving wear parts like screen discs, belt cleats, conveyor rollers, and optical-sorter nozzles. 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

  • Protected days of supply: 0.01 units (headline result)
  • Unprotected days: 0.07 days
  • Inventory: 1 pieces
  • Daily usage: 14 pieces / day

Run it with your numbers

  • To rerun this with your own numbers, open the live Spare Parts Buffer calculator, set wear-part daily consumption rate to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.