Answer

How do you plan capacity with simulation?

Model the plant as it runs today — stations, cycle times, shifts, breakdowns, changeovers — run it over a planning horizon and keep that run as the baseline. Then change one thing, such as a shift, a changeover time or a machine, and run it again: the difference in output, utilisation and lead time is the capacity the change would buy.

Simulation adds what an average in a spreadsheet hides: the breakdowns, changeovers and variability that make a line deliver less than its rated rate.

Reviewed 5 October 2026

How Optonum does it

  • A fixed-time-step flow simulation that runs in the browser, with nothing to install.
  • Breakdowns drawn from MTBF (Weibull) and repairs from MTTR, a shared maintenance crew, operator fatigue, sequence-dependent changeovers, scrap and rework, and demand variability.
  • The run follows the plant's own shift calendar, and its warm-up period is found automatically.
  • Each project keeps a baseline run, and a scenario is compared with it side by side.
  • When the Bottleneck Oracle tests a remedy, it repeats the run to give a spread rather than one lucky answer.

What it does not do

  • It is a flow model: queues exist only where a buffer is drawn, and lead time and work in process are calculated by formula.
  • A run you start yourself is one run; its spread is the variation within that run, not a confidence interval.
  • A simulated figure is an estimate from the data you entered, not a measurement of your plant.
How do you plan capacity with simulation? — Optonum