Glass Container & Bottle Manufacturing worked example

Mold Changeover Time at 23% changeover contingency allowance: a worked example

What does the result look like when changeover contingency allowance reaches 23%? The full calculation is worked below with real intermediate numbers. Use it when scheduling blank molds, blow molds, neck rings, guide rings, funnels, baffles, take-outs, dead plates, and job-change labor across IS machine sections.

The inputs for this scenario

  • Mold sets to change: 12 mold sets (unchanged)
  • Mold change crew rate: 4 mold sets / hr (unchanged)
  • Changeover contingency allowance: 23 % (raised for this scenario; the documented default is 20)

Working through the calculation

  • Applying the documented formula (Base mold changeover time = mold equipment change workload รท measured mold change rate) to the inputs above produces each figure below.
  • At this operating point the engine returns 3.69 hr for required mold changeover time, the number this scenario is built around.
  • At this operating point the engine returns 3 hr for base mold changeover time.
  • At this operating point the engine returns 23 % for changeover allowance applied.
  • At this operating point the engine returns 4 pieces / min for measured mold change rate.

How this compares with the baseline

  • Against the tool's baseline example, where changeover contingency allowance sits at 20% and the headline result is 3.6 hr, this scenario comes in 2.5% above the baseline at 3.69 hr.
  • A figure at this level is achievable when changeover contingency allowance is genuinely sustained, not just peaked for a shift. It assumes a steady crew rate and a single allowance figure; a complex change involving forehearth color conditioning or major section rebuilds can blow past the allowance and needs separate ramp-up planning.

Results at a glance

  • Required mold changeover time: 3.69 hr (headline result)
  • Base mold changeover time: 3 hr
  • Changeover allowance applied: 23 %
  • Measured mold change rate: 4 pieces / min

Run it with your numbers

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

Last reviewed 2026-05-12.