Injection Molding worked example

Injection Molding Cycle Time at 14% non-productive time allowance: a worked example

What does the result look like when non-productive time allowance reaches 14%? The full calculation is worked below with real intermediate numbers. Use this when quoting a new mold, validating a cycle target, or comparing press utilization across different part programs.

The inputs for this scenario

  • Total shots required: 500 shots (unchanged)
  • Press cycling rate: 3 shots / min (unchanged)
  • Non-productive time allowance: 14 % (raised for this scenario; the documented default is 12)

Working through the calculation

  • Applying the documented formula (Base run time = Total shots required / Press cycling rate) to the inputs above produces each figure below.
  • At this operating point the engine returns 190 sec for total molding run time (with allowance), the number this scenario is built around.
  • At this operating point the engine returns 167 sec for net press run time.
  • At this operating point the engine returns 14 % for non-productive time added.
  • At this operating point the engine returns 3 pieces / min for press cycling rate used.

How this compares with the baseline

  • Against the tool's baseline example, where non-productive time allowance sits at 12% and the headline result is 187 sec, this scenario comes in 1.79% above the baseline at 190 sec.
  • A figure at this level is achievable when non-productive time allowance is genuinely sustained, not just peaked for a shift. It treats the press cycling rate as constant; cooling-dominated thick parts, mold temperature drift, or material changeovers can shift the real rate during the run.

Results at a glance

  • Total molding run time (with allowance): 190 sec (headline result)
  • Net press run time: 167 sec
  • Non-productive time added: 14 %
  • Press cycling rate used: 3 pieces / min

Run it with your numbers

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

Last reviewed 2026-05-12.