Injection Molding worked example

Barrel Residence Time with barrel melt capacity of 630 g: a worked example

What does the result look like when barrel melt capacity reaches 630 g? The full calculation is worked below with real intermediate numbers. Use this to verify that residence time stays within the resin thermal stability window. Excessive barrel time causes degradation, discoloration, and reduced properties in heat-sensitive resins like PVC, POM, and PET.

The inputs for this scenario

  • Barrel melt capacity: 630 g (raised for this scenario; the documented default is 250)
  • Actual shot weight per cycle: 55 g (unchanged)

Working through the calculation

  • Applying the documented formula (Barrel shots = Barrel capacity / Shot weight) to the inputs above produces each figure below.
  • At this operating point the engine returns 11.45 min for ratio, the number this scenario is built around.
  • At this operating point the engine returns 11.45 value for raw ratio.
  • At this operating point the engine returns 1 x for conversion factor.
  • At this operating point the engine returns 55 value for denominator.

How this compares with the baseline

  • Against the tool's baseline example, where barrel melt capacity sits at 250 g and the headline result is 4.55 min, this scenario comes in 152% above the baseline at 11.45 min.
  • A figure at this level is achievable when barrel melt capacity is genuinely sustained, not just peaked for a shift. It assumes a fully purged, well-mixed barrel and uses nominal barrel capacity; real screws have dead spots and stagnation zones where material lingers far longer than the average suggests.

Results at a glance

  • Ratio: 11.45 min (headline result)
  • Raw ratio: 11.45 value
  • Conversion factor: 1 x
  • Denominator: 55 value

Run it with your numbers

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

Last reviewed 2026-05-12.