Blow Molding & Hollow Plastic Products worked example

Neck Finish Tolerance Margin with allowable neck finish tolerance of 0.5 mm or in: a worked example

This scenario runs the neck finish tolerance margin calculation on the strong side: allowable neck finish tolerance of 0.5 mm or in, with every other input held at its documented default. a quality or process engineer needs to check neck finish margin before releasing bottles or adjusting setup

The inputs for this scenario

  • Allowable neck finish tolerance: 0.5 mm or in (raised for this scenario; the documented default is 0.2)
  • Measured neck finish deviation: 0.13 mm or in (unchanged)
  • Reference neck tolerance: 0.2 mm or in (unchanged)

Working through the calculation

  • Applying the documented formula (Remaining neck finish tolerance = allowable neck finish tolerance - measured neck finish deviation) to the inputs above produces each figure below.
  • At this operating point the engine returns 185 % tolerance margin for neck finish tolerance margin, the number this scenario is built around.
  • At this operating point the engine returns 0.37 mm or in for remaining neck finish tolerance.
  • At this operating point the engine returns 0.5 mm or in for allowable neck finish tolerance.
  • At this operating point the engine returns 0.13 mm or in for measured neck finish deviation.

How this compares with the baseline

  • Against the tool's baseline example, where allowable neck finish tolerance sits at 0.2 mm or in and the headline result is 35 % tolerance margin, this scenario comes in 429% above the baseline at 185 % tolerance margin.
  • Use it during process qualification and routine SPC checks to judge how much dimensional buffer the neck finish still has. Treat this as a target state: the delta against the baseline quantifies what the improvement is worth before you commit to chasing it.

Results at a glance

  • Neck finish tolerance margin: 185 % tolerance margin (headline result)
  • Remaining neck finish tolerance: 0.37 mm or in
  • Allowable neck finish tolerance: 0.5 mm or in
  • Measured neck finish deviation: 0.13 mm or in

Run it with your numbers

  • Every input above is editable in the live Neck Finish Tolerance Margin calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.