Blow Molding & Hollow Plastic Products worked example

Neck Finish Tolerance Margin with allowable neck finish tolerance of 0.1 mm or in: a worked example

This worked example runs the neck finish tolerance margin numbers for a tougher week than the baseline: allowable neck finish tolerance of 0.1 mm or in instead of the typical 0.2 mm or in. Calculate dimensional margin between available neck finish tolerance and measured neck finish requirement for blow molded bottles or containers.

The inputs for this scenario

  • Allowable neck finish tolerance: 0.1 mm or in (the input this scenario stresses; the baseline uses 0.2)
  • Measured neck finish deviation: 0.13 mm or in (held at the documented default)
  • Reference neck tolerance: 0.2 mm or in (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Remaining neck finish tolerance = allowable neck finish tolerance - measured neck finish deviation.
  • Neck finish tolerance margin works out to -15 % tolerance margin at these inputs, and this is the headline figure for the scenario.
  • Remaining neck finish tolerance works out to -0.03 mm or in at these inputs.
  • Allowable neck finish tolerance works out to 0.1 mm or in at these inputs.
  • Measured neck finish deviation works out to 0.13 mm or in at these inputs.

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 143% below the baseline at -15 % tolerance margin.
  • Use it during process qualification and routine SPC checks to judge how much dimensional buffer the neck finish still has. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Neck finish tolerance margin: -15 % tolerance margin (headline result)
  • Remaining neck finish tolerance: -0.03 mm or in
  • Allowable neck finish tolerance: 0.1 mm or in
  • Measured neck finish deviation: 0.13 mm or in

Run it with your numbers

  • To rerun this with your own numbers, open the live Neck Finish Tolerance Margin calculator, set allowable neck finish tolerance to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.