Gaskets, Seals, O-Rings & Elastomer Components worked example

Material Shrinkage with cured part dimension of 25 mm: a worked example in gaskets, seals, o-rings & elastomer components

Here is what the math looks like when conditions slip. We hold every other input steady and drop cured part dimension to 25 mm, then walk the calculation through step by step. Estimate elastomer material shrinkage by comparing the mold or tooling dimension with the cured part dimension.

The inputs for this scenario

  • Cured part dimension: 25 mm (the input this scenario stresses; the baseline uses 49.25)
  • Mold or tool dimension: 50 mm (held at the documented default)
  • Shrinkage reference dimension: 50 mm (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Material shrinkage = (mold or tool dimension - cured part dimension) ÷ shrinkage reference dimension × 100.
  • Material shrinkage works out to 50 % at these inputs, and this is the headline figure for the scenario.
  • Dimension change from tool to cured part works out to 25 value at these inputs.
  • Minimum works out to 25 value at these inputs.
  • Maximum works out to 50 value at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where cured part dimension sits at 49.25 mm and the headline result is 1.5 %, this scenario comes in 3,233% above the baseline at 50 %.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to cured part dimension, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. Shrinkage varies with compound, durometer, cure state, part geometry, and post-cure; a single linear figure will not perfectly predict shrinkage across all features or directions.

Results at a glance

  • Material shrinkage: 50 % (headline result)
  • Dimension change from tool to cured part: 25 value
  • Minimum: 25 value
  • Maximum: 50 value

Run it with your numbers

  • To rerun this with your own numbers, open the live Material Shrinkage calculator, set cured part dimension to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.