Injection Molding worked example

Defect Rate by Cavity with rejected parts from this cavity of 30 parts: a worked example

Push rejected parts from this cavity up to 30 parts and the picture changes. This example computes every intermediate figure at that operating point. Use this to compare reject rates across cavities, identify cavities needing maintenance, or track quality improvement after mold repairs or process adjustments.

The inputs for this scenario

  • Rejected parts from this cavity: 30 parts (raised for this scenario; the documented default is 12)
  • Total parts produced from this cavity: 500 parts (unchanged)

Working through the calculation

  • Applying the documented formula (Cavity defect rate = (Rejected parts / Total parts from cavity) x 100) to the inputs above produces each figure below.
  • At this operating point the engine returns 6 % for rate, the number this scenario is built around.
  • At this operating point the engine returns -6 points for gap to target.
  • At this operating point the engine returns 30 count for affected count.
  • At this operating point the engine returns 500 count for total count.

How this compares with the baseline

  • Against the tool's baseline example, where rejected parts from this cavity sits at 12 parts and the headline result is 2.4 %, this scenario comes in 150% above the baseline at 6 %.
  • It computes the reject percentage for a single cavity by dividing that cavity's rejected parts by the total parts it produced. The value of this scenario is the size of the gap it exposes: that gap, priced out over a year, is the budget you can justify spending to close it.

Results at a glance

  • Rate: 6 % (headline result)
  • Gap to target: -6 points
  • Affected count: 30 count
  • Total count: 500 count

Run it with your numbers

  • Every input above is editable in the live Defect Rate by Cavity calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.