Injection Molding Gate Seal Study Analyzer

Screen a hold-time versus part-weight study for the first sustained weight plateau.

Formula and method

Interval change (%) = (current weight − previous weight) / previous weight × 100. A screened plateau requires two consecutive absolute changes at or below the user threshold.

Inputs and units

Enter increasing hold times and corresponding conditioned part or shot weights from the same cavity basis.

Worked example

Weights 10.00, 10.50, 10.68, 10.70 and 10.71 g at 0–4 s first meet a 0.2% two-interval plateau at 3 s.

When to use the study

Use when hold time is stepped while other molding conditions and total cycle timing are controlled.

How to interpret the result

The screened time is a measurement cue. Confirm dimensions, sink, appearance and—if available—cavity pressure before setting production hold time.

Assumptions and limitations

Part weight can plateau for reasons other than gate seal. Hot-runner gates, multi-gate parts and unstable check rings require additional evidence.

Validation guidance

Preserve machine, mold, material lot, melt/mold temperature, cycle state, units, instrument and sample order with the result. Repeat after any material, machine or tooling change.

FAQ

Why require two consecutive small weight changes?

One small interval can be measurement noise; two intervals provide a more conservative screen, but still require part-quality validation.

Related workflow

Process Validation & Stability hub · Scientific molding validation workflow · Weight measurement guide · Gate seal and pressure-drop setup

Sources

PlasticsToday: Scientific Molding, Part 1 · M. Holland: Monitoring Pressure Loss · BASF: Injection-Molding Problems · NIST: Measures of Scale · NIST: Coefficient of Variation · PMC: Filling Imbalance in Multi-cavity Molds · Hingtung: Cavity Balance Study