Last updated: 2026-09-05 · 5 min read
Mold Trial Material Qualification — What Tests Must You Run at T1 to Confirm the Resin Meets Specifications Before Mass Production?
Material qualification at mold trial (T1) verifies that the resin grade produces parts meeting all specifications before mass production begins. Tests include: dimensional check (CMM against drawing, ±0.05–0.15mm tolerance verification), visual inspection (short shots, flash, sink, weld lines), mechanical testing (tensile, impact if required), and resin verification (MFI check, ash content for GF resins). T1 qualification takes 1–3 days and produces the baseline data for all future production.
- Material qualification tests at T1: (1) Dimensional — CMM measures 5–10 critical dims on 3–5 parts; results compared to drawing tolerance (±0.05–0.25mm). (2) Visual — inspect for short shots, flash, sink, weld lines, flow marks, burns. (3) Functional — snap fit force, insert pull-out, assembly fit check. (4) Resin verification — MFI test (confirms grade), ash content (confirms GF%), moisture (confirms drying). Each result documented in T1 report with photos, CMM data and resin lot number.
- Resin verification prevents wrong-material defects: MFI test — each grade has a specified range (ABS: 15–25 g/10min, PC: 8–12 g/10min). Outside range = wrong grade or degraded material. Ash content — for GF resins: burn off resin, weigh remaining glass. Target: 30% ±3% for GF-PA6, 20% ±3% for GF-PP. Moisture — hygroscopic resins (PC, PA) must be dried: PC ≤0.02%, PA ≤0.05%. Excess moisture causes hydrolysis → impact strength drops 30–50%.
- T1 qualification produces three deliverables: (1) T1 report — photos of all parts, dimensional data (CMM report in English GD&T), resin lot number, processing parameters (melt temp, injection speed, hold pressure, cycle time). (2) Approved sample set — 3–5 parts labeled with mold number, date, cavity number, resin lot. Stored as the golden reference for production comparison. (3) Parameter card — locked molding parameters for mass production. Any change requires documented approval with before/after CMM data. The T1 report is the baseline: all future production is compared against it.
What Five Tests Confirm the Resin and Process Produce Conforming Parts at T1?
| Test | Method | Accept Criteria | Fail Action |
|---|---|---|---|
| Dimensional (CMM) | 5–10 critical dims, 3–5 parts | All within drawing tolerance | Adjust shrinkage compensation, re-cut |
| Visual | Inspect under 500 lux light | No short shot, flash, sink, weld | Adjust parameters or modify gate |
| Functional | Assembly fit, snap force test | Passes go/no-go gauge | Modify dimension or geometry |
| MFI verification | Melt flow indexer test | Within resin datasheet range | Reject material, confirm correct grade |
| Moisture content | Moisture analyzer (halogen) | PC ≤0.02%, PA ≤0.05% | Re-dry resin, check dryer performance |
T1 qualification is the last gate before mass production. If any test fails: the mold does not ship. The most common T1 failure: dimensional drift from incorrect shrinkage compensation in the mold design. Fix: adjust cavity dimensions (safe to remove material, impossible to add). Second most common: short shots from insufficient gate size. Fix: enlarge gate or add vents. Each failure mode is documented and corrected before T2.
Golden sample — a T1-approved part labeled with mold number, date, cavity number and resin lot, stored as the physical reference for all future production. During mass production, parts are compared against the golden sample for visual defects (color, surface finish, gate vestige). If production parts differ: investigate the process change. The dimensional drift guide covers how SPC monitoring detects drift from the golden baseline.
What Three Steps Ensure Material Qualification Is Complete and Documented Before Mass Production?
- Run all five T1 tests and document every result with photos, CMM data and resin lot number. The T1 report must include: part photos (all cavities, all views), CMM report (English GD&T, actual values vs. nominal), resin lot number and MFI test result, processing parameters (melt temp, injection speed, hold pressure, cycle time, mold temp). If any dimension is out of tolerance: record the deviation and the corrective action. The T1 report is the baseline for mass production — future parts are compared against it.
- Approve and label the golden sample set — 3–5 parts stored as the production reference. Each sample is labeled with: mold number, date, cavity number, resin lot number. The golden samples are stored in a controlled environment (sealed bag with desiccant for hygroscopic resins). During mass production: compare production parts against the golden samples for visual defects (color, surface finish, gate vestige). If production parts differ from golden samples: investigate the process change (resin lot change? mold wear? parameter drift?).
- Lock the parameter card — any change requires documented approval with before/after CMM data. The parameter card records: resin grade and supplier, melt temperature range, injection speed, hold pressure and time, cooling time, mold temperature, cycle time. The card is password-protected in the machine controller. Any parameter change during mass production requires: (1) documented reason, (2) CMM measurement before and after the change, (3) quality engineer approval. This prevents uncontrolled changes from introducing dimensional drift or new defects.
Ash content test — a method to verify the glass fiber percentage in a GF resin. A known-weight sample is burned in a furnace at 600°C until all resin is consumed; the remaining ash (glass fiber) is weighed. Target: 30% ±3% for GF-PA6, 20% ±3% for GF-PP. Below target: the resin has less reinforcement than specified, reducing stiffness and strength. The resin datasheet guide shows where to find the specified glass fiber content on the TDS.
Material qualification at T1: dimensional (CMM), visual, functional, MFI verification, moisture check. Produces: T1 report, golden samples, locked parameter card. Any test fails: mold does not ship. All future production compared against T1 baseline.
- CMM dimensional check — 5–10 critical dims on 3–5 parts, all within drawing tolerance.
- Visual inspection under 500 lux — no short shots, flash, sink, weld lines.
- MFI verified within datasheet range — confirms correct grade, not degraded.
- Moisture within spec — PC ≤0.02%, PA ≤0.05% before molding.
- Parameter card locked — password-protected, change log with CMM before/after.
Frequently Asked Questions
How many T1 samples are needed for material qualification?
Typically 3–5 parts from different cavities (for multi-cavity molds: at least one part per cavity). Each part is measured on the CMM to confirm cavity-to-cavity consistency. For high-cavity molds (16+ cavities): measure 1 part per cavity for the first 5,000 shots, then reduce to 1 part per 4 cavities. The sample count depends on part complexity: simple parts (brackets, clips): 3 parts minimum. Complex parts (housings, connectors with 20+ critical dimensions): 5 parts minimum. More samples provide better statistical confidence but increase T1 cost and time.
What if the resin passes T1 but fails during mass production?
Three diagnostic steps: (1) Compare production parts against T1 golden samples — if dimensions differ: check if resin lot changed. (2) Check processing parameters — if changed: revert to T1 baseline and measure again. (3) Check mold condition — if 50,000+ shots: gate wear may cause drift. Most common cause: resin lot change (different MFI or shrinkage). Fix: adjust parameters within the locked range, or switch back to original lot. If original lot exhausted: run mini T1 with new lot.
Do I need to re-qualify the material if I change resin suppliers?
Yes. Switching suppliers (even same grade name) requires re-qualification: MFI may differ ±10–15%, shrinkage ±0.05%, additives package differs (color, UV, impact). Re-qualification: run T1 with new supplier’s resin, measure CMM dimensions, compare against original baseline. If within tolerance: approve new supplier with updated parameter card. If out of tolerance: adjust shrinkage compensation or reject the supplier. Always qualify at least 2 suppliers for critical resins to avoid single-source dependency.
Key Takeaways
- T1 tests: dimensional, visual, functional, MFI, moisture.
- Deliverables: T1 report, golden samples, locked parameter card.
- Any test fails: mold does not ship to production.
- Resin supplier change = re-qualification required.
Send the part drawing, resin grade and specification requirements — the review defines the T1 material qualification test plan, specifies the CMM measurement points, and documents the acceptance criteria before the mold trial begins.
Sources: Plastics Technology — Mold Trial Procedures and T1 Qualification · Plastics Technology Online — Material Verification at Mold Trial · Society of Plastics Engineers (SPE) — T1 Sampling and Qualification Protocols · Quality Magazine — First Article Inspection for Injection Molding · ThomasNet — Mold Trial and Material Qualification Best Practices
— Arthur, Tooling Engineer at aCatMould