T1 vs T2 Mold Trial: What Gets Checked and What to Expect

Detailed engineering guide to T0, T1, and T2 mold sampling trials. Learn what gets inspected, CMM First Article Inspection reports, scientific molding windows, and sign-off criteria.

1. The Mold Trial Progression: From T0 to Mass Production Release

In custom injection mold manufacturing, the mold trial phase represents the moment of truth where weeks of 3D CAD design, Moldflow CAE simulation, precision CNC milling, wire EDM, and bench fitting are put to the physical test. Sourcing high-precision tooling requires a structured milestone progression through standardized trial stages: T0, T1, T2, and Mass Production (MP) Release.

Understanding what gets inspected at each trial stage—and knowing when an issue should be solved through molding parameter tuning versus tool steel modification—is essential for project managers, quality engineers, and procurement directors to avoid costly delays and ensure zero-defect production ramp-up.

At Axiom Molds, our trial center operates in-house injection presses from 50 to 3,000 tons equipped with RJG scientific molding transducers and robotic part extraction, ensuring every trial is fully transparent and repeatable.

2. T0: The Internal Dry-Run & Kinematic Verification

Before plastic resin is ever introduced into a new mold, Axiom Molds executes an internal T0 dry-run inspection on the assembly floor and trial press:

• Kinematic Stroke Verification: Verifying smooth slide movement, angular pin engagement, lifter travel, and ejector plate return without mechanical binding or galling.
• Hydraulic & Pneumatic Actuation: Testing core pull cylinders, unscrewing gearboxes, and valve gate manifolds for correct sequencing and limit switch signals.
• Cooling Circuit Pressure Testing: Subjecting all water circuits to a 10-bar (145 psi) hydrostatic pressure test for 30 minutes to verify zero internal seal or O-ring leakage.
• Hot Runner Electrical Diagnostics: Verifying thermocouple resistance, zone heater balance, and ground isolation on calibrated multi-zone hot runner controllers.

3. T1 Trial Protocol: Scientific Molding & First Article Inspection

The primary objective of the T1 trial is to establish a robust scientific molding process window and produce the first physical parts for comprehensive dimensional, visual, and functional inspection. The T1 trial follows a strict RJG scientific molding protocol:

1. Viscosity Curve (Rheology Study): Establishing the optimal injection speed by measuring effective melt viscosity across varying fill times to operate in the stable shear-thinning plateau.
2. Cavity Balance Study: Performing progressive short-shot fills (50%, 75%, 90%, 95%) to confirm that all cavities fill simultaneously within ±0.5% part weight variance.
3. Gate Seal (Freeze-Off) Analysis: Incrementally increasing hold time while weighing molded parts until part weight stabilizes, establishing minimum packing time.
4. Cooling Time DOE: Optimizing water flow rates (achieving turbulent flow with Reynolds number > 4,000) to find the fastest cycle time that prevents post-ejection part warpage.

4. Comparative Analysis: T1 vs T2 Trial Deliverables

The operational scope, quality checkpoints, and deliverables of T1 and T2 trials serve complementary purposes in tooling qualification:

5. Root Cause Troubleshooting: Steel Modification vs Process Tuning

When dimensional deviations or visual defects appear during T1, an experienced tooling engineer must differentiate between process-induced variations and true steel machining errors:

• Sink Marks: Typically resolved by increasing pack/hold pressure or extending gate seal time. If sink persists on thick ribs, the core steel must be modified to thin the rib base.
• Weld Line Weakness: Addressed by increasing melt and mold temperatures or accelerating injection speed. If knit lines remain in critical snap zones, gate locations must be modified.
• Linear Dimensional Discrepancies: If a dimension is consistently undersized across all cavities under optimal packing pressure, the steel is “steel-safe” and can be opened with a light CNC or EDM skim pass (±0.002mm on Makino V33i).
• Flashing: Caused by parting line mismatch, insufficient clamping tonnage, or excessive injection pressure. Requires bluing paste spotting and precision hand-lapping to achieve >90% contact area.

6. T2 Validation and Factory Acceptance Testing (FAT) Release

Following approval of T1 corrective actions, toolmakers apply the final surface texture (e.g., Mold-Tech MT-11010 or SPI A-2 mirror finish) and assemble final production components for the T2 trial.

During T2, the mold undergoes a continuous 4-hour dry-cycle endurance test and a 300-shot production run to generate statistical process capability metrics (Cpk/Ppk ≥ 1.67). Upon passing all FAT criteria, the mold is prepped with VCI anti-rust oil and crated for export. Review our complete mold trial capabilities and our 8-point mold acceptance checklist.

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