03.01 Tooling Engineering: T0–T2 Mold Trial Acceptance, Mold Modification Line Stops, and DFM Review
Governance metadata | Owner: Head of Supply Chain | Last reviewed: 2026-10-22 | Next review: 2027-01-31
Core principle: the mold is the physical mother of hardware mass production, and a mold modification is the biggest black hole for cost and lead time. Any hesitation before tooling costs 100 times less than the rework after tooling. This manual standardizes the end-to-end GTM control points from the DFM manufacturability review through T0~T2 mold-trial release.
1. The GTM Eight-Item Final Review Checklist for DFM (Design for Manufacturability)
Before signing the tooling confirmation (Tooling PO), the GTM operator must work with structural engineering and the mold factory to complete the following final review:
| Review subject | Structural tolerance and physical standard | GTM commercial impact | Pitfall-avoidance red line and decision threshold |
|---|---|---|---|
| Draft angle (Draft Angle) | Main housing body ≥1.5°~2.0°; each additional 0.02mm of texture depth adds 1° | Determines whether ejection scratches the appearance, which drives the CVR | A draft angle <0.5° is strictly forbidden — injection ejection would inevitably scrape and scrap the part |
| Wall thickness uniformity (Wall Thickness) | Main wall thickness 2.0mm ~ 2.5mm, with adjacent wall thickness difference ≤25% | Prevents surface sink marks and directly determines the feel of the first launch | The thickness of ribs / screw-post roots must never exceed 60% of the main wall thickness |
| Gate position and weld lines (Gate & Weld) | Avoid exposed faces and load-bearing snaps; use a submerged gate or hot runner | Weld lines affect drop strength and CMF visual quality | The gate must never be placed in the antenna keep-out zone or near the optical lens window |
| Ejector pins and parting line (PL: Parting Line & Ejector) | Ejector pins are placed on the hidden inner side; parting-line step ≤0.03mm (note: here PL means the mold parting line, not the financial P&L) | A scratchy hand feel and uneven gaps are high-frequency sources of negative reviews | The mold factory is strictly required to deliver a 3D mold flow analysis (Moldflow) report |
| Material shrinkage rate of structural parts | PC+ABS shrinkage is calculated at 0.5%; POM at 1.8% ~ 2.2% | Assembly interference drives yield below 90% | Brittle pure PC is forbidden for core load-bearing snaps — fiber reinforcement or an alloy change is mandatory |
| Mold life and cavity count (Cavity) | Tool steel S136 / NAK80; 1×2 or 1×4 cavities | Determines the reorder capacity ramp ceiling and the per-unit depreciation cost | High cavity counts such as 1×8 are strictly forbidden for the first pilot build, because they easily cause dimensional drift between cavities |
| Public-mold leakage prevention | The mold cavity is engraved with a brand-specific embossed logo and an anti-counterfeit secret mark | Prevents the contract manufacturer from secretly cutting a public mold and selling white-label goods | The tooling steel is covered by a physical ownership agreement (see 03.02 Contract Manufacturing Control and Guaranteed Yield Agreement) |
| Packaging fit interference | The maximum dimensional tolerance of the outer shape is folded into the color box inner-liner tolerance | A size tier jump causes FBA freight to balloon | Reserve a +1.5mm clearance for the length, width, and height tolerances of the whole unit |
2. The Three-Stage Release Gate for T0 ~ T2 Mold Trials and Pilot Production (Gate Standard)
[Tooling PO issued] ➔ [T-45D T0 mold trial samples] ➔ [T-30D T1 structural assembly] ➔ [T-15D T2 CMF sign-off sample] ➔ [PVT small-batch pilot production]
│ │ │ │ │
Pay 50% deposit Focus on short shots / sink marks Assembly fit / snap strength Color diff / texture / silkscreen Yield must be >95% (entering [01.09 GR3 Launch Readiness Gate])| Mold trial stage | Core task | Sample quantity | Acceptance release threshold | Delay liability definition and accountability |
|---|---|---|---|---|
| T0 mold trial (first sample run) | Verify smooth mold motion and troubleshoot severe short shots, flash, and uneven resin flow | 10~20 sets (natural/unpainted parts) | No blowholes and no mold sticking; dimensional tolerances meet the 3D drawing at ±0.15mm | Design defects in the mold are repaired free of charge by the mold factory, with no schedule extension |
| T1 mold trial (structural assembly validation) | Assemble the full set of structural parts to validate snap fit, screw torque, and sealing | 30~50 sets (with parts assembled) | Passes the 1.0 meter drop test; whole-unit gap step ≤0.10mm | A mold modification caused by a product spec change is borne by the brand side, both in cost and in schedule |
| T2 mold trial (CMF and appearance sign-off) | Finalize the spray coating, electroplating, laser engraving, and texture (grain) effects, and confirm at pilot production | 50~100 sets (finished color) | CMF samples are within Delta E <1.0 of the color chip; abrasion and sweat-resistance testing passes | Once the mold is textured, plastic cannot be added back in reverse; the GTM and design must co-sign |
3. Mold Modification Line-Stop Loss Accounting and Liability Adjudication Rules
In hardware manufacturing, a single mold modification typically causes 7 ~ 14 days of line downtime, directly threatening the launch-readiness milestone of the 01.09 GR3 Launch Readiness Gate. Mold modification losses are adjudicated under the following rules:
Adding plastic is easy; removing plastic is hard:
- Removing plastic (machining it out of the mold steel): on the product this shows up as "adding plastic / thickening", with a CNC/EDM machining cycle of 3~5 days and no loss of mold life;
- Adding plastic (welding the mold steel back): on the product this shows up as "removing plastic / thinning", requiring laser welding or a mold core insert, with a cycle of 7~12 days, a 30% loss of local mold life, and a tendency to leave burn marks.
Mold modification cost and liquidated damages adjudication table:
| Cause of the mold modification | Liable party | Cost bearer | Responsibility for schedule delay | GTM operator corrective action |
|---|---|---|---|---|
| Mold machining out of tolerance (tolerance exceeded) | Mold factory | Mold factory bears 100% | Mold factory pays liquidated damages for lost production time | Activate the sourcing comparison with backup mold suppliers for contingency reference |
| Product definition change (a feature added on the spot) | Brand R&D | The brand side pays the mold modification cost | The launch schedule is pushed back and counted in the R&D performance review | Convene an emergency PCT review to weigh the delay loss against the selling-point gain |
| Interference not identified during the DFM stage | R&D and the contract manufacturer jointly | Each bears 50% | The two sides negotiate to compress the T2 validation cycle | Draw on the standby air-freight budget to recover logistics time (see 03.05 Rolling 8-Week PSI Production-Sales Balance Sheet) |
4. Full-Cycle Mold Trial Checklist
[ ] 1. The DFM report is 100% signed off, and the 3D mold flow analysis shows no severe voids and no unacceptable weld lines.
[ ] 2. The mold steel supplier's material certificate (factory spectral inspection report) is archived; passing off domestic substitute material as imported S136 is strictly forbidden.
[ ] 3. The T0 first-sample coordinate measuring machine (CMM) full-dimension inspection report has a pass rate ≥90%.
[ ] 4. The T1 assembly drop test (front face, bottom face, and each corner once, from 1.0 meter) shows no snap breakage.
[ ] 5. The T2 CMF appearance sign-off is completed under a standard light source box (D65/TL84) with multi-illumination comparison.
[ ] 6. The final tooling ownership nameplate has been riveted to the mold base surface, making asset ownership explicit.
5. Shop-Floor Counter-Defense Line: "Zero Sprue Material" Raw Material and Infrared Spectroscopy Penetration Spot Checks
In the Dongguan and Shenzhen manufacturing workshops, the most common hidden operation, under the pressure of "mold shrinkage and cost", is for the contract manufacturer to secretly blend 30%~50% of "sprue material / recycled regrind" into virgin PC+ABS. Although it is hard to detect on the appearance of T0~T2 samples, once the bulk shipment reaches the US and European markets and goes through a cold winter or a summer ocean crossing, the concentrated internal stress in the plastic will cause brittle snap breakage, housing bursting, and mass returns.
1. The "Four-Level Physical Lockdown" Procedure for Raw Material Entry to the Factory
Raw material sealed-sample baseline: during the project definition phase, branded plastic pellets (e.g. Sabic, Bayer) must be purchased from the original manufacturer, and the brand side and the factory must jointly sign a three-party direct-supply agreement for injection pellets;
Unannounced hopper sampling right: the contract explicitly grants the brand's resident SQE (supplier quality engineer) the unrestricted right to take samples on the spot from the injection machine head hopper at any time without advance notice;
Infrared spectroscopy (FTIR) penetration testing and full-coverage loss compensation claims: before the injection of each bulk batch, samples are sent to a national third-party laboratory for FTIR infrared spectroscopy analysis and thermogravimetric analysis (TGA). As long as an abnormal molecular weight distribution or a characteristic impurity peak is detected (a judgment of sprue material / regrind adulteration):
- Full-coverage liquidated damages: under the liability-for-breach rules in Article 585 of the Civil Code of the People's Republic of China, the contract must not set an unrealistic, inflated punitive multiplier (in judicial practice, an amount excessively higher than the loss is usually reduced by the adjudicating court); instead it must establish a full-coverage liquidated damages mechanism: besides paying liquidated damages of 30% of the total order value of that batch, the contract manufacturer must also compensate in full all actual losses caused by the regrind (including, without limitation, the total scrap-and-remake loss of all injection parts, the lost-time cost of line downtime, line clearing and waiting for material, mold cleaning and maintenance costs, return logistics ocean freight, and overseas end-customer recall complaint compensation);
- Non-monetary relief and immediate tooling recovery: the brand side has the right to unilaterally and unconditionally shut down and seal the line on the spot, deduct the contract manufacturer's outstanding processing fees and quality deposit in full, and to hoist and recover the tooling owned by the brand at any time without condition.