Choosing an injection molding supplier in China is not only a purchasing decision. It is an engineering, tooling, quality and communication decision. Use this checklist before you pay for a mold.
1. Product Fit
Ask whether the supplier has made parts similar to yours in:
- Resin type
- Part size
- Cosmetic standard
- Tolerance level
- Assembly function
- Annual production volume
The best supplier is not always the largest factory. It is the supplier whose process matches your part.
2. Mold Specification
Your quote should clearly state:
- Mold steel
- Cavity count
- Mold life expectation
- Runner type
- Gate type and location assumptions
- Texture or polish level
- Sample quantity included
- Engineering change policy
If the quote does not define the mold, you cannot compare it fairly.
3. DFM Review
A serious supplier should review manufacturability before final tooling. They should look at draft angles, wall thickness, ribs, bosses, undercuts, shrinkage, warpage and likely cosmetic risks.
Ask for the DFM comments in writing. This makes later sample discussions much easier.
4. Material and Resin Control
Confirm whether the supplier can source the required resin grade and whether they understand drying, shrinkage, color matching and recycled material restrictions.
For regulated or performance-critical parts, ask for material certificates and traceability.
5. Quality Control
Ask for the inspection plan before production starts. At minimum, the supplier should explain:
- First article inspection
- Critical dimensions
- Cosmetic criteria
- In-process sampling frequency
- Final inspection method
- Defect handling
- Sample retention
If your product has tight tolerances or safety requirements, define the inspection standard before mold construction.
6. Communication
Good suppliers make assumptions visible. They ask questions, confirm details and document decisions.
Poor suppliers avoid details until there is a problem. That delay often appears during sampling, when mold changes become expensive.
7. Payment and Ownership
Clarify:
- Tooling payment schedule
- Mold ownership
- Mold storage terms
- Maintenance responsibility
- Transfer options if you move production
- Production payment terms
For custom products, mold ownership should be documented before payment.
8. Export and Packaging
Injection molded parts can be damaged by poor packaging, especially cosmetic covers, transparent parts, painted parts and assembled components.
Ask the supplier to confirm packaging method, carton strength, labeling, palletization and export documentation.
Final Supplier Scorecard
Use a simple 1 to 5 score for each area:
| Area | Score |
|---|---|
| Product fit | |
| Mold specification clarity | |
| DFM quality | |
| Material knowledge | |
| Quality control | |
| Communication | |
| Export readiness | |
| Commercial terms |
The winning supplier should be the one with the best total project fit, not simply the lowest mold price.