Plastic injection molding in China is a project workflow that should connect DFM, tooling ownership, material control, mold trials, inspection evidence, production validation, and communication. Country alone does not define quality; the supplier’s process, documentation, engineering depth, and accountability do.
For an overseas buyer, the most important decision is whether the supplier can turn a released design into an approved tool and repeatable parts. A low initial quote is not comparable if it omits DFM, mold corrections, inspection, packaging, shipping, or ownership of tooling data.
What to send before requesting a quote
- Released 3D CAD, 2D drawing, revision, material grade, color, annual volume, and target production date.
- Critical dimensions, cosmetic zones, surface finish, texture, assembly requirements, and functional tests.
- Preferred gate or parting-line constraints, insert requirements, expected cavity count, and packaging needs.
- Quality documents required: FAI, CMM, material certificate, process records, capability data, or customer-specific approvals.
Supplier evaluation checklist
| Area | Questions to ask |
|---|---|
| Engineering | Can the supplier provide DFM, moldflow review, gate proposal, draft analysis, and a written risk list? |
| Tooling | Who owns the mold, design files, electrodes, steel, spare parts, and maintenance records? |
| Quality | How are material lots, cavities, dimensions, appearance, and nonconformances recorded? |
| Trials | What evidence is supplied at T0/T1, how are corrections tracked, and who approves the tool? |
| Production | What process window, capacity, traceability, inspection frequency, and change-control system are used? |
Control the tooling and approval path
Approve the DFM report and mold design before steel is cut. At the first trial, review short shots, fill balance, gate vestige, ejection, cooling, dimensions, appearance, and cycle. Close corrections against a numbered report and require updated samples before production release. Do not treat a supplier’s factory photos or a certificate logo as a substitute for part-specific evidence.
The mold-making team can review steel, cooling, ejection, and tool ownership; the engineering team can define CTQs and approval evidence; the injection molding team can validate the production process.
Cost, communication, and risk
Compare quotes using the same material, cavities, steel, surface finish, trial quantity, inspection scope, packaging, shipping term, and correction responsibility. Agree on response times, design-change approval, intellectual-property handling, payment milestones, and escalation before sending sensitive production files. Contact Cavity Mold with your part data for a DFM and sourcing review.
Technical references
The Protolabs injection molding guide covers design, material, process, and inspection decisions. Xometry’s material-selection guide explains why resin choice affects performance, processing, and tooling requirements.