A capable plastic injection mold maker should translate your part requirements into a tool that can be sampled, maintained, inspected, and run repeatedly—not just quote a cavity shape. Compare engineering depth, tooling ownership, construction plan, quality feedback, communication, and production support before choosing on price.
What to evaluate in a plastic injection mold maker
| Capability | Questions to ask |
|---|---|
| DFM and mold design | Will the maker review draft, walls, gates, vents, slides, lifters, cooling, ejection, and parting line before steel? |
| Machining and assembly | Which operations are controlled in-house, and how are CNC, EDM, polishing, fitting, and inspection coordinated? |
| Tool ownership | Who owns the mold, where is it stored, who authorizes changes, and can it be transferred later? |
| Sampling | What is included at T1, what data is measured, and how are corrections tracked? |
| Maintenance | What cleaning, lubrication, cooling, vent, spare-part, and repair records are provided? |
The Plastics Technology Alliance supplier capability checklist recommends evaluating tooling approach, process capability, documentation, ownership, and transferability rather than treating a quote as proof of production readiness.
Review the part before the mold
A mold maker should identify manufacturability risks before machining: inadequate draft, non-uniform walls, deep ribs, sharp corners, difficult shutoffs, undercuts, gate restrictions, poor vent locations, uneven cooling, or ejection interference. Ask for proposed changes and the effect on cost, cycle, appearance, dimensions, and maintenance.
For complex parts, confirm whether the mold maker can work with the molder on flow analysis, material shrinkage, cavity balance, mold temperature, machine limits, and T1 acceptance. A tool that is easy to machine but difficult to process is not a successful production tool.
Tool construction questions
- What mold base, insert material, standard components, cavity count, runner system, and steel treatment are proposed?
- How will the mold handle gate vestige, venting, cooling, parting line, slides, lifters, and ejection?
- Which areas are replaceable inserts or wear components?
- How are steel changes, dimensional corrections, and engineering revisions approved?
- What drawings, spare lists, maintenance instructions, and inspection records are delivered with the tool?
How to compare mold makers fairly
- Send the same CAD revision, drawing, resin, volume, cosmetic requirement, and acceptance criteria to each candidate.
- Compare the DFM response before comparing price.
- Separate tool cost, sampling, corrections, transport, documentation, and production molding assumptions.
- Confirm who owns the tool and what happens if the molder or toolmaker changes.
- Use T1 data and documented corrective actions to decide whether the tool is ready for production.
Review Cavity Mold’s mold-making service, engineering support, and injection molding service. Contact the team with the part files, resin, volume, and required tool documentation.
