Plastic injection mold selection should match part geometry, cavity count, runner system, production volume, cycle, automation, maintenance, tooling cost, and change risk. Two-plate, three-plate, family, multi-cavity, stack, cold-runner, hot-runner, insert, and side-action solutions each trade simplicity against output or geometry.
Compare the main mold choices
- Two-plate molds: practical for many straightforward parts when gate and runner layout fit the design.
- Three-plate molds: useful when a different gating arrangement or automatic separation supports the part and production plan.
- Single-cavity and multi-cavity molds: balance investment, output, cavity balance, inspection, and maintenance.
- Family molds: can mold related components together but require careful flow, packing, and dimensional balance.
- Stack molds: increase output per machine footprint but add alignment, service, and tooling complexity.
- Side actions, inserts, and special runners: enable geometry or process goals while adding cost and maintenance.
Choose with the whole lifecycle in view
Review volume, annual demand, part revisions, material, cosmetic requirements, gate vestige, scrap, automation, mold ownership, spare parts, and machine fit. The cheapest mold type at quotation may not be the lowest total cost once cycle time, maintenance, changeover, and inspection are included.
Plan the next step
Share your part, resin, annual volume, critical dimensions, finish, and timing with the Cavity Mold team through our contact page. We can review the manufacturing risks and recommend a practical next step.
Related Cavity Mold resources
- Injection mold making services
- Injection mold engineering services
- Plastic injection molding services
- Contact Cavity Mold
Technical references
- Xometry injection molding types
- Protolabs family and multi-cavity molding
- Xometry injection molding side actions
Choose architecture by consequence
Mold type is a design decision with consequences for gating, runner waste, cycle, automation, maintenance, parting, actions, and inspection. Start with the part and production boundary, then compare architectures.
| Decision | What to check | Boundary |
|---|---|---|
| Parting and release | Check parting line, draft, undercuts, ejection, shutoffs, and cosmetic surfaces. | A simpler mold may require a design change or accept a visible gate. |
| Cavity strategy | Compare single, family, and multi-cavity balance, sampling, and expansion. | Cavity count must fit demand and process control. |
| Feed system | Compare cold-runner waste, hot-runner control, color changes, maintenance, and gate evidence. | The system changes both process and service work. |
| Service boundary | Review access, spares, cleaning, repair, and operator skill. | Choose the tool that can be operated and maintained after launch. |
Architecture decision path
- Write the part and volume assumptions.
- List the architecture options that solve the release problem.
- Compare consequences for process, quality, cost, and maintenance.
- Document the selected boundary before quoting.
Review options in engineering and convert the selected architecture into a tooling scope.