Pick a mold type and watch one full molding cycle in cross-section: injection, cooling, each parting line opening, ejection and what falls out of the mold. Then compare cost, scrap and cycle time, and let the selector suggest a structure for your part.
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| 2-Plate | 3-Plate | Hot Runner | |
|---|---|---|---|
| Parting lines / openings | 1 | 2 parting lines, 3 opening strokes | 1 |
| Gate location | Part edge on the parting line (side, fan, tunnel/sub gate) | Almost anywhere on the cavity face (pin-point gates) | Almost anywhere (open nozzle or valve gate) |
| Runner scrap per shot | Sprue + runner | Sprue + runner + drops (usually the most) | None (cold sub-runner only in hybrid designs) |
| Degating | Manual cut, or automatic with tunnel gate | Automatic — gates snap off on opening | Not needed |
| Cycle time (typical) | Baseline | Slightly longer: longer stroke, thick runner must cool | Often 10–30% shorter: no runner to cool |
| Mold cost (typical) | Lowest | ≈ +15–30% vs 2-plate | ≈ +30–60%+; hot runner system adds roughly $2k–$30k+ by drop count |
| Machine needs | Standard | More daylight / opening stroke | Temperature controller zones |
| Maintenance | Simple | Moderate: puller pins, latches, stop bolts | Highest: heaters, thermocouples, nozzle tips, leaks |
| Colour / material change | Fast | Fast | Slower — manifold must be purged |
| Best for | Low–medium volume, edge-gated parts, tight budgets | Centre- or multi-point gating on a cold-runner budget | High volume, cosmetic parts, expensive resins, multi-cavity |
Cost and cycle figures are typical ranges from our tooling projects, not quotes. Actual numbers depend on part size, cavitation, resin and the hot runner brand.
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Not sure which structure your part needs?
Send us your 3D file. Our engineers will recommend the gate and runner layout with a free DFM review.