Cold edge or tab gate
- Runner slug each cycle
- Simpler mold for low cavitation
- Gate on parting when geometry allows
DFM
Hot Tip Gates: Injection Molding Design Rules
Hot tip gates inject molten plastic through a heated drop with different witness and scrap tradeoffs.
DFM
Hot tip gates drop plastic straight into the cavity
Manifold heat changes gate witness and color change behavior versus cold edge gates.
Hot tip systems keep plastic molten in the drop zone, which reduces runner scrap on many programs.
Tip location on cosmetic surfaces still leaves a witness that must be accepted or hidden.
Sensitive resins can degrade if tip temperature and residence time are not controlled.
DFM
Quote this rule with your CAD upload
NetProto DFM review flags these geometry patterns before steel is ordered.
- Call out draw direction and cosmetic faces on the model.
- Note resin family even when the grade is not final.
- Tighten tolerances only on mating features that need them.
Systems
Hot tip drop versus cold edge gate
Capital and maintenance sit on the hot side. Scrap and trim sit on the cold side.
Hot tip gate
- Less runner mass per shot on many layouts
- Manifold service and tip wear items
- Useful when gate must stay on a flat cosmetic face
Related rules
Design guide
Jump to sibling rules before you freeze CAD.
Design guide hub
All DFM topics on one route.
Design guide hubDFM article
Long form engineer guide.
DFM articleGate types
Compare gate families.
Gate typesGate location
Cosmetic and fill map.
Gate locationHot runner glossary
Manifold vocabulary.
Hot runner glossaryVisual reference
Molding context for this rule
Images from the Forge media library illustrate typical programs.
Injection molded part design review on CAD
Injection molded part design review on CAD
Plastic housing with ribs and bosses
Plastic housing with ribs and bosses
Engineer measuring molded component
Engineer measuring molded component
FAQ
Hot tip questions
Are hot tips the same as hot runners?
Hot tips are one hot runner gate style. Full manifolds vary by vendor.
Can hot tips change color quickly?
Color changes still purge heated volume. Plan scrap for the first shots.
Who selects hot tip diameter?
Mold designer on qualified tooling programs after DFM review.
Next step
State gate witness limits on CAD
Upload cosmetic map and resin notes before manifold scope is fixed.