Parting Line Design for Two-Part Silicone Production Molds
Parting line design for two-part silicone molds - flash control, registration keys, draft, and MOQ 50 production trays that close clean.
Kyler Yang · Founder5 min read
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A bad parting line turns every pour into flash trimming overtime. RUUIPON designs two-part custom silicone molds at MOQ 50 so the split follows the widest silhouette, not the prettiest CAD screenshot.
Quick answer: Split at the maximum projected outline, add registration keys, keep 1-3 deg draft where possible, plan vents/pour gates, and approve flash height on the prototype before production.
Parting Line Rules
| Rule | Why |
|---|---|
| Split at widest section | Minimizes undercut lock |
| Avoid faces across logos | Flash cuts lettering |
| Keys outside cosmetic faces | Alignment without witness marks |
| Walls 2.5-5 mm | Stiffness at the split |
| Spacing 8-20 mm | Web strength between cavities |
Where to Split
Figurines and 3D resin pieces need the parting line on a natural silhouette edge. Cutting through a logo face creates a witness line on every cast - undercuts and draft.
Flash Control
Flash is silicone squeezed at the split. Reduce with flat mating faces, proper clamp pressure, and Shore A matched to the job. Trimming QC: flash trimming QC.
Registration Keys
Keys stop lateral slip. Place them outside cosmetic zones - registration keys guide.
Draft and Vents
Pour gates and vents belong on the parting or dedicated channels - pour spout and vent design.
QC at Sample
Prototype in 3-7 days, cast 5-10 shots, measure flash, then lock production at MOQ 50. Checklist: sample approval.
Frequently Asked Questions
One-part instead?
Flat-back parts often yes - two-part vs one-part.
Can flash be zero?
Aim for trim-light, not theoretical zero on soft tools.
MOQ / lead time?
MOQ 50; prototype 3-7 days.
Contact?
[email protected] | +86 135 3006 2969 | Contact.
Ready to order custom silicone molds?
Free quote for OEM/ODM projects. MOQ 20 · Prototype 3-7 days · FDA/LFGB available.