Double Shot Injection Molding
Double shot (also called 2-shot or multi-shot) injection molding molds two different materials or colors into one part in a single machine cycle. The result: soft-touch grips, integrated seals and two-color aesthetics that would otherwise require glue, press-fit or a second operation.
Where Double Shot Pays Off
Soft-touch grips
Rigid handle + TPE overmold for ergonomic, non-slip comfort in one shot.
Sealing lips
A flexible TPE or TPV seal molded directly onto a rigid structural body.
Multi-color aesthetics
Two contrasting colors in a single part — no paint, no secondary assembly.
Electrical insulation
Insulating layer over conductive substrate for connectors and housings.
Gaskets & boots
Integrated elastomeric gasket that cannot loosen or be mis-assembled.
Double Shot vs Overmolding vs Glue
CycleTwo materials in ONE cycle on a rotary or index platen — faster than mold-and-assemble.
BondChemical/mechanical interlock between the two melts — stronger than glue.
ToolingTwo-cavity or rotating-core tool; higher upfront cost, lower per-part cost at volume.
vs OvermoldingOvermolding runs two cycles (substrate first, then second shot). Double-shot does it in one.
Design Rules We Enforce
- ✓Pick a compatible resin pair (e.g. PP+TPE, PC+TPU) — bond strength lives or dies here.
- ✓Design mechanical interlock (undercuts, textures) so the bond is structural, not just cosmetic.
- ✓Keep wall sections compatible on shrink and processing temp to avoid warpage.
- ✓Plan gate and rotation sequence early — it dictates tool cost more than part geometry.