Unlike thermoplastic materials, LSR does not solidify upon cooling inside the mold but cures through heat-activated cross-linking. During this process, the material behaves almost like a low-viscosity fluid under pressure. Studies show that flow direction and cavity geometry strongly influence shrinkage distribution, meaning mold design must anticipate anisotropic deformation after curing and demolding.
Cold runner systems are widely used in precision LSR molding to minimize material waste and prevent premature curing. Needle valve gating further enhances control by isolating flow until injection pressure reaches a stable level, ensuring clean and consistent cavity filling.
Because LSR has extremely low viscosity, even microscopic gaps can cause flash defects. Proper venting channels are therefore essential, but they must be carefully balanced to avoid material leakage. The parting line design becomes a critical sealing interface rather than just a structural boundary.
LSR typically exhibits 2%–4% post-curing shrinkage depending on formulation and process conditions. Mold designers must compensate for this behavior by adjusting cavity dimensions and considering flow-direction-dependent shrinkage differences.
Surface finish directly influences demolding behavior. Highly polished surfaces may increase adhesion, while controlled texturing improves release efficiency. Since LSR is elastomeric, undercuts can often be released without mechanical sliders, simplifying mold architecture.
Minimal draft is needed because silicone is flexible and can deform during demolding.
It reduces waste and prevents premature curing inside the runner system.
Mainly insufficient sealing precision at the parting line due to low material viscosity.
