Injection Mould Cavity Surface Roughness Measurement Using Silicon Replicas
Indirect silicone replica metrology resolves deep mould cavity roughness parameters non-destructively within five percent variance of direct steel scans.
Addition-Cure Silicone
Meaning
Platinum-catalyzed elastomers solidify through an internal reaction between vinyl-terminated siloxanes and hydride-functional crosslinkers. Addition-cure silicone avoids byproduct generation during this polymerization, which permits the creation of parts with low shrinkage and high dimensional stability. Because no volatile small molecules escape the matrix, the material remains suitable for thick-section moulding and rapid thermal processing cycles.
Curing Dynamics
Thermal energy triggers the catalyst to bridge reactive groups within the liquid polymer base. An addition-cure silicone formulation often requires a strict mixing ratio to ensure every crosslinking site finds a partner. Any deviation from the specified weight ratio produces tacky surfaces or soft spots in the bulk of the part.
Moulders control the reaction speed by adjusting the mould temperature or by introducing inhibitor packages that extend shelf life.
Economic Variables
Material costs remain higher for this system compared to peroxide-initiated alternatives due to the inclusion of precious metal catalysts. High raw material prices shift the focus toward optimizing cycle times to maximize throughput per mould cavity. Virgin supply chains prioritize high-purity ingredients to protect the platinum species from poisoning by sulfur or nitrogen contaminants found in secondary regrind streams.
Recycled rubber often loses the precise balance needed for the catalytic reaction, which renders clean scrap difficult to reprocess without significant downgrading of physical properties.
Performance Boundaries
Tensile strength and tear resistance depend upon the density of the covalent network formed during the heating phase. A datasheet value for hardness represents a laboratory target that ignores the influence of cavity pressure and cooling time variations. When the crosslink density drops, the cured elastomer exhibits poor compression set and dimensional drift under load.
Correct processing parameters maintain the intended molecular architecture that defines the mechanical behavior of the molded final product.