Interfacial Area Ratio Sdr

Surface Expansion

Calculation models sum local tilt vectors across the measured areal grid to derive true surface area. Steep peak slopes increase the total interfacial area far more than low frequency waviness. Micro-textured polypropylene parts show elevated values that promote mechanical adhesion during secondary coating operations.

Flame treatment increases surface energy without altering the underlying geometric Sdr metric.

Adhesion Enhancement

Interfacial area expansion determines mechanical interlocking force between moulded substrates and overmoulded elastomers. High values provide larger contact interfaces for thermal bonding in multi-material medical devices. Regrind resin processing reduces surface fine detail, lowering the measured parameter across critical bond zones.

Molders adjust cavity blasting parameters to achieve specified area ratios without creating demoulding undercuts.

Quality Control

Topographic scanning verifies texture consistency across large mould cavities before production release. Parameter drift indicates abrasive tool wear or polymer residue buildup inside fine cavity micro-structures. Process auditors define upper acceptance limits to prevent excessive part retention during automated ejection cycles.