Optical Profilometry Replica Metrology Protocol for Mould Cavity Topography
Indirect optical profilometry on elastomeric cavity replicas yields sub-micron texture data while eliminating tool teardown and optical access limits.
Peak Height Sz
Meaning
A three-dimensional surface texture parameter measures the absolute vertical distance between the highest peak and the deepest dale within a defined evaluation area. Precision mould auditors measure peak height sz according to ISO 25178 to quantify maximum defect depth and surface roughness extremes on tooling cavities. Average roughness parameters like Sa fail to detect localized surface scratches or isolated pitting defects.
Evaluating this extreme height metric catches tool steel damage before it causes mechanical ejection dragging or cosmetic blemishes on moulded parts.
Roughness Extreme
Calculating spatial peak-to-dale distances involves identifying maximum height excursions across the entire sampled grid. Unlike profile peak height Rz, peak height sz captures localized surface anomalies across an entire areal region. A single deep scratch from abrasive glass filler particles drives up this parameter, alerting quality teams to mold cavity degradation.
Tool Wear
Tool steel erosion from corrosive resin off-gassing increases peak heights over extended manufacturing campaigns. Monitoring peak height sz during preventive maintenance reveals progressive cavity pitting before part ejection fails.
Quality Benchmark
High polish optical tools mandate strict upper limits on maximum surface peak excursions. Specifying peak height sz in tool purchasing contracts guarantees optical lens clarity and prevents part defect acceptance.