Meaning
Height parameters evaluate the vertical distance between the absolute maximum peak height and the absolute maximum valley depth within a measured area. Moulding engineers specify Sz to determine maximum peak-to-valley profile extent on tool cavities and plastic parts. High Sz values highlight isolated surface flaws, severe machining scratches or localized material inclusions.
Datasheet average roughness numbers obscure these extreme height outliers because local mathematical averaging smooths peak values.
Extreme Height
Calculation routines identify the single highest peak point and deepest valley point across the complete areal dataset. Unlike profile peak metrics, three-dimensional evaluation captures isolated localized defects across the entire spatial surface. Tool steel micro-cracking and EDM recast inclusions generate sharp height extremes that register clearly in Sz values.
Polycarbonate optical components require low total height values to prevent light scattering.
Quality Inspection
Topographic mapping isolates localized tool damage before aesthetic surface defects transfer onto moulded parts. High peak extremes on core pins create mechanical interlocks that cause part tearing during automated ejection. Process control limits track maximum height growth over production runs to signal abrasive resin wear.
Regrind content increases particulate contamination, generating raised surface bumps on thin-walled parts.
Data Sensitivity
Measurement noise and optical reflection artifacts create false extreme height peaks on shiny polymer surfaces. Robust filtering procedures remove single-point optical spikes before computing final parameter values. Instrument calibration checks vertical range accuracy using step height standards before recording part measurements.
