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.
RMS Slope Sdq
Meaning
An areal surface texture parameter calculates the root mean square of local surface gradients across a measured topography grid. Metrology software determines rms slope sdq to evaluate surface sharpness and micro-texture slope distribution on moulded plastic surfaces. Flat surfaces produce values near zero, while steep micro-roughness peak structures yield significantly higher numerical values.
Tool steel EDM spark erosion finishes create distinctive slope signatures that dictate coating adhesion and mold release forces.
Gradient Calculation
Differential height changes between adjacent pixels form the mathematical basis for calculating local surface slopes in x and y directions. Computing rms slope sdq requires high spatial resolution, as sparse sampling grids smooth out steep micro-features and artificially lower calculated values. Surface inclination readings indicate whether textured plastic interior trims will exhibit unwanted gloss or light scattering properties under ambient illumination.
Surface Wetting
Liquid contact angle and adhesive bonding depend strongly on surface slope steepness and real surface area multipliers. Monitoring rms slope sdq helps quality control verify plasma treatment efficacy on polyolefin substrates prior to printing or structural adhesive bonding.
Tool Texture
Chemical etching of tool steel alters local cavity wall angles, influencing part ejection friction during tool stripping. Tracking rms slope sdq across cavity surfaces identifies tool wear before scuffing defects occur on ejected parts.