Optical Profilometry Basics for Hardened Steel Tool Cavity Verification
Optical profilometry non-destructively maps 3D tool cavity topography (Sa, Sz) to verify polished steel finishes and predict injection part ejection forces.
High Dynamic Range Metrology
Meaning
Advanced optical measurement techniques capture both highly reflective and non-reflective surfaces within a single scan by combining multiple exposure levels. This high dynamic range metrology is particularly useful for inspecting complex polymer parts that feature both textured matte finishes and polished gloss areas. It allows quality inspectors to measure critical dimensions without applying anti-reflective sprays.
The technology speeds up the inspection process while preserving the native surface characteristics of the sample.
Surface Scanning
Traditional optical scanners often struggle with surface variations, leading to data loss or inaccurate points. When using high dynamic range metrology, the scanner takes successive images of the moulded part at varying light intensities. This method captures the geometry of both dark, recessing pockets and bright, raised surfaces on the tool or part.
The software then merges these images to reconstruct a complete three-dimensional point cloud of the component. This point cloud is then compared to the nominal computer-aided design model to verify dimensional compliance.
Exposure Optimization
Balancing the light levels during scanning requires specialized algorithms that analyze the sensor’s saturation limits. In high dynamic range metrology, the camera sensor avoids overexposure on specular highlights while ensuring that shadow regions receive sufficient illumination. This optimization is necessary for measuring complex injection-moulded parts that have sharp internal radii or deep ribs.
Improper exposure settings can mask surface defects or yield false measurements of critical tolerances.
Quality Auditing
Accurate verification of dimensional consistency across multiple production batches is the foundation of quality assurance. Integrating high dynamic range metrology into the audit routine reduces the risk of shipping defective parts. The high-resolution data provides a clear record of part dimensions over time.
This data is invaluable for tracing dimensional drift caused by tool wear.