Quantifying Surface Elevation Variance along Score Lines Using Optical Profilometry
Optical profilometry quantifies score elevation variance down to sub-micron resolution, identifying die wear and coating micro-fractures before carton assembly.
Focus Variation Metrology
Optical Profiling
Quality control of high-end printed packaging requires precise measurement of surface roughness and coating thickness to ensure consistent gloss and ink adhesion. An optical technique known as focus variation metrology addresses this need by combining the small depth of field of an optical system with vertical scanning to reconstruct a three-dimensional model of the paperboard surface. It allows packaging engineers to analyze the micro-texture of the paper and any protective varnishes applied to it.
This data helps in adjusting coating processes on the manufacturing line.
Surface Assessment
The micro-topology of the board influences how the ink transfers from the plate to the substrate. Utilizing focus variation metrology, technicians can inspect the fiber orientation and coating cracks after folding. This method is effective for measuring rough or structured surfaces that would damage a mechanical stylus.
The optical scan provides high-resolution data that can be used to predict how the surface will interact with adhesives and coatings.
Instrument Function
Measurement sensors operate by moving vertically relative to the specimen while capturing sequential images. Only the sharpest points in each image are used to calculate the height map, which is then translated into roughness parameters like Ra and Rz. This automation speeds up the testing of batches during high-volume production runs.