ISO 25178 Surface Parameters for Injection Moulding Optical Components
ISO 25178 areal parameters define 3D optical surface texture to control stray light and guide injection moulding process windows for precision lenses.
S-Filter Cutoff
Meaning
A wavelength limit in areal surface metrology removes high-frequency noise and micro-roughness from raw texture data. The s-filter cutoff defines the short-wavelength boundary for the surface roughness measurement, filtering out features smaller than the scale of interest. In polymer injection molding, this filter isolates the structural finish of the tool from instrument noise or molecular-level polymer irregularities.
Noise Elimination
Applying the correct s-filter cutoff prevents electronic or optical artifacts from distorting the calculated surface parameters. This digital filter ensures that only the relevant topographical features of the molded part are evaluated. Without this step, high-frequency instrument noise would falsely inflate the measured roughness, leading to incorrect quality assessments.
Texture Measurement
Characterization of textured polymer surfaces, such as grain patterns on automotive dashboards, relies on consistent filtering. The s-filter cutoff is selected based on the manufacturing process and the spacing of the surface features. Using a standardized cutoff allows for comparable measurements across different laboratories and production sites.
This uniformity is crucial when comparing parts molded from different resins or sourcing tools from multiple toolmakers. This ensures that a part produced in one facility matches the texture of a mating part molded elsewhere.
Mold Durability
Evaluation of tool wear during production requires the use of a consistent s-filter cutoff. This focus allows metrologists to track the erosion of the tool texture over time. It ensures that the wear is detected before it affects the aesthetic quality of the molded parts.