A Proposition for New Quality 3D Indexes to Measure Surface Roughness

The average absolute roughness Sa presented in ISO 25178, commonly used in the industry, is not a reliable discriminator of different surface texture types. This paper presents new quality indexes for a 3D characterization of surface texture of diamond cut die inserts used for injected plastic optics in lighting applications. The proposed surface quality indexes, namely floor and ceiling surface quality index (FSQI, CSQI) were tested on nineteen different die insert samples. The results of the analysis demonstrate that FSQI and CSQI provide a better understanding and improved discriminator of the texture of different high precision diamond cutting processes than Sa.