Measurement of the visual perceptibility of sink marks on injection molding parts by a new fast processing model

The aim of this work is to present a novel methodology for fast evaluation of the visual perceptibility of sink marks on surfaces of injection molded parts. Based on previous research work on the detection of surface defects, a new model for the calculation of the visibility of sink marks from CCD-images was developed. A new calculated surface model function was used to determine the amplitudes of the second derivatives (ASD) as a measure for the visual perceptibility of sink marks. This model parameter is quickly calculable and, therefore, ideally suited to application in a machine vision system used for in-line quality inspection. In order to test the model parameter, injection molding parts were produced using predefined processing conditions, and the influence of process parameter variation on the visual perceptibility of the sink marks was evaluated.