Surface inspection for safety glasses

To ensure that safety glasses meet the required quality standards, it is necessary to examine their surfaces. The lenses of the safety glasses are transparent and without filters. The goggle blanks are produced in a plastic press and fitted with a sprue holder. Then, the glasses pass trough several stations to finish the surface.

The glasses are positioned and inspected individually in front of a 2D camera. The parts are placed in a fixed position under the camera. The aim is to detect defects such as streaks, black dots and air inclusions. The surface defects are identified using a method called „deflectometry“. Here, sinusoidal stripes are projected from above at a 90° angle, out of phase in the X and Y directions, onto the surface of the glasses via a monitor. The 2D camera records these projections on the lens. The evaluation is carried out using the aku.visionManager® software. Rule-based and deep learning algorithms are combined to achieve precise results. The saturation and brightness values (beta and gamma) are displayed in the HMI.

In this way, the defects to be tested can be detected on and in the surface of the safety spectacles. The output of the phase difference image also allows to display the flow direction oft the finishing.

Our customer can therefore ensure that the quality of the glasses remains at a very high level and even the smallest surface defects with a size of 0.1 mm are detected. Thanks to the machine vision-based system and the aku.visionManager® software, a time-saving and cost-efficient inspection can be carried out.