Optical offline inspection system detects color deviations of plastic pellets

Optical offline inspection…

Sikora offers in addition to control and sorting technologies optical inspection systems for sample inspection of plastic pellets. The Purity Concept V inspects automatically small amounts of pellets and is therefore used for quality assurance in incoming goods inspection, production control and follow-up inspection. The system detects reliably contamination such as black specks. As the Purity Concept V (V = visual) is equipped with a color camera, color deviations of the pellets are detected as well.

For sample inspection and analysis with the Purity Concept V, up to 3,000 pellets (100 g), placed on a sample tray, are being moved through the inspection area. Within seconds, a camera inspects the material, contaminated pellets are detected and analyzed. The detected contamination is highlighted in color on the monitor image as well as on the sample tray.

The Purity Concept V contains a CMOS line color camera with a resolution of 50 µm. In combination with a long-life white LED light, it enables the recording of a high-resolution image of the inspected sample material. 

Picture 1. Display of the recorded sample material with marked color deviations

In addition to “classic” black specks, smallest color deviations are also detected. For this, adaptive detection algorithms analyze the inspected material. For example, color deviations due to cross contamination are optionally displayed and evaluated on the monitor (picture 1). This way, the operator receives besides the information about number, area and size also findings about the color spectrum of the inspected sample.

Picture 2. Distribution of detected color deviations and color assignment

Within the inspected sample, the saturation and the color value distribution of the detected deviations are clearly displayed in a diagram (picture 2). Due to the visualization in a common scatter plot, the distance of the saturation and the color value of the contamination to the good material is clearly to see (picture 3).

Picture 3. Scatter plot for displaying the color saturation and color shade of color deviations

The adjustment to specific requirements, like e. g. the detection sensitivity, is done by the operator by choosing the recipe parameters. This allows, for example, to focus on dark or black contamination while simultaneously small and grey contamination can be hidden.

Therefore, the Purity Concept V offers a reliable sample inspection with regard to the detection of black specks, identifies color deviations and enables their exact allocation and analysis. Furthermore, the system provides a test certificate with all information about the inspected pellets as well as a summarization of the test results. Thus, it provides the prerequisite for material release and delivery to the customer.

Source: Sikora

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