TPT September 2019

AR T I C L E

Sikora AG

The inspection takes place automatically and within seconds: a projector marks contaminated material directly on the sample tray. Simultaneously, it is displayed and marked on the monitor, including information on size and area of the contamination (figure 1). By analysing the images, contamination like black specks starting from 50 μm (2 mil) and discolourations are automati- cally detected, visualised and analysed in transparent as well as coloured or diffuse material. As an alternative to optical technology, a system with X-ray technology is available for the detection of metallic contamination inside as well as on the surface of non-transparent, coloured and transparent plastic materials. Individual contaminated pellets can be selected and zoomed in. At the same time, they are optically visualised on the sample tray by cross hairs (see figure 2). A clear allocation of the contamination and follow-up inspection are always possible and permit new insights regarding the production process. The presented optical inspection and analysis system contains specially developed analysis software for the detection, visualisation and evaluation of contamination. The software includes an image gallery of detected contamination as well as statistics regarding their size, area and number. Furthermore, previously recorded image material can be imported for follow-up analysis. The inspection and analysis system can be integrated into the company network via a LAN interface in order to export and process collected data. The data provides the users with comprehensive information about the process and the material quality. For example, by establishing a central and constantly updating database, conclusions regarding sources and causes of contamination are possible. On this basis, existing processes in the company or at suppliers can be optimised to ensure comprehensive quality control. Statistical evaluation and storage of the measuring values

Figure 1: Detected contaminants are marked and selected pellets are highlighted in colour and zoomed in

Figure 2: Detected contamination is highlighted in colour. Pellets that are selected on the monitor are visualised on the sample tray by cross hairs

Application areas of the automatic light table

The described automatic light table offers a broad range of applications. Flakes, micro granulates, films as well as extruded and injection moulded parts with a sample height of up to 5mm (0.2") can be inspected on the sample tray, which has a width of 295 x 210mm (11.6 x 8.3") (see figures 3 to 5). For instance, approximately 100g (0.22lb) pellets can be inspected and analysed per run. This corresponds to up to 3,300 pellets with a size of 4 x 4 x 4mm (0.16 x 0.16 x 0.16").

Examples of detected

contamination by optical technology:

Figure 3: Discolouration in flakes

Figure 4: Foreign body in film Figure 5: Black speck in pellet

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SEPTEMBER 2019