TPT November 2015

Article

Sikora AG

X-ray scanner for pellet, flakes and film inspection and analysis in the compound, masterbatch and recycling industry By Dr C Frank, Sikora AG, Bremen, Germany

In the different processing steps for the production of plastic products, defects may repeatedly occur. This affects the processes of material producers as well as the compound and masterbatch producers, the processing industry, the recyclers and the whole supply chain. Accordingly, it is necessary to control and monitor the quality of the material used before it is further processed. In an industrial process in the plastic manufacturing industry, it is possible to find many different types of possible defects which enter the end product. These different types of defects can have different effects on the final product. Here we can distinguish between visual effects, but also effects on the functions of the end product as described, for example, in the cable or medical industries. Defects can also cause damage to highly sophisticated processing machines such as an extruder or injection moulding machine.

Introduction: Rising quality demands and challenges in the plastic industry For industrial production, highly pure and flawless plastic material is an important quality aspect. Due to the continuously increasing requirements, it is necessary to detect and monitor defects and impurities of decreasing size in plastic and intermediate products. Impurities of 50µm may already cause damage to production systems, such as to the crosshead of the extruder, or to the end products, with high follow-up costs. An example can be taken from the cable industry. For the production of a high-voltage subsea cable, it is of crucial importance to use highly, or so-called super clean, material. A contamination which enters the cable during production can lead to a massive failure [1] of the cable once it is positioned very deep under the sea level. It costs millions to repair a broken subsea cable. For the cable industry, it is especially important to detect metallic contaminations before the material is used for final production. Therefore, latest norms and standards, such as the Chinese standard IEC 62067 (for 150-500kV) for high voltage cables, demand the exclusion of contamination from 75µm in the processed material [2] . However, not only the cable industry has these requirements. Other industries, such as the medical, hose and tube or car industries, have to monitor and analyse the quality of their used material. The quality standards in the plastic manufacturing industries are permanently increasing. Therefore, plastic material has to be inspected and analysed for different types of defects before it enters the final product. Contamination, defects or inhomogeneities down to a size of 50µm in the material have to be detected. This is achieved by a modular X-ray scanner and analysis equipment that can either be used continuously “at-line” or for sample testing. In this way, transparent, opaque, coloured or black pellets and flakes as well as thick coloured films and tapes can reliably be inspected and analysed. Consequently, highest material purity and stable production processes can be assured.

Picture 1: The X-ray analysis shows two contaminants within a round pellet

Picture 2: Different pellet type is visible due to higher X-ray attenuation

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N ovember 2015