EuroWire January 2020

Technology News

Automated inspection and analysis of plastic pellets

EVEN the smallest metallic contamination in plastic pellets can cause problems during the production and processing of plastics. Fault prevention usually requires major effort, but fault correction is time-consuming and expensive. High-voltage cables have to be coated with a 100 per cent metal-free plastic insulator. Metal contamination of a submarine cable can cause breakdown (short circuit), leading to very high recovery and repair costs. There are many causes of metal contamination in raw material, such as abrasion both of the metal screws in the extruder and of the barrel. Abrasion can also occur at conveyer pipes and pipe bends. Metal contamination can get into the pellets due to damaged melt filters or a defective granulator. Full protection against metal contamination cannot be ensured, even with the use of melt filters, inductive metal separators or permanent magnets. www.candorsweden.com • Electrolytic plating • Candojet hot water cleaning • Electrolytic & Ultrasonic degreasing • Welding wire cleaning and copper coating • Pickling & phosphating

▲ ▲ The X-ray-based inspection and analysis system detects metallic contamination in plastic pellets

a batch can be taken at different times and scanned for analysis. The measuring values are included in the overall evaluation. The collected data provides information about the process and the material quality of the plastic pellets. The system also supplies a test certificate containing all information about the quality of the inspected pellets and a summary of the test results.

Sikora AG has developed an offline inspection system that detects and analyses contamination from 50µm in plastic pellets. With the support of X-ray technology, a non-destructive look into and through plastic pellets is possible. Materials such as pellets and metal particles can be differentiated as they vary in their absorption or attenuation of X-rays, and even the smallest metal inclusions in the raw material can be detected.

The inspection and analysis system can be connected to a company network via LAN interface, and collected data can be exported for processing. The creation of a central and up-to-date data bank allows for conclusions on sources and causes of contamination.

The X-ray unit is hermetically sealed, so no radiation can escape and the standards of the Radiation Protection Act and Radiation Protection Ordinance are fulfilled, and the system can be used by the operator without any concern. The operator places the material onto a 210 x 300mm sample tray; this is moved through the inspection area, which features an X-ray camera, and the inspection and analysis are carried out within 30 seconds. A projector

The mobile system can be used for sampling inspection in a laboratory environment or alternatively directly next to the production line. In addition to traditional production control, the 30-second analysis procedure makes the system suitable for the inspection of incoming goods. The system can inspect pellets, flakes, films/tapes, sheets and injection-moulded parts made from various plastics, such as XLPE used for the insulation of high-voltage cables, TPU or TPE. The height of the test material can be up to 50mm. 100g of plastic pellets can be inspected and analysed per run. With a pellet size of 4 x 4 x 4mm, this corresponds to up to 3,500 pellets. Sikora AG www.sikora.net

Welding wire copper coating

▲ ▲ Metal

inclusions in plastic pellets, caused by a damaged extruder during material production

highlights contaminated material in colour directly on the sample tray. The contamination is simultaneously visualised and highlighted on the monitor, including information about its size and area. In addition to an image gallery of detected contamination, the software provides statistics about size, area and number. Previously recorded image material can be re-imported and evaluated, for example with divergent analysis parameters. In addition to single inspections, serial tests can be performed – any number of samples from

Multi wire cleaning plant

Ultrasonic & Electrolytic

CANDOR Sweden AB Tel: +46 11 21 75 00 Fax: +46 11 12 63 12 Email: info@candorsweden.com

52

www.read-eurowire.com

January 2020