X-Ray Inspection in the Plastics Industry

sesotec0316For years, X-ray inspection systems have been successfully used for the inspection of food, where they reliably find metallic and non-metallic contaminants and also detect and remove defective products.

Why X-ray inspection also offers advantages for the plastics industry

Apart from the food industry, X-ray inspection systems also are of advantage for inspection applications in the plastics industry, e.g. for the detection of glass, stones, or other contaminants in the material flow which cannot be found by standard metal detectors and often are the cause of machine damage. X-ray systems furthermore can be used for the purpose of reliable quality assurance.

A typical application for X-ray scanners in the plastics industry is the inspection of plastic parts not only for contaminants, but also for the detection of unwanted air inclusions or blowholes and other defects such as over-filled or under-filled plastic parts. Several sources of defects can be checked in one X-ray process. The X-raying principle allows inspection inside closed shapes and packages. For users in the plastics industry quality inspection with X-ray technology thus ensures efficient, fast, and economic quality assurance.

Application Examples




Plastic cover with trapped air


Plastic connector with contamination



Completeness check



Feather connection incorrect

How does an X-ray scanner work?

X-rays have a very high energy and are thus able to penetrate solid bodies. The X-rays for “radiographing” are generated by an electrically controlled X-ray tube. A line-shaped detector that measures the arriving radiation and converts it for further processing is positioned above the conveyor belt. Depending on the density of the inspected object the X-rays, when passing through the product, are attenuated to a higher (high density) or lower (low density) degree. The detector converts the remaining radiation into an electrical signal, and differences in the density of the inspected object can thus be represented in an image. The higher the density of a material, the darker its representation on the X-ray image, and vice versa. The image processing software detects the contrast differences in the image, highlights contaminants or missing products, and outputs a corresponding signal.

Are X-ray systems dangerous for operators or for my product?

Definitely not. Basically there are defined limit values for the so-called “local dose rate” to which persons or products may be exposed without having to fear any health effects.

State-of-the-art X-ray systems such as Sesotec’s RAYCON series are equipped with a sophisticated shielding system that reliably keeps generated X-rays inside the machine. Safety devices with multi-channel monitoring and mechanically extended covers ensure that operators never can directly reach into the X-rays. This guarantees that the actual local dose rate is many times lower than the limit values and that the operation of X-ray inspection systems therefore is absolutely safe for the production staff.

For comparison only: During an 8-hour intercontinental flight the body approximately absorbs 34 times the radiation that it absorbs during eight hours of work at a distance of 10 centimetres from an X-ray inspection system. Even the generally existing terrestrial radiation in Germany on average is four times higher than when working near a Sesotec X-ray scanner.

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Sesotec – an overview
The Sesotec group is one of the global leading manufacturers of machines and systems for product inspection and for the sorting of material flows. Product sales primarily focus on the food, plastics, chemical, pharmaceutical, and recycling industries. Sesotec has subsidiaries in Great Britain, France, Italy, China, Singapore, India, Canada, and in the USA, a representative office in Turkey and agencies all over the world.


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