Why investing in X-ray inspection systems pays off Detect foreign objects or monitor fill levels: X-ray inspection systems are suitable for many applications in industry.

A Rontgen inspection system consists of the three core components generator, detector and image processing as well as mechanics and conveyor technology. Special hardware configurations are available for different areas of application, enabling the core components to be used in a wide variety of applications.

Structure of a generator

In their simplest form, modern X-ray tubes consist of the following components:

• Glass envelope

• Heating cathode

• Copper anode

• Tungsten disc

All components lie within a vacuum in a sealed glass or ceramic body. The heating cathode serves as the electron source and consists of a tungsten filament that is made to glow by an electric current.

By applying a high voltage (kV) between the copper anode and the heating cathode, electrons are accelerated and move towards the tungsten disc. The electron current at this point is called the X-ray tube current (mA). When the electrons hit the tungsten disc, they are slowed down considerably. This deceleration causes the emission of X-rays. In an X-ray generator

the tube is shielded with lead or copper. The usable X-rays leave the generator through a small opening (see red waves in the graphic).

The generation of usable X-ray radiation releases heat and makes it necessary to cool the generator. Therefore, the X-ray generator is often located in a housing that is filled with a cooling liquid such as oil. The dissipation of heat is often enhanced by cooling fins. The cooling requirement results from the power of the generator and the ambient temperature.

Generally speaking:

• for X-ray detectors from 65W to 100W, simple fans are sufficient for circulating the warm air

• Powerful air conditioners are used for units from 100W to 320W output.

• for high power detectors with 1000W and more, a pump system with active water cooling is required.

X-ray inspection looks for foreign bodies that absorb a higher amount of radiation than the product being inspected. Reliable detection of foreign bodies is therefore only possible if they have a comparatively higher density.

Many foods are water-based or based on water due to their natural structure, such as fruit and vegetables. Thus, they have a similar density to water (1000 kg / m3). In terms of specific gravity, this corresponds to a value of 1.0 g / cm3. This value is usually used as a reference point.

The following table illustrates the detectability of material types. Materials marked in red cannot normally be detected because their density is too low or almost the same as that of the product. Materials marked in green can be detected due to their higher density. The table is sorted in descending order of density. The higher a material is in the table, the higher the attenuation factor and thus these elements are better detected in the food. This also means that smaller particles can also be detected more easily.

Caution: When defining detection sensitivities for the quality management system, the density of the materials that pose a risk according to the risk analysis should also be specified. For example, not all glass is the same: lead glass, for example, has a density of 3.5 - 4.8 g / cm3. In contrast, soda-lime glass (also called soda-lime-silica glass, the most common material for glass containers such as

bottles or glass jars) have a density of 2.52 g / cm3. It is obvious that the absolute detection sensitivity of these two types of glass differs greatly. Therefore, care must be taken that for the definition of search sensitivities of an X-ray inspection device exactly those materials are evaluated which actually exist as a risk in the production environment.