CT technology from WENZEL

How does industrial computed tomography work in detail?

Industrial computed tomography (CT) works in the same way as medical CT using X-rays. During the scanning process, the patient, or the object being measured, is irradiated with X-rays from different angles. Two-dimensional X-ray images are recorded by a flat detector opposite the X-ray source and stored in the memory of a computer.

The main difference between industrial CT and medical CT is that the object is rotated instead of the entire CT system being rotated around the patient. The big advantage here is that an industrial CT system is therefore much more compact. Here, the object to be measured is only placed on a turntable instead of a patient being pushed through the entire CT system.

In both cases, the tomograph acts as a scanner for data acquisition, which digitizes the object being measured. After the CT scan, the measurement result is stored in the computer's memory. The measurement results are two-dimensional images that have been combined (reconstructed) into a three-dimensional image stack. This image stack can now be virtually sliced in any direction using software and the sectional images displayed. These sectional images provide a detailed insight into the interior of the measurement object.

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Do the tomographs need to be supplemented by data analysis software?

Specific software is used to analyze and evaluate data, depending on the application. Which software exactly depends on the respective application. WENZEL supports users with its in-house software. Depending on the application, the WM | PointMaster 4 CT software or the WM | Quartis software can be used individually or as a supplement. In addition, all common software on the market is supported through the use of standard interfaces.

The focus of the WM | PointMaster 4 CT from WENZEL is on CT data visualization and evaluation, while the focus of the WM | Quartis is on the metrological evaluation of form and position tolerances during production. The special feature of the WENZEL software is that any WENZEL software works together with any WENZEL hardware. This enables cross-hardware automation solutions when using WENZEL hardware and software. The advantages of this solution are low training costs and quick familiarization of the user.

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For which applications are they most frequently used?

The use of industrial CT is very diverse. In the field of so-called non-destructive testing of materials, the task of CT is to obtain information about the internal structure of a material. Material analysis is particularly important in order to detect defects in the material of a component at an early stage before they lead to mechanical failure of the component in use. - An enormous gain in safety!

However, detecting and analyzing defects in materials is by no means the only application of CT. Once a more complex component has been assembled from individual parts, further defects can occur in the interaction of the individual parts, which can be detected using CT.

However, this is by no means the end of CT applications. Special CT-machines, which are designed for maximum accuracy, open up further possibilities. The task of metrology in the quality assurance of manufacturing companies is to evaluate the dimensional accuracy of components. Incorrectly produced components can thus be avoided before they are installed in more complex components. This is an extremely important aspect for reducing production costs.

The unique advantage of CT when used in metrology is that, compared to conventional metrology , it can not only capture the accessible surface, but also all areas inside the component. All conventional technologies used in metrology , such as optical or tactile scanners, cannot capture and evaluate areas inside components. For geometrically more complex components, or components that dodge or are made of transparent materials, only CT scanners can practically be used as measuring systems.

Last but not least, such metrological CT systems in combination with other manufacturing technologies open up further and new areas of application. Once the geometry of the component has been digitized in the computer's memory after a CT scan, the data can be fed back into the design using special software. This process is known as "reverse engineering".

For all applications in the field of non-destructive testing, WENZEL uses its in-house software 'WM | PointMaster 4 CT'. Due to its modular structure, the software is often the most flexible solution and is also very easy to use. There are modules focusing on CT data evaluation and visualization, as well as inclusion/void analysis. WM | PointMaster allows both the processing of triangulated point clouds and the processing of CAD data. In the module for metrology , target/actual/comparison with false color display can be carried out. The same applies to wall thickness analysis or dimensioning. Modules for reverse engineering of CT data and compensation of shrinkage and warpage for molds in the casting sector or in additive manufacturing round off the software functionality.

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Are there radiation sources other than X-rays for tomography?

In addition to X-rays, neutron beams or gamma rays can also be used for tomography. However, the latter are only occasionally used in industrial applications when extremely dense or very large measurement objects are involved.

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What types of objects or materials can be examined?

Industrial tomography can examine a variety of objects and materials, including metals, plastics, ceramics, composites and more. The size, weight and material are critical to resolution and penetration. Components of lower densities are preferred in that they can be scanned very quickly and with good quality.

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What types of defects can be detected and how does the technology differentiate between them?

Tomographs can detect porosity, cracks, inhomogeneities, inclusions and foreign bodies. The technology distinguishes defects based on their density, shape and position in the material. The materials can be distinguished from each other by their gray scale or brightness. Denser areas are imaged brighter than less dense areas.

Why choose this method instead of another non-destructive testing method, such as X-ray testing or ultrasonic testing?

Compared to other non-destructive testing methods such as 2D X-ray inspection or ultrasonic testing, tomography offers a complete 3D representation of the measurement result with the differentiation of materials. This allows the inspection of complex component geometries using the methods and software of coordinate metrology. No other non-destructive inspection method can offer this.

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Can tomographs guarantee inspection rates that are compatible with the production rates of the parts?

The CT systems from WENZEL can achieve high inspection rates that are compatible with production rates. In certain applications, for components with low densities, e.g. in the plastics sector, series/production can be measured at the same rate. The cycle time for the CT scan is in the range of a few minutes, the cycle time per part is a few seconds. Pallet systems for customer-specific requirements in terms of part throughput are individually tailored.

The software solution from WENZEL allows all CT systems from WENZEL to be used for process monitoring during production. A major advantage for companies with products in the medical sector should be particularly emphasized. WENZEL supports medical product manufacturers by certifying the software for process monitoring in accordance with the US FDA ("Food and Drug Administration") regulations.

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What does WENZEL offer in this area?

The WENZEL Group GmbH & Co. KG, a long-standing manufacturer of high-precision tactile coordinate measuring machines and fast optical scanners, offers metrologically calibrated industrial X-ray computed tomography systems. The various WENZEL exaCT models were developed precisely for this purpose. All exaCT models are characterized by the highest X-ray performance on the smallest footprint and impress with their simple and safe operation. There is a solution to suit every requirement, from the exaCT S table-top unit to the exaCT U universal unit with 300 kV.

The exaCT S table-top model is an easy-to-operate microfocus CT device equipped with a long-term stable and high-resolution X-ray source. It impresses with the highest resolution of around 3.5 µm, a metrological calibration capability with an accuracy, MPEE, of 6.9 µm and an impressive X-ray output of 130 kV. Without the need for secondary connections such as water or compressed air, the device can be used wherever conventional CTs are simply too large and too heavy, for smaller measurement objects or in confined spaces. Cost-effective operation with one-year maintenance intervals rounds off the advantages of the device.

In the area of medium-sized exaCT systems, the flexibly configurable exaCT M and exaCT L models allow configurations for X-ray tubes with 150 kV for high resolution or 225 kV for high power. The exaCT L 150 microfocus system achieves resolutions in the range of a few micrometers between 3.5 µm and 4 µm. The exaCT M 225 and the exaCT L 225 impress with their extremely high X-ray performance of up to 225 kV and 1600 W. The systems are complemented by a range of fast detectors up to 3k resolution.

The exCT U universal device can be equipped with either 225 kV or 300 kV microfocus X-ray tubes. The model series can be calibrated in accordance with ISO 10360 / VDI2670 and not only achieves resolutions in the lower micrometer range, but also a calibrated accuracy in the MPEE range of around 10 µm. Different high-resolution or fast 4k/3k detectors are available on customer request. The exaCT U is also available with two doors for fast loading and unloading.

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