Industrial CT measurement technology for quality inspection

Nowadays, quality testing is one of the most important tasks of companies that manufacture products for industry. It guarantees that the products meet customer requirements and fulfill their intended purpose 100%.

What is industrial CT measurement technology? Industrial computed tomography enables the non-destructive testing of components and assemblies. It enables the measurement and material analysis of parts for quality inspection.

In industrial CT measurement technology, components are scanned with a high-performance X-ray beam and a large number of X-ray images are taken. These make it possible to create CAD models with which the components can be compared with 3D data. Differences that are outside the defined tolerances can thus be identified reliably and accurately.

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Advantages of industrial CT measurement technology vs. optical and mechanical measurement technologies

In modern quality inspection, components are tested for various requirements in order to guarantee their function. Quality testing is particularly critical for safety-relevant components. They must be checked carefully, as production errors can have fatal consequences.

In most cases, the quality requirements of the components are precisely specified by customers. The quality department must then decide how the customer's requirements can be monitored, guaranteed and documented. For many components, it is sufficient to carry out optical or mechanical measurements in order to guarantee the dimensional accuracy of the components.

However, if the quality requirements are very high, normal measuring techniques can quickly reach their limits. This is particularly the case when it comes to safety-relevant components on whose function human lives depend. This can be the case in the automotive industry, the aviation industry and the aerospace industry, among others. It is then in the interest of the companies to use measuring techniques that guarantee 100% dimensional accuracy and the corresponding material requirements. Traditional measuring techniques quickly reach their natural limits.
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Mechanical measuring techniques

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Mechanical measuring techniques include measuring methods such as calipers and gauges. Micrometers and measuring systems with mechanical scanning are also referred to as mechanical measuring devices. They can be used in quality inspection to monitor the dimensional accuracy of components.

Which mechanical measuring techniques are used depends on the customer's requirements. The decisive factor is the tolerance specified for the components. While calipers can only be used to check tolerances of +- 0.1 mm, modern multi-sensor measuring devices can be used to take digital measurements, some of which can detect tolerances of several hundredths of a millimeter.

Material tests and dimensions inside the components cannot be checked with mechanical measuring devices!

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Optical measuring devices

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Optical measuring devices use optical sensors or laser beams to measure components. In contrast to mechanical measuring devices, they can detect tolerances of less than 1 µm. In contrast to mechanical measuring devices, the measurements are taken without contact with the component being measured. The advantage of optical measuring devices lies primarily in their accuracy. As the components do not have to be scanned by a sensor for the measurement, measurement inaccuracies are also eliminated.

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Industrial CT measurement technology

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Industrial computed tomography is used as a measurement technique when conventional measurement techniques do not provide the required accuracy or components and assemblies are too complicated. This can be the case, for example, with dimensional data for assemblies whose components have to be checked individually but which cannot be dismantled for the measurements. Industrial measurement technology also offers the possibility of using computer tomography to check material inclusions that can lead to qualitative problems in the component.

Industrial computed tomography is now an established procedure in the

quality assurance, with which production and processes can be reliably monitored. Industrial CT measurement technology also offers the option of digitally capturing components and complete assemblies. In contrast to tactile measurement techniques, which quickly reach their limits, industrial CT measurement technology can capture complex component structures and intricate component geometries and enables digital assessment.

The 3D volume models created using industrial CT measurement technology can be evaluated for their component properties, both in terms of the outer skin and the internal structures. It also offers the possibility of finding defects such as air inclusions, porous areas, cracks or blowholes, which represent qualitative problems. Even fiber courses can be made visible with industrial computed tomography.

Another advantage of computer tomography is the inspection of complete assemblies, which can be used to check the accuracy of fit of the individual components. An assessment of the assembly condition can be made without having to dismantle the assemblies.

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Reverse engineering with industrial CT measurement technology

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The non-destructive measurement of components using industrial CT measurement technology makes it possible to create complex 3D volume models that can be used to produce plans for reproduction. As computed tomography can also be used to carry out wall thickness analyses inside components and assemblies, exact plans can be produced for reproduction.

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Direct comparison of components

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Another advantage of industrial CT measurement technology is the ability to directly compare two or more components. This makes it possible to identify differences that may occur during industrial production. For example, products manufactured at the beginning of a batch, in the middle of a production batch and at the end of production can be compared. In this way, tolerances in production that can lead to quality problems can be identified.

In industrial CT measurement technology, a distinction must be made between different methods:

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Two-dimensional industrial CT measurement technology

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In two-dimensional industrial CT measurement systems, the object to be measured is not rotated. These systems can measure parts in a single beam path. This measurement technology is best suited for inspecting damaged areas inside components and for recording two-dimensional dimensions.

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Three-dimensional industrial CT measurement technology

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In three-dimensional CT measurement technology, the component to be measured is rotated, enabling the creation of complex 3D models. During the measurement process, the objects to be measured are recorded layer by layer. Data models are created that consist of many different points. They can be converted into 3D models that can be used for precise quality checks .

To create 3D models, computers with high computing power and a lot of storage space are required. Three-dimensional CT measuring systems are more expensive than two-dimensional CT measuring systems due to their more complex technology and higher requirements.

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The industrial Helix CT measurement technology

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Helix CT measurement technology is based on three-dimensional CT measurement technology. However, the component to be measured is also shifted in the longitudinal axis. The X-ray image is constructed in a helical shape (helix). Helix CT measurement technology is particularly suitable for longer components that cannot be measured using other measurement methods.

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Differences due to the size of CT systems

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Systems for industrial CT measurement technology can also be distinguished by their size. The size requirements are determined by the dimensions of the components to be measured and the required measuring accuracy.

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Macro CT measuring systems

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Macro CT measuring systems are manufactured for large components and assemblies. They can X-ray objects with an edge length of several meters. As the measuring accuracy suffers as a result, these systems are mostly used for the quality inspection of complete assemblies. This makes it possible to determine whether all components in the assemblies have been installed correctly. In most cases, high-resolution measurement of individual components is not possible with macro CT measurement technology.

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Micro CT measuring systems

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Micro CT measuring systems are developed for components with a maximum edge length of up to 10 cm. The resolution of these systems is in the micrometer range and is suitable for the precise quality assessment of components. These systems are particularly often used to inspect composite materials. They can identify cracks, inclusions, burrs and blowholes that lead to quality problems.

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Sub-micro CT measuring systems

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Sub-micro CT systems only play a small role in industrial CT measurement technology. They are used to measure very small components and offer a resolution of up to 500 μm. They are mostly used for checking the quality of electronic components or for measuring organic objects.

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Use of industrial CT measurement technology in quality control

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Computed tomography provides important information for the quality control of components that cannot be generated with other measuring techniques. For most companies, however, it is not worth acquiring an industrial CT measuring system, as its use is only suitable for industrial production to a limited extent and the systems are very expensive.

Service providers such as Q-Tech offer the option of measuring components and assemblies using industrial CT measurement technology and incorporating the results into quality monitoring. This allows the quality of the relevant components to be guaranteed or appropriate production changes to be initiated.

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