In the production of industrial components, even the smallest deviations can have serious consequences, such as a reduction in quality, safety risks, increased costs and loss of time. Target/actual comparisons ensure that the component meets the requirements and make deviations from the original data visible.

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Optical metrology for digitising components

How is a nominal/actual comparison carried out?

The nominal/actual comparison is carried out on the basis of data and points recorded using optical measurement technology, computer tomography or industrial measurement technology. These measurement methods enable the non-destructive and non-contact measurement of the component to be analyzed, including the rapid measurement of its internal structures. This data is then compared with the target data. The deviations between the component (actual state) and the target state are then visualized. This can be implemented using CAD models, for example. The deviations are made visible and intuitively assessable by means of false color representation and all geometries are recorded on a surface basis.



The deviations correspond to the vertical distance between the target contour (CAD) and the actual contour (STL data from CT or ATOS). A nominal/actual comparison makes the relevant deviations immediately apparent and the necessary countermeasures can be taken promptly. Finally, the deviations must be analyzed for their causes: these are often design errors, manufacturing errors or material defects. This avoids unnecessary follow-up costs due to additional correction loops. The nominal/actual comparison serves as a basis for improving the manufacturing process.

Stereo camera system for high-resolution, digital 3D models

Quality Analysis – The right partner for nominal/actual comparisons

We can also provide you with precise nominal/actual comparisons at short notice. We have both modern computer tomographs and high-quality optical measurement technology systems for creating the most precise 3D models of your component. State-of-the-art software solutions are used to evaluate the collected data and deliver results that you can completely trust.

Fast and reliable


  • Evaluation e.g. against target data (CAD data)
  • Data basis: 3D models from CT, optical or tactile measurement technology
  • High-precision analysis of deviations
  • Clear visualization through false colour display
  • Trend analysis

Why is nominal/actual comparison so important?

The use of precise nominal/actual comparisons offers significant advantages for quality assurance and process optimization. By comparing the surface profile of a test piece with its target state, all deviations from the tolerances can be determined and thus detected and corrected at an early stage. This identification of production deviations can sustainably reduce rejects and rework, which in turn leads to considerable cost savings. In industries where precision and reliability are of fundamental importance, nominal/actual comparison is therefore essential to maintain high quality standards. Companies that invest in this inspection method therefore benefit from increased competitiveness.

False colour comparison: Visualization of deviations

Nominal/actual comparison of components using false color comparison

The data collected using industrial computed tomography or optical 3D measurement technology can be used for numerous other applications, such as damage analysis or checking shape and position tolerances As can be seen in this example, the visualization clearly shows where the component has too much or too little material. Blue indicates a lack of material, while red areas have excess material; in the green areas, the actual state corresponds to the target value.

Areas of application of the nominal/actual comparison

The nominal/actual comparison is particularly important in industries such as the automotive, aerospace, medical technology and manufacturing sectors, where high precision and quality are crucial.



The non-destructive analysis of complex internal and external geometries of components and assemblies is an indispensable element of quality control in the automotive sector. Here, nominal/actual comparison is used, for example, as a comprehensive surface analysis of components to check that the component geometries match the CAD specifications. This method, supported by technologies such as 3D scanning, enables precise detection of deviations across the entire surface of the component.


Plastics industry:


Ever tighter tolerances in plastic injection moulding require continuous process optimization and strict quality controls in order to remain competitive. Nominal/actual comparisons are essential to ensure the accuracy of injection moldings and plastic components. This method allows a precise check and shows whether the actual geometries of injection molded parts or other plastic components match the specified CAD models. This precise analysis of the entire surface is essential for quality control and process optimization, especially in the case of plastics where changes such as shrinkage and deformation can occur during production.


Medical technology:


In order to ensure maximum precision and safety in medical devices and implants, nominal/actual comparison is used in medical technology. The exact conformity of instruments and components with their design specifications is crucial to ensure surgical accuracy and the functionality of medical devices. Nominal/actual comparison allows manufacturers to identify and correct deviations in manufacturing, helping to prevent complications during medical procedures. In a field where any micrometer deviation can have serious consequences, this method plays a crucial role in ensuring compliance with strict regulatory requirements and safeguarding patient well-being


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Peter Mohl


+49 7022 2796-622