You have a component, but no design documentation. Or the existing documentation no longer matches the actual part, because changes have been made over the years that were never documented. An industrial plant is being dismantled and rebuilt at another site, but the CAD data for key components is missing. A spare part is needed, but the manufacturer no longer exists.
Reverse engineering using a 3D scanner solves precisely these problems: the physical object is scanned, the scan data is converted into a digital model, and this is used to create a CAD data set for reproduction, documentation or further development. This allows physical objects to be converted into digital models: precisely, completely and reproducibly. But which 3D scanner is the right one, and when is a surface scan not sufficient?
No CAD? No manufacturer? Here’s how to get your data anyway.
In industrial practice, there are often situations where a physical component exists but the digital data is missing. The most common reasons for reverse engineering and 3D scanning:
- No design documentation available: The CAD data has been lost, is out of date, or was never created. Old machines, components manufactured by hand, or products from manufacturers that no longer exist. The part is there, but the digital information is missing.
- The documentation does not match the component: Over the years, changes have been made that were never documented. The drawing says A, the part says B. For reproduction or retrofitting, you need the current condition, not the intended condition from 15 years ago.
- Retrofitting and plant relocation: An industrial plant is dismantled and rebuilt at a different site. Pipework, housings and brackets must be recorded accurately, reflecting their actual condition, not as described in the files.
- A spare part is needed, but the manufacturer no longer exists: A worn-out gear, a broken housing, a cast part that is no longer available. The only reference is the physical object itself.
- Product development based on an existing part: An existing product needs to be optimised or a new prototype developed. The quickest way: scan, create a digital replica and edit it in CAD, rather than
In all these cases, reverse engineering using 3D scanning provides the foundation: a precise digital data set that accurately replicates the physical object. This enables reproduction, documentation or further development, even without existing design documentation.
Which 3D scanners are suitable for reverse engineering?
There are various types of 3D scanners available for reverse engineering. Each device has its strengths and limitations. The right choice depends on the object, the accuracy requirements and whether internal structures also need to be captured.
Optical 3D scanners (strip light, laser)
Optical 3D scanners use structured light or lasers to capture the visible surface of an object. They are particularly well suited to free-form surfaces, organic shapes and design objects. The accuracy is typically between 0.02 and 0.1 mm.
Strengths: Fast scanning of large surfaces, high detail resolution in visible areas, relatively inexpensive to purchase.
Limitations: Internal structures, undercuts and hidden areas cannot be captured. Glossy, transparent or dark surfaces often require pre-treatment (matting). For complex assemblies, multiple scans from different angles are required, which must be merged manually or automatically. Missing areas occur wherever there is no line of sight.
Industrial computed tomography (CT)
Industrial CT scans the entire object with X-rays and generates a complete 3D volume model. Unlike optical 3D scanners, CT also captures internal geometries, cavities, channels and hidden features. All in a single scan, without the need for disassembly.
Advantages: Complete capture of internal and external geometry, non-destructive, no surface pre-treatment required, a single data set for all features. In addition to geometry, CT also enables the analysis of material defects such as porosity or inclusions. The precision of modern CT systems reaches values of less than 10 micrometres.
Limitations: Limited by material density, component size and material composition. Materials that are difficult to penetrate, such as thick-walled steel, or components with significant variations in wall thickness can cause artefacts. The scanning time is longer than with optical methods, but there is no need for post-processing of missing areas.
Tactile coordinate measuring machines (CMMs)
Tactile measuring devices scan individual points on the surface. They offer the highest accuracy (up to 0.001 mm), but do not capture volumetric data and are too slow for the spatial capture of complex free-form surfaces. In reverse engineering, they are therefore primarily used for targeted re-measurement of critical dimensions, rather than as the main scanner.
Advantages: The highest accuracy of any method, traceable to national standards, regardless of surface finish. Ideal for validating individual dimensions following a 3D scan.
Limitations: Very slow with many measurement points; no surface data; no volume data. Not suitable for the complete capture of a component as the basis for a CAD model. Useful as a supplement, not as the sole data source.
Tactile, optical or CT: Which 3D scanner should you choose for reverse engineering?
Choosing the right process is not a question of ‘better or worse’, but depends on the component and the task at hand. Each process has clear strengths and clear limitations:
| Criterion | Tactile (CMM) | Optical 3D Scanner | Industrial CT |
|---|---|---|---|
| Capture | Individual points on the surface | Visible surface as point cloud | Volume: interior and exterior |
| Internal Geometries | Only with direct access, very limited | Not capturable | Fully capturable |
| Assembled Assemblies | Disassembly usually required | Disassembly required (line of sight) | Scanning in assembled state possible |
| Surface | Uncritical, as long as probeable | Critical (glossy/transparent) | Mostly uncritical |
| Missing Areas | Unmeasured points are missing | Common with undercuts | None, since volumetric |
| Accuracy | up to 0.001 mm | 0.02 to 0.1 mm | 0.015 to 0.05 mm |
| Speed | Slow with many features | Fast for surfaces | Longer, but everything in one scan |
| Suitability for Freeform Surfaces | Barely suitable (too few points) | Very well suited | Very well suited |
| Data Basis for CAD | Individual measurements, no surface data | Surface model | Complete volume model |
The reverse engineering process: from 3D scan to CAD model
Step 1: Scanning and data capture
The physical object is scanned. With optical 3D scanners, scans are taken from various angles and then stitched together. With CT, the component is captured in a single pass, including all internal geometries. In both cases, the result is a point cloud: a cloud of millions of individual 3D points that describes the object’s spatial geometry.
Step 2: Data preparation and STL mesh model
The physical object is scanned. With optical 3D scanners, scans are taken from various angles and then stitched together. With CT, the component is captured in a single pass, including all internal geometries. In both cases, the result is a point cloud: a cloud of millions of individual 3D points that describes the object’s spatial geometry.
Step 3: Surface reconstruction
The real challenge in reverse engineering: parametric surfaces are extracted from the triangular mesh, which can then be edited, dimensioned and used for manufacturing in CAD software. Depending on the component, two approaches are used:
Automatic surface reconstruction: The software automatically recognises basic geometric shapes (planes, cylinders, cones, curves) and generates parametric elements. Suitable for prismatic components with clear geometries. The speed of this approach significantly accelerates the process.
Design-based reconstruction: An experienced engineer manually remodels the component in CAD software, using the scan data as a reference. This is required for complex free-form surfaces, organic shapes, or when a ‘clean’ parametric model with a feature tree is to be designed. This approach facilitates subsequent changes to the design.
Step 4: Create and export the CAD model
The finished CAD model is exported in the desired format, such as STEP, IGES or a native format (SolidWorks, CATIA, Siemens NX, Autodesk Inventor). The file can be imported directly into existing CAD tools and used for production, simulation or optimisation. A final comparison of the model against the original scan data ensures that the model corresponds to the physical object.
Practical examples: When is CT-based reverse engineering worthwhile?
Case 1: Retrofitting of an industrial plant. The documentation is no longer up to date.
A production facility is to be relocated to a new site. Although old drawings exist for several housing and connecting components, these no longer reflect the current state of affairs because changes have been made over the years that were never documented. A 3D optical scanner captures the external geometry, but the wall thicknesses, internal channels and sealing surfaces remain invisible. CT-based reverse engineering solves this: the component is fully captured in its current state, inside and out. The result is CAD data that reflects the actual current state and serves as the basis for remanufacturing and reconstruction at the new site.
Case 2: Reproduction of a component without existing CAD data
A turbocharger housing with internal flow channels is to be remanufactured. The manufacturer no longer exists, and no CAD data is available. The relevant features (channel cross-sections, wall thicknesses, transitions) are located entirely inside the object. None of these are visible from the outside or can be captured by an optical 3D scanner. Dismantling the component would damage sealing surfaces and fits. The CT scan generates a complete 3D volume model, an engineer carries out the reverse engineering of the surfaces, and the component can be digitally reconstructed: with all internal geometries, non-destructively and without dismantling.
Reverse Engineering at Microvista: Process and Services
Microvista offers reverse engineering as a service for components with complex internal geometries. Our industrial CT systems can scan objects with a maximum outer diameter of 715 mm and a length of up to 1600 mm. We can also process materials that are difficult to penetrate, such as iron, steel or dense alloys.
Every project begins with a consultation: we clarify your application, the required file formats, tolerances and whether automatic or constructive surface reconstruction is appropriate. This is followed by the workflow described above, from the CT scan to the finished CAD model.
Delivery options:
- Scan data only (point cloud / STL)
- STL mesh model (for 3D printing / visualisation)
- Complete parametric CAD model (for manufacturing / design)
Depending on the complexity, the turnaround time ranges from a few days to two weeks. For companies without their own CT facilities, this service provides access to high-resolution 3D scanning without the need to invest in their own equipment.
Frequently asked questions about reverse engineering using 3D scanning
That depends on the component. For objects with purely external geometry and accessible surfaces, an optical 3D scanner is often sufficient. However, when internal structures, hidden features or assembled components need to be captured, industrial CT is the more suitable method. We can help you choose the right option.
That is exactly what reverse engineering is for. We scan your existing component using CT, capture all the geometries – including the internal ones – and provide you with a CAD model for reproduction, documentation or further development. Existing drawings are not required.
Yes, that is one of the most common applications. When an industrial plant is dismantled and rebuilt at a different site, the existing documentation often no longer matches the current state of the plant. 3D scanning captures the actual condition and provides the data needed for reconstruction, including all changes that have never been documented over the years.
The achievable accuracy depends on the scanning technology and the size of the component. Optical 3D scanners achieve 0.02 to 0.1 mm, whilst industrial CT scanners achieve 0.015 to 0.05 mm. For prototype manufacturing, 0.1 mm is usually sufficient. For fits and functionally critical dimensions, a combination of scanning and targeted re-measurement is recommended. The precision of the scan alone does not guarantee an accurate CAD model. The quality of the surface reconstruction is equally crucial.
The cost depends on the size of the component, its complexity and the scope of delivery. A simple CT scan with STL output is significantly cheaper than a full reverse engineering process resulting in a parametric CAD model. Please contact us for a personalised quote.
Not every application. CT has limitations when dealing with very large or extremely dense components. Our systems can scan objects with a maximum outer diameter of 715 mm and a length of 1600 mm, weighing up to 200 kg. Materials such as aluminium, plastic and light metals are ideal. Heavy metals such as steel also work, but require a corresponding tube power. For purely external geometries, an optical device may be more efficient.
Depending on your requirements: STL mesh models, STEP, IGES or native CAD formats. The data can be imported directly into your existing CAD environment.