Computed Tomography
Computerized Tomography or Computed tomography is well known technique in medical field, popularly known by its abbreviation CT scan. CT scan is also used in industry due to its advantages and wide areas of application. In industrial field it is known as Industrial Computerized Tomography (ICT). ICT is used in industries including aerospace, automotive, metrology and defence etc.
Industrial Computerized Tomography (ICT)
Industrial Computerized Tomography (ICT) also called Industrial Computed Tomography is any computer-aided tomographic process, usually X-ray computed imaging, that uses radiation to produce three-dimensional internal and external representations of a scanned object. ICT scanning is used in many areas of industry for internal checkup of components of the object without destroying it.
Some of the key uses for industrial computed tomography scanning are flaw detection, reverse engineering and failure investigation. Industrial imaging includes both non-tomographic radiography and computed tomography. In this article, we will focus on computed tomography only.
Why Computed Tomography is Necessary in Industry?
If a user wants to evaluate, analyze or test the internal and/or external features of a component without destroying the object, computed tomography is used. In industries Computed Tomography is generally necessary during different manufacturing stages such as in Pre-production, Production, Failure analysis, Lot inspection and Reverse engineering.
Industrial CT scan typically used for
- Assembly analysis
- Material analysis
- Void, cracks and defect detection
- Failure analysis
- Internal and external dimensions measurements
- Non-destructive testing
- Quality Inspection of parts
Types of Scanners
In Industrial Computerized Tomography the imaging is the most important process. To accomplish this, different types of scanners are used. Following types of scanners are used in Industrial Computerized Tomography scanning.
- Fan/Line beam scanner and
- Cone beam scanner
Fan or Line beam scanner in Industrial Computerized Tomography
It is the traditional process of industrial CT scanning. X-ray scanners and employ the use of a beam of X-rays to scan through the volume of the object. The X-ray detector used in line beam scanner is linear. The object is rotated. It takes different 2D images. The data is then reconstructed to create a 3-D representation of the object. Following arrangement shows line beam scanner.
Cone Beam Scanner in Industrial Computerized Tomography
In cone beam scanning, the object to be scanned is placed on a rotary table. Cone beam scanners use a cone beam of X-rays, to take over a large number of 2D images of the object as it is rotated around a fixed axis. These 2D images are collected by the detector. Generally, 2D flat panel X-ray detectors are used to capture the images. These images are then processed to create a 3D reconstruction of the object. Following arrangement shows a cone beam scanner.
Analysis and Inspection Techniques
Industrial Computerized Tomography scan can help to improve the quality of products, both during their development and also when the products are in production.
Various inspection techniques include assembly analysis, Void and defect detection and geometric dimensioning.
Assembly analysis
One of the most recognized forms of analysis using CT is for assembly analysis. CT scanning provides views inside components in their functioning position, without disassembly. Some software programs for industrial CT scanning allow measurements even of hidden part. The ability of CT scanning to provide very accurate measurements of a part is used for research and development.
Void, crack and defect detection
Due to various physical effects metal casting and molded plastic components are typically prone to cracks. Traditionally to find cracks or defects and voids in an object would require destructive testing. CT scanning can detect internal features and defects displaying this information in 3D without destroying the object.
Void analysis can be used to locate, measure and analyze voids inside plastic or metal components. The internal structure of the part can be analysed for cracks, voids or other imperfections that would otherwise go unnoticed. It also provides an easy way to perform wall thickness analysis with extreme accuracy.
Geometric dimensioning
Traditionally, to measure dimensions of any internal part of the object will require destruction of the object. Industrial Computerized Tomography scanning allows for full non-destructive metrology.
With unlimited geometrical complexity, 3D printing allows for complex internal features to be created with no impact on cost. The ability of CT scanning to inspect components without destroying or disassembling them significantly reduces the time needed for companies to undertake analysis and testing.
Advantages of ICT
- The internal structure of the object can be obtained without destroying it.
- Reduced product development time.
- It is compatible with all shapes and sizes.
- It reduces costs relating to the destruction of sample parts during test and analysis.
- Extremely accurate internal dimensions are obtained.
- Comparison with the reference model is possible.
- Post-processing work is not necessary.
Disadvantages of ICT
- Expert handling is necessary to handle CT scan and to remove noise.
- X-rays take longer to pass through materials with higher density, meaning that the CT scan will take more time to complete.
- The radiation from CT scanning may harm to machine operators.
- A potential drawback with CT imaging is the possibility of artifacts in the data. An artifact is anything in the image that does not accurately reflect the true geometry in the part being inspected.
Applications of ICT
- Reverse engineering: Sometimes is a process in which manufactured products are deconstructed to extract design information from them. Often, reverse engineering involves deconstructing individual components of larger products. The reverse engineering process enables you to determine how a part was designed so that it can be recreated. The CT scan is very useful, when a manufactured object is available but design of the object is not available. Using CT scanning an existing part or object is measured and then an exact copy of that object is created. This technology is extremely useful, when a manufactured part or object is available, but not the original prints or design data.
- Wall thickness analysis: Industrial CT scan results can analyse the distribution of material within a part. This can help users in identifying areas prone to weakness.
- Non-contact measurement: The process of capturing the geometry of existing objects through X-ray scanner and a computer software.
- Failure analysis:Industrial CT scan results can be used to evaluate internal failures, such as structural integrity, cracks, deviations from initial design, foreign material and porosity.
- CT scan results can be useful for composite analysis, part to part analysis, and part to CAD analysis.
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