CT scanning is a term most often associated with the medical industry, and while it can be used to provide insight to patient anatomy and illness, it can be used for so much more. In this article, we’ll discuss what CT scanning is, how it works, its pros and cons, its applications, and some alternatives to CT scanning. For clarity and simplicity, this article only refers to CT scanning as it relates to industrial applications.
What is CT Scanning?
Computed Tomography, or CT, is a non-destructive 3D scanning method that takes both internal and external measurements by using X-ray emission to penetrate the material of the part being scanned. The resulting X-rays are 2D slices of the part, which are then compiled one on top of the other to create a digital 3D model.
In order for the 3D scan to be completed accurately and safely, the part to be scanned is placed on a rotational platform inside a sealed chamber that will contain the X-ray radiation. An X-ray tube, or emitter, projects either an X-ray line or cone that passes through the part. On the other side of the part is an X-ray detector that records data from the X-ray emission. To get a complete image of the part, the platform the object rests upon will rotate for the X-rays to be passed through the object at different angles. Ideally, the part should be scanned from a full 360°. Measurements are taken at intervals varying from 1° down to 0.1°, meaning about 360-3600 X-rays will be taken to complete the scan. The scanning interval you choose will depend on the resolution you desire for the scan.
Because CT scanning uses X-rays, it has a unique advantage over other 3D scanning technologies. As opposed to optical or touch probe scanners that can only measure surfaces visible to them, CT scanning can provide measurements of internal or hidden geometry without the dismantling or destruction of the part. Furthermore, being able to take complete 2D slice scans with each pass of the X-ray means that you will typically avoid complicated fixtures for setup that other scanning methods often require. CT scanning is also more accurate than its cousins as it can provide point accuracy down to 0.0001”, which far surpasses the capabilities of most other 3D scanners.
Despite its multiple advantages, CT scanning also has several drawbacks that may hinder you. The first and most glaring of these is the cost of a CT scanner. Because this technology is more advanced than optical or touch probe scanners, its cost may be many more times that of other 3D scanners. For this reason, it is best to outsource any CT scanning you require.
Other problems may also arise from part size and material. The radiation from CT scanning must be contained within a sealed chamber to prevent harm to machine operators. As such, your part must be able to fit comfortably inside the chamber so it can fully close. Parts bigger than this chamber would require 3D scanning with a different technology that is not restricted to part size. For instance, optical and touch probe scanners can potentially scan any size of part if you have enough time to scan the entire object.
As for material, X-rays take longer to pass through materials with higher density, meaning that the CT scan will take longer to complete. Additionally, it is not recommended to scan metal parts with this technology because metal absorbs X-rays. This absorption will distort the scan’s measurements by creating streaks on the scan where the metal is located. This may greatly lower the accuracy of your scan.
CT Scanning Applications
Although CT scanning is most commonly used in the medical field, it is also used for reverse engineering, dimensional inspection, and many other common 3D scanning applications. However, CT scanning sets itself apart by being able to take internal measurements without destroying the part to do so. This means that the internal structure of the part can be analyzed for cracks, voids, or other imperfections that would otherwise go unnoticed. Additionally, it provides an easy way to perform wall thickness analysis with extreme accuracy.
Alternatives to CT Scanning
If CT scanning is not an option for your part, optical or touch probe scanners may get the job done satisfactorily. It is especially recommended that you turn to these alternate options when seeking to scan simple parts without hidden geometry. This is because while CT scanning will provide you with excellent results, it may be overkill to use this advanced technology when another simpler and likely cheaper option will do just fine.
3D Scanning at 3 Space
Here at 3 Space, we offer many different 3D scanning services, including structured light, laser, touch probe, and CT scanning. If you are unsure which technology will best fit your scanning needs, our engineers are happy to answer any questions you have. For more information, contact us today.