The University of Birmingham has recently invested in Nikon Micro CT equipment, which has been installed in the School of Metallurgy and Materials and was partly funded through an ERDF project called CHART.
Computed Tomography, or CT for short, is more generally familiar to an audience who have seen the equipment used in a medical environment, such as a CAT scanner.
Micro CT uses the same technology but is designed to examine objects at a smaller scale. The technique takes a series of digitally captured high definition X-rays while an object is being rotated. This produces several thousand flat standard x-ray images that are similar to those that have been used in medicine for decades.
X-rays reveals the internal structure of an object by interacting with different densities of material: higher density parts look lighter on the image than less dense areas. These 2D images are then combined and processed by computer software, utilising a mathematical technique, to produce a 3D representation of the image. This image not only reveals surface detail but also internal structure.
Micro CT is an ideal complimentary technique for both reverse engineering and additive manufacturing (3D Printing). To demonstrate how Micro CT technology works, to an audience of school children, we chose a Kinder Egg (a well-known chocolate egg that has a plastic toy hidden inside).
The idea was to demonstrate that it is possible, and sometimes desirable, to scan and measure an object that has multiple layers that are hidden from view, and to rebuild (reverse engineer) that object in a computer model. This 3D computer model can then be used to manufacture a reproduction of the original object by utilising a 3D printer.
The overall goal was to give a conceptual idea of the process – Scan and Print – to encourage the audience to consider how these techniques may be used in a useful way. (For example, an interesting development in recent years has seen the process being used for hip replacements. In this way a more exact replacement can be made to fit the patient). The process follows the same route: CT scan, computer modelling, then 3D printing in powdered Titanium.