Despite being a dynamic and complex tool, Computed Tomography’s (CT) usage spans a wide variety of testing abilities – ranging from the inspection of components for both external and internal measurements, through to detection of discrepancies and defects generated during the manufacturing process.
In addition, an essential aspect of CT is that it can also be employed for creating either a drawing or model for reverse engineering purposes.
Reverse engineering is performed for testing and analytical purposes and not necessarily for duplicating the part. It can be employed for transforming physical models to digital ones or replicating worn parts. Although this is a very common process in the industry, it is not necessarily easy.
Challenges
Common challenges facing reverse engineering include many different types of equipment that may not be available, and not having the proper software and personnel to carry out the complex tasks.
The modern day test lab includes multiple teams of Engineers, all with particular tasks to execute during the reverse engineering process. The process becomes quite time intensive when this is coupled with the need for several pieces of equipment to complete the testing.
CT Scanning
With the help of CT, data can be produced quickly to resolve the most complicated and intricate component and assembly designs.
Just like CAT scanning that is employed in the medical field, CT employs different imaging methods to generate data – the only difference is that a considerable number of images are collected by the CT, while the specimen rotates 60°, whereas in CAT scanning the gantry rotates around the specimen.
The images obtained are reconstructed to a 3D volumetric digital model, using the software. The data is then stored as a point cloud set to a number of formats (.PLY, .OBJ, .STL, etc). The process can continue with modeling into another appropriate format such as a parametric CAD model, a set of NURBS surfaces or a triangular mesh.
A windshield wiper motor pump was used in one application by North Star Imaging. In order to optimize resolution, the individual component is CT scanned. 3D pixels or voxels represent the data of the scan. This voxel size is directly correlated to the scan resolution. In other words, the closer the object to the x-ray source and the further the detector (imaging sensor), the better the resolution.
Conclusion
An important factor to consider is that the object still requires 360° of rotation during imaging. With CT software, the collected data is gathered into one workable volume as soon as the component is scanned, and from this volume the software allows the model to be manipulated.
When analyzing the collected data, reference measurements and sections of the part are just some of a few tools at the operator’s disposal. At this stage, surfaces can also be created by simply placing a wire mesh to define the model features.
This information has been sourced, reviewed and adapted from materials provided by North Star Imaging, Inc.
For more information on this source, please visit North Star Imaging, Inc.