Non-destructive testing (NDT) is a testing or evaluation method used to inspect materials, components, or structures without damaging or altering them. NDT techniques can be used to detect surface or subsurface defects, measure properties such as thickness or hardness, or identify the presence of foreign materials or flaws.
While computed tomography has taken its rightful place as a powerful technology for non-destructive testing in quality assurance and quality control, manufacturers have increasingly discovered its capabilities as a process improvement tool. During R&D, computed tomography enables engineers to collect valuable information about the quality of 3D printed products and to feed this information back into the production loop for a continuous improvement of AM processes – reducing cost, risk, and lead time.
Nominal-actual comparison and GD&T
A CT dataset contains all geometric data of the inside and outside structures of a sample. So, the actual geometry of a part can be easily compared with a CAD file, providing a color-coded model of geometric deviations. It is also possible to conduct geometric dimension and tolerance (GD&T) checks on the real part data.
In addition to nominal-actual comparisons between scan data and CAD file, CT also measures internal and external features in three dimensions. All measurable features with their respective tolerance can be defined using the CAD model to create a measurement template, which can be applied to the actual dataset by the click of a button.
Porosity and defect analysis
Since computed tomography uses X-rays to inspect the part, delamination, pores, loose powder, cracks, and many other internal defects can be visualized and analyzed. The appropriate software displays pores in color code , while the pore size distribution can be plotted to a histogram or scatter plot.
Mechanical simulation (on "real" data)
For a first assessment of the structural integrity of a given part, finite element (FE) stress simulations can be performed directly on CT scan data. This procedure is particularly suitable for highly complex structures such as foams, lattice structures, or components with microporosity.