Measuring a Plastic Part

The process for measuring a workpiece using a TomoScope® is shown in Figure 44. The measured object is located on the rotary table. During the tomography process, many 2-D radiographic images are taken. The part rotates once through 360 degrees. The 3-D voxel image is available as an intermediate result, which can be used for 2-D slice analyses or embedded material and air void inspections and similar tasks. The measurement points obtained from the voxel data are geometrically corrected using the “autocorrection” feature and compared to the CAD model. Deviations are shown graphically in various colors. In addition, features such as lengths, angles, diameters, and position tolerances are evaluated.

Fig. 44: Measurement example: a) Measured object (Photo); b) 2-D radiographic image; c) Section through voxel volume; d) Point clouds generated by tomography; e) CAD model; f) Colored deviation image.

The measurement process described above is particularly cost-effective, for example, for first piece inspection of plastic molded parts. Inspections that previously required several days to verify multicavity molds are reduced to a few hours. The measurement results can be imported directly to generate corrected CAD data for mold rework by using the “Mold Correction” function in the WinWerth® software. Similar advantages result for sample measurement inspections. The same method can also be used in a similar form for other materials and production processes.