CT Measures The Impossible

As experts for initial sample inspection, the team at 3DIMETIK , Kassel, Germany handles all sorts of plastic parts that at first appear to be impossible to measure – at least without first breaking them down into several pieces.

“We are commissioned to perform measuring tasks for injection-molded parts to which there is literally ‘more than meets the eye’: some can be just a few centimeters in size but still have complex interior structures and challenging shapes. If your task as a service provider is to digitize this, conventional measuring equipment will soon be at its limits,” says Pascal Mohr. “Let’s take a concrete example from the medical industry: cannulas are a part of hospital routine. But they give measurement engineers a headache. The cannulas have very small openings, which need to be accurately measured. Only a measuring device with high resolution is capable of achieving this. At the same time, there are deep convolutions into which I have to look with the measuring device in order to obtain all geometry information, while the measuring device must be capable of coping with the transparent material of the cannula. Looking at these requirements together, both CMMs and fringe projection scanners are unsuitable for measuring. Only by using computed tomography can a complete digital image be produced in a nondestructive way.” 

GOM CT Delivers Razor-Sharp Images

But not all CTs are the same, says Pascal Mohr. He picks up a transparent part, which is closed with a small green lid and is about 1 x 1 cm in size. “On the lid alone, we have 200 inspection positions in an extremely confined area. Customers expect us to provide them with a precise metrological evaluation – and I can only offer this if I record the measurement data with a very high-resolution computed tomography system. The CT needs to see things that are invisible to the naked eye.”

According to Mohr, the GOM CT is leading the field in this respect. The system uses a 3k X-ray detector (resolution: 3008 x 2515 pixels) with an extremely fine pixel grid (pixel size 100 µm). This results in razor-sharp images showing the part in finest detail. Mohr adds that even with complex geometries, the measurement data set is 100 percent closed. “More than once we have received calls from delighted customers who wanted to find out how we managed this nondestructively. The 3D models generated from the measurement data exceed expectations.” The experienced measurement engineer adds that he currently knows of no system that produces better STLs for small plastic parts than the GOM CT.

For more information: www.gom.com