What is in this article?:
Computed tomography is transforming non-destructive testing for critical parts, like automotive turbochargers for BorgWarner
- 450-kV X-ray equipment
- Combined NDT for inspection, analysis
- Targeting, Selecting CT Tools
A 2D image of a cast iron turbocharger.
A microfocus computed tomography (CT) system developed by Nikon Metrology is being used by a BorgWarner auto parts plant in southwestern Poland to improve research and development of cast iron turbochargers it produces for passenger cars, light trucks, and commercial vehicles. The 450-kV X-ray equipment penetrates dense materials needed in cast products of this type, allowing the internal structure and quality to be inspected non-destructively.
In addition, dimensional data for specific components is collected more quickly than is possible with a coordinate measuring machine (CMM), both from external and internal dimensions. With Euro 6 emissions regulations taking effect now, aiming to reduce further the level of gases and particulates allowed in vehicle exhaust, manufacturers of engines and their suppliers are deploying more advanced technology in the design and development of air management systems. Their goal is not only to reduce pollution, but also to improve fuel economy and enhance vehicle performance.
BorgWarner has three plants at an industrial campus at Bielsko-Biala, Poland, including the turbocharger plant that was completed in 2009 to produce over 1 million units annually. These are supplied to automakers building gas and diesel engine vehicles across Europe. More recently, a technical center opened on the same campus to support BorgWarner’s turbocharger production with application engineering and design, simulation, testing and validation, as well as material analysis. This development broadened BorgWarner’s engineering and R&D capabilities considerably in Europe.
It is at the technical center that the Nikon Metrology XT H 450 microfocus CT system was installed in February. Lukasz Krawczyk, the team leader and manager of the material laboratory, said, “We buy in our turbocharger parts, ranging in size from aluminum compressor discs to stainless steel or cast iron housings, from a number of different sources.
“Before we put an assembled turbocharger onto an engine emulator for endurance and thermo-mechanical testing, we need to check the quality of the individual components and sub-assemblies. Previously we did this by sectioning sample castings and machined prototypes, and checking them on a CMM.
“But, that meant we were wasting valuable prototype or pre-series components. Additionally, the parts we were testing were representative examples from the same batch, rather than the ones we actually inspected, which were of course destroyed.
“Now we know that the components under test are only the ones we inspected dimensionally and, in the case of castings, for the presence of porosities or inclusions as well,” he said.
Overall, much more information is available to the inspectors than previously, so their analysis can be more rigorous, and the overall cost of quality control is improved because inspected parts can be reused for further tests. Software makes it possible to correlate the inspected volume against a CAD model, or a master sample, either via direct comparison or through geometric dimensioning and tolerancing (GD&T) measurements.