Turbochargers for automotive engines must be free of porosity and inclusions in order to meet the high-performance standards and reduce exhaust gases. A turbocharger assembly usually consists of two parts, a wheel and a housing. The turbine wheel is set within the turbine housing to absorbe energy from the exhaust gases and transmit it mechanically it to a compressor via a shaft.
The turbine wheel may turn at 160,000 to 300,000 rpm. In a spark-ignition engine, exhaust gas temperatures of up to 1,050°C must be endured in the area of the turbine housing. The turbine wheel, a bypass flap and a heat shield may reach similar temperatures.
BorgWarner produces turbochargers at a plant in Poland, and adopted a microfocus computed tomography (CT) system developed by Nikon Metrology to improve its R&D and quality control of cast iron turbochargers 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.