Manufacturing and testing of a tyred wheel with casted ADI wheel centre

Although the foundry practice of cast iron is well established, manufacturing a wheel with this material requires a careful choice of casting parameters in order to produce defect-free castings suitable for the assembly of a railway wheelset. In this paper, both the manufacturing and the testing phases of an innovative wheel centre made of Austempered Cast Iron (ADI) are described. The full qualification of a new wheel requires a long testing process, whose fundamental steps are the assessment of the material properties and of the fatigue resistance of the wheel. The papers discusses also other properties measured during testing, such as the vibration (damping) behaviour of the wheel centre as well as complete noise characterization including line tests. In the frame of the activities for the development of a lightweight and quiet wheel centre for the class ALn668 DMU belonging to the fleet of the railway enterprise TRENORD, the use of Austempered Ductile Iron (ADI) castings was considered. Structural design strength and numerical validation of the wheel centre are shown in another paper give to this conference [1]. Fundamental part of the project was the development of a dovetail (tapered) tyre / wheel centre coupling in order to avoid the use of the retaining ring while keeping safety margins of the traditional (and very expensive from a maintenance point of view) solution [2]. Manufacturing a wheel requires a strong control on all phases, from iron composition to casting, from visual tests to RT and UT tests. The paper describes manufacturing, destructive and non-destructive testing with the relevant results. This paper reports on the comprehensive testing plan, to achieve a complete analysis of the in-service behaviour of a vehicle equipped with casted ADI wheel centres. As it is clear that safety plays the most important role in service, material testing and full-scale testing of a wheel centre will be described first. Nevertheless, other properties of the wheel centres and of the vehicle will be assessed, namely the vibroacoustic properties of the wheel centre obtained with laboratory tests and noise emissions measured during pass-by tests of a vehicle equipped of this innovative solution. The new wheel centre (130 kg) allows a mass reduction of 50 kg with respect to the original steel wheel centre (180 kg).