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Reliability growth method is as a supporting tool for the production readiness plan of a new product line, in order to have an estimated probability of field failures during normal production. This is accomplished in the case study presented herein using prototypes test bench data. Evaluation is carried to verify its adequacy to support new product launch. Additionally, continuous improvement and evaluation of design change impact on product performance is another potential application of the method. In the case study a reliability growth planning and assessment is conducted prior to a new alternator pulley product line launch to confirm initial durability targets of the product could be achieved during transition from R&D validated prototype to the mass production items of the new product line. It includes efforts from Product Engineering during development stages until Start Of Production (SOP).

Alternators usually have a solid pulley to connect it to the Front-End Accessory Drive (FEAD) system. Current stringent emissions regulations and fuel economy push for new alternatives to meet goals such as, for instance, reduced idle speed and engine downsizing. However, achieving these goals could ultimately generate NVH issues, such as belt slip chirp noise, or reduced accessory-drive support bearing life due to the high vibration levels in the FEAD. Furthermore, increased demand for on-board electric/electronics systems are requiring the use of larger alternators, with bigger inertia, becoming an additional source of vibration.

Alternators used to have a solid pulley to connect it to the Front-End Accessory Drive (FEAD) system. Lately, new breakthrough designs have been developed for some applications, as the Overrunning Alternator Pulley (OAP) and the Overrunning Alternator Decoupler (OAD), with the aim to detach the alternator from the FEAD during high speed transients and to reduce the transmission of torsional vibrations from the internal combustion engine to the engine accessories, respectively. The downsizing of the internal combustion engine and its reduced idle speed to improve fuel economy and emissions led to belt slip or creep, increased NVH issues as chirpy noise or bearing reduced life due to the high vibration levels. Besides of that the increased demand for electric/electronics on-board systems led to the use of larger alternators, with bigger inertia, generating even higher vibration levels.