Procedure for determining manufacturing defects in a diesel engine in a workshop

Customers' demands regarding the quality level of automobile vehicles are constantly increasing. These demands include noise, vibration and harshness (NVH) quality as an important item. The main source of NVH in the vehicle is the engine and this is particularly the case for diesel engines. The design effort to reduce the emissions of noise and vibration transmitted to the vehicle's driver could be lessened because of the assembly process variation and assembly errors. In the present paper, a procedure for assessing these variations or errors is suggested in order to maintain NVH performances within the limits of the design and achieve the quality level expected by customers. In order to achieve it, the measurement of the engine vibration level through three sensors allocated at strategic points is suggested. Some objective criteria based on the vibration level at certain frequencies are established to determine possible assembly defects as a final step of the assembly process. (C) 2009 Elsevier Ltd. All rights reserved.