DFMA analysis of front axle assembly of an excavator

Abstract

The front axle assembly of a hydraulic excavator consists of front axle, stub axle and thrust bearing. The front axle carries the weight of the front part of the vehicle, as well as to facilitate steering and to absorb shocks due to road surface conditions. In addition, it absorbs torque applied on it due to the braking of vehicle. It is constructed with I-section in center and the ends are made either circular or elliptical. Stub axles are connected to the front axle by king pins. Front wheels are mounted on stub axle’s arrangement for steering. A nominal assembly gap in the front axle assembly has to be maintained for better performance and for easy maneuvering of the vehicle during operation. The gap depends on the model and the assembly dimensions of the front axle, stub axle and thrust bearing. A typical value ranging from 0.1 and 0.5mm is required for one particular model being manufactured by the local industry. It is reported that there are more number of assembly rejections in maintaining the said gap which lead to higher cost and downtime due to rework or interchange of parts. To reduce this, DFMA analysis was carried out using the concept of stack up tolerance to reduce the rejections and improve the performance of front axle assembly, without affecting the manufacturing.