Radial forging of aluminum to steel preform for the production of light-weighted wheel bearing outer race

In this research work an innovative procedure through which to manufacture the outer race of vehicles wheels bearing, aiming to reduce their total weight, is proposed. Utilizing the radial forging process, an aluminum workpiece is forged on a steel core, resulting in the same geometry for the wheel bearing outer race but allowing to achieve a considerable weight reduction. By considering the most burdensome load conditions the outer race has to stand, a stress analysis is implemented in ABAQUS/Standard by applying both bolts and bearing ball forces. Based on the stress distribution, the portion of the cross-section where the load is bearable by the aluminum 6061 alloy is identified and a new steel workpiece, realized by removing the above-mentioned volume, is created. The aluminum workpiece is then hot-forged on the steel part, replacing the removed steel volume and recreating the original shape of the bearing outer race, afterwards tested with the same load conditions to verify that the combined forged part is able to withstand the same loads. To optimize the interface behavior between hot-forged Al6061 and 45Cr steel, simple tension test specimens, realized by forging an aluminum workpiece on a steel plate, have been manufactured realizing different surface knurling on the steel plate and by pre-heating the aluminum part at different temperatures. With the proposed approach, the weight of the bearing outer race has been reduced of 35.8% while granting the same mechanical performances of the original component.