Tribological Study on Tailored-Formed Axial Bearing Washers

Abstract

To enhance tribological contacts under cyclic load, high performance materials are required. Utilizing the same high-strength material for the whole machine element is not resource-efficient. In order to manufacture machine elements with extended functionality and specific properties, a combination of different materials can be used in a single component for a more efficient material utilization. By combining different joining techniques with subsequent forming, multi-material or tailored components can be manufactured. To reduce material costs and energy consumption during the component service life, a less expensive lightweight material should be used for regions remote from the highly stressed zones. The scope is not only to obtain the desired shape and dimensions for the finishing process, but also to improve properties like the bond strength between different materials and the microscopic structure of the material. The multi-material approach can be applied to all components requiring different properties in separate component regions such as shafts, bearings or bushes. The current study exemplarily presents the process route for the production of an axial bearing washer by means of tailored forming technology. The bearing washers were chosen to fit axial roller bearings (type 81212). The manufacturing process starts with the laser wire cladding of a hard facing made of martensitic chromium silicon steel (1.4718) on a base substrate of S235 (1.0038) steel. Subsequently, the bearing washers are forged. After finishing, the surfaces of the bearing washers were tested in thrust bearings on an FE-8 test rig. The operational test of the bearings consists in a run-in phase at 250 rpm. A bearing failure is determined by a condition monitoring system. Before and after this, the bearings were inspected by optical and ultrasonic microscopy in order to examine whether the bond of the coat is resistant against rolling contact fatigue. The feasibility of the approach could be proven by endurance test. The joining zone was able to withstand the rolling contact stresses and the bearing failed due to material-induced fatigue with high cycle stability.

Manufacturing and Evaluation of Multi-Material Axial-Bearing Washers by Tailored Forming

“…This effect of grain refinement is intended to further optimize the mechanical properties of the component. Fatigue tests at component level for tailored forming machine elements were conducted in earlier work [7]. The subsequent forming process showed an improvement in bearing fatigue life for different tailored forming components by improving the joining zone quality.…”

“…The test was carried out with lubricating oil at 70 • C and 250 rpm (cf. [7]). To stabilize the bearing temperature, the test head was cooled by convection.…”

Investigations on Tailored Forming of AISI 52100 as Rolling Bearing Raceway

“…First, a hybrid bearing washer with AISI 52100 cladding was tested on the FE8 test rig with 40 kN at 250 min −1 (p H = 1.85 GPa, κ = 0.55), in accordance with previous investigations [13,14]. In these investigations, maximum running times until failure of 260 h for a cladding with a martensitic chromium-silicon steel (AISI HNV3, 1.4718), and 332 h for a cladding with AISI 5140, were achieved.…”

“…They employed a test matrix that utilized the variations of process parameters to influence the geometry and microstructure of the materials' joining zone. Pape et al [13] investigated the manufacturability of multimaterial components by combining the high-alloy steel AISI HNV3 (1.4718) with the base substrate of ASTM A283 (1.0038) in a single component. The materials were joined by laser metal deposition by wire according to the stressed zones of the component and examined.…”

“…The force was applied by a disc spring assembly in axial direction and measured by a HBM C2 load cell (Hottinger Baldwin Messtechnik GmbH, Darmstadt, Germany) during mounting. For an initial functional test, the test parameters from previous tests with other cladding materials were applied [13,14]. Here, the axial load was 40 kN.…”