ADVANCED MATERIALS & PROCESSES | JULY 2026 30 of the material. In an era where additive manufacturing and surface coatings are central to modern materials development, this surface-first approach provides more relevant data than axial testing, which averages stress across the entire cross-section. WHY RBF IS BETTER: THE GENERALIZED MODEL ADVANTAGE RBF is a generalized model. It does not try to replicate the exact complex loading of a bridge joint or a prosthetic hip. Instead, it provides a pure, clean environment to measure a material’s fundamental endurance limit. This generalization yields several practical benefits, including fast results, accurate alignment, and cost. By operating at 100 Hz, an RBF system can complete that same 107 cycle test in less than 28 hours. What took an axial frame nearly a week can be done in a single day. This allows researchers to run multiple design iterations within a single work week. Another advantage of this model is the use of standard ER32 collets. Unlike axial grips that require painstaking alignment, collet-based RBF systems are self-centering. An operator can swap a specimen in under 60 seconds with total confidence in the alignment, virtually eliminating the variance caused by human error. Perhaps the most compelling argument for RBF systems in 2026 is the price point. A high-quality RBF rig typically costs one-third the price of a mid-range axial fatigue frame. Further- more, the operating costs are significantly lower with no hydraulic infra- structure drawing kilowatts of continuous power or requiring scheduled oil maintenance. WHO SHOULD USE RBF? While RBF systems are powerful, they are tools that must be applied strategically. Users will apply criteria unique to their role when determining whether to use RBF. Materials Researchers: If a researcher’s goal is to understand how a new alloy or a surface coating (like PVD or thermal spray) affects fatigue life, RBF’s sensitivity to surface-initiated cracking makes it an early-warning system for surface-driven fatigue failure. Quality Managers: For those looking to integrate a rapid, high-throughput quality check on the production line, RBF allows for high-volume sampling to ensure that a batch of material meets the minimum endurance specifications before it is shipped. Academic Researchers and Graduate Labs: RBF systems are significantly cheaper to acquire and operate than servo-hydraulic frames, making them accessible to university labs that need to generate S-N curve data for publication without a large capital equipment budget. The simplicity of the specimen geometry also reduces machining costs. Testing Labs: A lab that can deliver fatigue screening results in 28 hours rather than six days can take on more projects, serve more clients, and offer a lower price point without compressing margins. RBF’s minimal fixturing requirements also reduce the per-client setup cost with no specimen-specific grip configurations The four-point loading configuration of the eXpert 9300 ensures a uniform bending moment and highly repeatable results. Looking from the top down into the RBF tester.
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