In hydropower, and in the power generation industry as a whole, precision engineering is critical for efficiency and reliability. At one project last year in South America, in a beautiful region surrounded with volcanoes, we utilized advanced reverse engineering techniques, combining 3D scanning and high-precision measurement tools, to precisely determine the necessary dimensions for refurbishing a hydropower turbine’s lower guide bearing fit, and correct a vibration issue.
Assessment of the Bearing and Shaft Condition
During the initial inspection, we found significant damage to the lower bearing contact surface and the shaft itself. Visual inspections revealed substantial wear and scoring, necessitating a detailed dimensional analysis to determine appropriate corrective actions.
Precision Measurement and 3D Scanning
Our team employed meticulous physical measurements using precision micrometers and gauges, carefully recording multiple data points around the circumference of the shaft and bearing.
Simultaneously, we conducted a comprehensive 3D scanning of the shaft to precisely quantify its roundness and the extent of wear. The scanner provided a detailed digital map, offering a clear visualization of deviations and informing our engineering decisions.
Dimensional Analysis and Fit Optimization
The data collected from physical measurements and 3D scans were carefully analyzed against standards (ANSI B4.1-1967). Our analysis indicated discrepancies from ideal fit conditions, notably the shaft and bearing clearances, which were found to be excessively tight, likely contributing to inadequate hydrodynamic lubrication.
Bearing Machining Recommendations
Given the condition of the shaft, we opted to precisely machine the bearing to ensure optimal clearances. Using fit standards referenced from the Machinery’s Handbook, we determined the appropriate dimensions, recommending a final bearing inner diameter machining tolerance of 430.06 mm ±0.02 mm to achieve ideal hydrodynamic lubrication.
Material Considerations for the Bearing Surface
The chosen bearing surface material was a Babbitt alloy, closely aligned with ASTM B23 Grade 11 specifications. This material choice was based on its excellent antifriction properties and proven suitability in high-load, hydrodynamic applications.
Final Quality Control and Results
Post-machining, the bearing dimensions were verified on-site using 3D scanning and an internal diameter micrometer, to ensure they matched specified tolerances. Our quality control processes confirmed the machining accuracy was within ±0.03 mm, fully complying with the recommended tolerances and ensuring optimal bearing performance.
The bearing was installed following the recommended procedure. During the test runs and subsequently during normal operations, the vibrations were measured and recorded. They behaved in the normal expected range, improving significatively when compared with the condition before the intervention.
Through advanced reverse engineering, combining traditional precision measurement tools with modern 3D scanning technology, we accurately identified, analyzed, and resolved critical issues related to the bearing fit. This meticulous approach has significantly improved the reliability and operational longevity of hydropower turbine components, exemplifying our commitment to excellence in engineering precision.
