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B Pearson Forum Presentation Scrubbed


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Technical presentation at Cymer Inc. of my vibration research on spinning shaft. Investigate route causes including wind effects. Defined experimental setup, present findings and implications, propose further investigations.

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B Pearson Forum Presentation Scrubbed

  1. 1. XLX Vibration Testing Brandy Pearson 8/28/2007
  2. 2. Overview: XLX <ul><li>New product for flat panel processing </li></ul><ul><li>Key Specs: divergence, pointing, energy stability </li></ul><ul><li>Differences from XLA: </li></ul><ul><ul><li>Heavier fan, 550kPa pressurized chamber vs. 350kPa, 5500rpm blower speed vs. 3500rpm, 3.7kW motors </li></ul></ul><ul><ul><li>Higher power 1200W vs. 90W </li></ul></ul>Free Side Example of chamber lower cross-section <ul><li>Extra space with preload </li></ul><ul><li>to allow for thermal expansion </li></ul>
  3. 3. Sideview of Chamber <ul><li>Two relevant cutoffs that induce pressure differential forces against blades. </li></ul>FAN Anode Support Bar (ASB) Lower Cutoff
  4. 4. Interesting FFT Components <ul><li>1xblowerspeed & 2xblowerspeed, 3x, 4x, 5x… </li></ul><ul><ul><li>Primarily mechanical sources: </li></ul></ul><ul><ul><ul><li>Mechanical looseness, misalignment </li></ul></ul></ul><ul><ul><ul><li>Mass unbalance </li></ul></ul></ul><ul><ul><ul><ul><li>Bent shaft, large overhung rotors </li></ul></ul></ul></ul><ul><ul><li>Expected to be more pronounced than XLA design due to heavier fan, higher speeds and pressure forces </li></ul></ul><ul><li>Bearing Ball Pass Frequencies 3.05x, 4.14x, 4.95x: </li></ul><ul><ul><li>Pronounced peaks at these frequencies indicate inadequate/defective bearings: </li></ul></ul><ul><ul><ul><li>outer ring ~3x, inner ring ~5x </li></ul></ul></ul><ul><ul><ul><li>ball spin freq ~4x </li></ul></ul></ul><ul><li>23x & 46x Components: </li></ul><ul><ul><li>The blade pass frequency (BPF) & 2*BPF </li></ul></ul><ul><ul><li>Any one point sees 23 blades per revolution </li></ul></ul><ul><ul><li>Aerodynamic sources: induced by pressure fluctuations as blades move past: </li></ul></ul><ul><ul><ul><li>Lower cutoff </li></ul></ul></ul><ul><ul><ul><li>ASB </li></ul></ul></ul>FFT Spectrum
  5. 5. Minimizing Divergence/Pointing <ul><li>Interested in minimizing divergence </li></ul><ul><ul><li>FFT vibration spectra correlated with divergence spectra </li></ul></ul><ul><ul><li>Interested in avoiding low frequencies, which drive mechanical resonances & natural frequencies on optics table & mounts </li></ul></ul>
  6. 6. The Test Plan <ul><li>Open lower with Design1 fan (s/n 1655 00013) </li></ul><ul><li>-forward, 3500 to 5500rpm in 250rpm steps </li></ul><ul><li>Forward fan sweeps 3500 to 5500rpm, 100rpm steps for the following: </li></ul><ul><li>Open lower with Design2 (s/n 1655 00012) </li></ul><ul><li>Sealed pressurized chamber @ 550kPa with Design2 , no ASB </li></ul><ul><li>Sealed unpressurized chamber with Design2 , with ASB </li></ul><ul><li>-forward and backward , 3500 to 5500rpm,100rpm steps </li></ul><ul><li>Item above pressurized @ 550kPa </li></ul><ul><li>Open lower with Design1 fan (s/n 1655 00009) </li></ul><ul><li>Sealed pressurized @ 550kPa with Design1 (s/n 1655 00009) with ASB </li></ul><ul><li>Open lower with Design1 fan (s/n 1655 00013) </li></ul>
  7. 7. Setup <ul><li>TD401 chamber </li></ul><ul><li>12mm bearings </li></ul><ul><li>3.7kW motors </li></ul><ul><li>Design1 & Design2 fans </li></ul><ul><li>HXers installed </li></ul><ul><li>Triple decker test stand </li></ul><ul><li>2 single axis accelerometers 100mv/g </li></ul><ul><li>ZonicBook </li></ul><ul><ul><li>Linear avg over 30sec </li></ul></ul><ul><ul><li>Create FFT spectra 0 to 5000Hz </li></ul></ul>
  8. 8. Thermal Effects <ul><li>Measurement sweeps from 3500rpm to 5500rpm in 100rpm steps </li></ul><ul><li>Vibration data acquired & avgd for 30 sec </li></ul><ul><li>To check repeatability repeated sweeps x4 </li></ul><ul><li>Saw consistent vibration increase over the 4 runs due to heating of bearing and spindle assembly </li></ul><ul><ul><li>Installed HXers and plumbing to water cool the system…trend disappeared </li></ul></ul>
  9. 9. Dominant Gas Effects <ul><li>Gas effects are present even in an open lower </li></ul><ul><li>23x & 46x peaks at least as relevant as 1x & 2x </li></ul>46X 23X FFT
  10. 10. Sealed, Pressurized, Fan Design2, ASB: Forward vs. Backward <ul><li>Verifying gas effects by observing FFT peaks up to 54x. </li></ul><ul><li>Run fan backward for minimal gas flow </li></ul><ul><li>Fan balanced to 0.008 mm/s clamped side, 0.015 mm/s free side </li></ul>Dominant 46x peaks Low harmonics with high vibration -mechanical looseness Observe dominant 46x peaks running forward fan. No 23x or 46x peaks running backwards. Gas effects demonstrated to be caused by fan blade pass.
  11. 11. Sealed, Fan Design2, ASB: Unpressurized vs. Pressurized <ul><li>Verifying gas effects by tracking overall integrated vibration, 23x and 46x peaks </li></ul><ul><li>Overall vibration increases with pressurized chamber as expected. </li></ul><ul><li>23x and 46x peaks increase due to increased aerodynamic forces </li></ul>
  12. 12. Sealed, Pressurized Design2 Fan: ASB vs. NO ASB lower 46X component large 23x contributor Investigating the effect of the ASB as an additional cutoff. <ul><li>The 23x component spikes are reflected in the integrated vibration curves, indicating a large contribution to overall vibration. </li></ul><ul><li>If 46x is found as a large source of divergence the ASB could be redesigned </li></ul>
  13. 13. Open Lower: Fan Design2 vs. Fan Design1 Trial1 Fan Design2 Fan Design1 (s/n 1655 00013) *250rpm step CLAMPED SIDE Fan Design1 demonstrated much lower overall and gas induced vibration- low 23x and 46x components. <ul><li>Installed a Design1 Fan. </li></ul><ul><li>Balanced to 0.077mm/s clamped side, 0.034mm/s free side. </li></ul>
  14. 14. Open Lower: Fan Design2 vs. Fan Design1 Trial1 Fan Design2 Fan Design1 (s/n 1655 00013) 46X resonance lower 23X & overall total vibration *250rpm step FREE SIDE Double chevron, free side also demonstrates lower overall vibration levels and 23x.
  15. 15. Open Lower Double Chevron: Trial1 vs. Trial2 Trial1 Trial2 larger integrated vibration low 23X <ul><li>Installed another Design1 fan with different s/n to verify repeatability. </li></ul><ul><li>Balanced to 0.019mm/s clamped side, 0.015mm/s free side. </li></ul>The overall integrated vibration increased for Trial2. Since 23x and 46x peaks appear comparable, seems that vibration increase due to mechanical sources not gas effects. 46X resonance
  16. 16. Open Lower Fan Design1: Trial 1 vs. Trial 3 Trial 1 *250rpm step <ul><li>46x resonance structure and low 23x components are consistent. </li></ul><ul><li>Low overall/integrated vibration not reproducible for 5000rpm +. </li></ul><ul><li>Reinstalled initial Design1 fan again to check for repeatability. </li></ul><ul><li>Balanced to 0.014mm/s clamped side, 0.005mm/s free side. </li></ul>Trial 3
  17. 17. Sealed, Pressurized Chamber with ASB: Design2 fan vs. Design1 fan lower 23X component <ul><li>Design2 & Design1 at 550kPa to determine if 23x and overall vibration remained lower under pressure. </li></ul><ul><li>Design1 Fan demonstrated comparable overall vibration. </li></ul><ul><li>23x component remained lower in pressurized conditions. </li></ul>
  18. 18. Conclusions <ul><li>Gas effects are significant contributors to chamber vibration </li></ul><ul><li>Design1 fan reduces 23x even at 550kPa </li></ul><ul><li>To minimize 23x & 46x components: </li></ul><ul><ul><li>Run sealed chamber with Design1 without ASB to observe if 46x component becomes minimized- redesign of ASB could be beneficial </li></ul></ul><ul><ul><li>Test fan with slanted blade design that may reduce pressure fluctuations along cutoffs </li></ul></ul><ul><li>To reduce mechanical vibration: </li></ul><ul><ul><li>Investigate thermal effects: bearing assembly shown to be loose at temps low as 50 °C </li></ul></ul><ul><ul><li>Consider larger bearings to support larger loads in the XLX design </li></ul></ul><ul><ul><li>Tighter tolerances </li></ul></ul><ul><ul><li>Improved fan balance </li></ul></ul>
  19. 19. Lessons Learned <ul><li>How to analyze data using Igor software… compiling & running procedure files </li></ul><ul><li>The value of exporting and processing data efficiently </li></ul><ul><li>Look & verify data as you collect it </li></ul><ul><li>Write as much as possible down in the lab notebook </li></ul>