Inspection for Texture and Lead in Dynamic Sealing Systems · 2016. 2. 25. · AFM Confocal, WLI,...
Transcript of Inspection for Texture and Lead in Dynamic Sealing Systems · 2016. 2. 25. · AFM Confocal, WLI,...
Inspection for Texture and Lead in Dynamic Sealing Systems
Agenda
• Introduction• Bruker, BNANO Group
• 3D Metrology, Engineered Surfaces• Overview, Intro to 3D WLI• Application to sealing surface metrology
• Summary/Questions
Introduction - BNANO GroupServing a Wide Range of Analytical Instrument Needs
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refractories
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BNANO is a part of Bruker
Bruker headquarters in Billerica, Massachusetts, USA
~$1.7B Revenues, 80% outside US
IntroductionSpeaker
Matt Novak, Ph.D.Director, ApplicationsTribology, Stylus and Optical Metrology, [email protected]
Agenda
• Introduction• Bruker, BNANO Group
• 3D Metrology, Engineered Surfaces• Overview, Intro to 3D WLI• Application to sealing surface metrology
• Summary/Questions
Overview, Various InspectionsEngineered surfaces - wide range of requirementsWide range of measurement technologies
nano-meter micro-meter milli-meter centi-meter meter
Surface Finish Waviness Shape and Form
AFM Confocal, WLI, etc. CMMStylus Fringe Projection,Photogrammetry,
Lidar, Laser Scanning, etc.
Very fine scale Mid-range scale Large scale“2.5 D” True 3D
SEM, Spectroscopy, other methods as well
• Microscope with special objectives used to create images + height map
Interference-Based Optical ProfilerAccurate Local (X,Y) + Z Images Texture (including Lead) Well Resolved
Coherence Scanning/Vertical Scanning Interferometry
Interference signal functions as a focus sensorResolution of height is independent of magnification/FOV
VSI
3D Optical Profiler – Image + HeightImaging Example
Stepped Surface
~ 40 µm
~ -110 µm
~ 150 µm range
Images traditionally displayed as a color look up table (e.g., red high, blue low)
…or displayed in grayscale to look like SEM as well
3D Optical Profiler Surface ImagingVarious Display Options
Can provide enhanced images showing varioussurface texture differences or defects
3D Optical Profiler Surface ImagingVarious Display Options
Agenda
• Introduction• Bruker, BNANO Group
• 3D Metrology, Engineered Surfaces• Overview, Intro to 3D WLI• Application to sealing surface metrology
• Summary/Questions
Functional Sealing SystemsMany Inputs, Complex Interactions
Seal, Shaft Materials
Dynamic Sealing System
Operating Conditions
Assembly, Alignment
Manufacturing Process, Surface Finish
Additives, Lubricants
Manufacturing Process, Surface Finish
Machining Influence on TextureExamples of 3D Areal Images – NB Directionality
• Flat lapping/Reaming • Grinding
• Horizontal Milling
• Vertical Milling
• Turning
3D Image of Journal Sealing SurfaceShows micro-structural nature of surface
Cylinder stitch showing sealgroove ~ 4 µm depth and microstructures on the overall surface
Wide area, high resolution images are obtained with 3D optical profiling - enable detailed study of surfaces
Industry Case StudyWhat Differentiates Sealing System Function, Accounts for Performance Change?
• Six shafts (sealing journal surfaces), used in dynamic application
• Bruker approached (independently) by system end-user and shaft manufacturer/supplier – (initially regarding shaft lead)
• Two of six systems fail initial functional test (fixed temperature, pressure, sealed fluid test)
Grinding Process A
Grinding Process B
Controls Made for All InputsWhat About Shaft Surfacing, Resulting Finish?
• Process control cannot always guarantee functional differences• What about resulting surface finish (given other controls)?
Shaft Texture PreparationImportant to Function of Sealing Systems
• Burr, pore, scratch/ defect free surfaces
• Ra, Rz, Rpm of surface play a part
• Good topography, non-oriented lead (zero lead)
• Good concentricity of shaft to seal housing
Detail: RSS Tech Manual – Freudenberg-NOK Sealing Technologies
• Standard 2D texture, 3D Areal Parameter Analyses• … per ISO (4287/4288 or 25178-2) standards
• Variety of parameters (height, spatial, functional, hybrid)
• Micro lead analysis capability• Bruker-designed algorithm, non-contact lead
angle measurement of rotary shaft surfaces
• Macro twist analysis per MBN 37001-7• Licensed algorithm to compute macro lead per
MBN 31007-7 standard
Shaft Surface TextureComputations Made for Comparison using 3D WLI
Shaft Surface Texture: S Parameters2D and 3D Data Collection
• 2D Example: 20mm scan = 2.5 minutes = 500pts; 40um resolution
• 3D: 20mm scan = 2.5 minutes = 9,900,000pts; 7.92um resolution
Ra = 0.262 micron
Rz = 1.689 micron
Rp = 0.813 micron
Ra = 0.265 micron
Rz = 1.668 micron
Rp = 0.801 micron
Ra Rz Rp
Sample A – 2D Cross Section from 3D data
Sample A – Industrial Stylus
Shaft Surface TextureCorrelation Non-Contact/Contact MetrologyProper Sampling and Filtering are Key!
3Di view ofmicro lead angle
Shaft Surface Texture Surface Lead, Lead Angle, or Twist (Drall)
Bruker Nano Surfaces Division- Stylus and Optical Metrology
“Macro” vs. “Micro” Lead
Macro lead: Here this means periodic features imparted to sealing surface due to machining
preparation – if too deep or prevalent, seal mayleak right away
Micro lead: Aperiodic, main feature is a perpendicularity variation with respect to the shaft axis - seal will possibly leak in longer timeframe
What is Lead Angle?A word on Macro vs. Micro Lead…
Zero Lead AngleDid Not Explain System Functional Test Difference
Surface Texture, GeometryRoughness, Form Don’t Explain System Functional Test Difference
All shafts in spec for form and surface roughness per drawings
Rz 2.7 um Ra ~ 300 nm
Shaft- UnwornSa 368nm
Sds 1130 /mm2
Ssc 49 mm-1 (radii 20m)
Sa 769 nm
Sds 247 /mm2
Ssc 6 mm-1 (radii 166 m)
Shaft- worn600 m
Shaft Surface Texture: S ParametersSds, Ssc other indicators of function
S Parameter - Skewness
Skewness – Are peaks or valleys predominant?
Surface with positive Ssk – peaks predominant
Ssk Over Wide Area ImagesBrings Insight…
A1 A2 A3 A4 B1 B2
• B2 shaft micro lead higher than others..
• Possible benefit - reverse pumping, preventing leak
• If too powerful, debris/grit may be pulled into sealing region (problematic)
Agenda
• Introduction• Bruker, BNANO Group
• 3D Metrology, Engineered Surfaces• Overview, Intro to 3D WLI• Application to sealing surface metrology
• Summary/Questions
Summary
• Introduced Bruker, Bruker Nano Group, TSOM
• Introduced 3D white light interference based optical microscope (optical profiler)
• Showed utility of 3D WLI system for lead and texture metrology – problem resolution• Industry case study - dynamic functional sealing system
• Macro / Micro lead angle alone cannot explain performance • Interaction between measured parameters – insight to
performance • 3D data are very useful for gaining broad insights to surface
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