ISO vs. ASME: The Basics of Surface Profile Filtering

Presentation Overview A brief history of ISO and ASME ISO vs. ASME The basics of surface profiler filtering Roughness and waviness Improvements in software ease of use Practical applications of stylus profilers How stylus and noise can filter data References 2

ASME History ASME was founded in 1880 to provide a setting for engineers to discuss the concerns brought by the rise of industrialization and mechanization. ASME gained prominence after a boiler explosion caused the Grover Shoe Factory Disaster in Brockton, MA on March 10, 1905 (killing 58 people and injuring 150) Having established the Boiler Testing Code in 1884, ASME formed a Boiler Code Committee in 1911. The ASME code was later incorporated into laws in most US states and Canadian provinces. Grover Shoe Factory Disaster Brockton, MA 3

ISO History Began in 1926 in New York as the International Federation of the National Standardizing Associations (ISA). Focused heavily on mechanical engineering. It was disbanded in 1942 during the second World War. In 1946, delegates from 25 countries, met at the Institute of Civil Engineers in London, to form an international organization To facilitate the international coordination and unification of industrial standards". Even the name of the organization is standardized. The name, "ISO" is not an acronym but was derived from the Greek word "isos" meaning "equal". The relation to standards is that if two objects meet the same standard, they should be equal. 4

ISO vs. ASME European automakers typically apply ISO standards and US automakers apply ASME standards. ISO is predominate in western European countries like Germany, France, and Italy. But not necessarily in eastern European countries like Poland, Hungary, and Romania (These countries have adopted ASME, because it provides them access to the US market). 5

ISO and ASME and Stylus Profiler Filtering Stylus Profiler: Collects data from the sample surface Real Profile Total Profile: Unfiltered data produced by the stylus profiler Primary Profile: Data after the short cutoff filter is applied (cutoff spatial frequency of λs to remove noise). 6

The Long and Short of Filtering Primary Profile Example: Both high frequency roughness and low frequency waviness (as well as shape curvature) 7

The Long and Short of Filtering Primary Profile Example: Both high frequency roughness and low frequency waviness (as well as shape curvature) 8

The Long and Short of Filtering Roughness Profile Example: Sampling length is equal to the filter cutoff wavelength used to separate roughness from waviness (λc). Spatial frequency > cutoff wavelength = roughness profile 9

The Long and Short of Filtering Waviness Profile Example: Sampling length is equal to the filter cutoff wavelength used to separate roughness from waviness (λc). Spatial frequency < cutoff wavelength = waviness profile 10

The Long and Short of Filtering Shape Profile Example: The waviness profile can be filtered once more, at an even longer cutoff wavelength, in order to separate the waviness and form 11

The Long and Short of Filtering: Definitions Traversing Length: Distance of the scan (total profile) Evaluation Length: Selected portion of the scan for evaluation Total and primary profiles Sampling length = evaluation length Sampling Length: < evaluation length. Roughness and waviness profiles Sampling length = cutoff length (λc). 12

The Long and Short of Filtering Sampling Length: < evaluation length. Segments of a profile showing distance between peaks and adjacent valleys, as well as identification of additional peaks Based on ISO 4288 standards. 13

ISO vs. ASME Ra Example ISO 4287 & 4288 ASME B46.1 Ra = (Ra1 + Ra2 + + Ran)/n Where Ran calculated on a roughness profile over the sampling length n. n is a number of sampling lengths. Ra = ( Z1 + Z2 + + ZN )/N Where N is a number of data points of roughness profile over an evaluation length. Z is height value of roughness profile ISO 4287 computes the values over the entire evaluation length (and sometimes computes the values within a sampling length) ISO 4288 and ASME B46.1, modifies this computation methodology to include estimates of parameters (computed over one sampling length) versus average value of parameters (computed over all available sampling lengths within the evaluation length) 14

Filtering Example Stylus Profiler Total Profile (Raw unleveled data) DektakXT Quick-Analyzer Software (Select Data Leveling) 15

Filtering Example Stylus Profiler Select Leveling Type (2-point or linear fit) Select Roughness button to display filtering options 16

Filtering Example Stylus Profiler Filter Analysis Settings displayed Select ISO 4287 or ASME B46.1 17

Filtering Example Stylus Profiler Filter Analysis Settings displayed Select ISO 4287 or ASME B46.1 Select Filter Type 18

Filtering Example Stylus Profiler Filter Analysis Settings displayed Select ISO 4287 or ASME B46.1 Select Filter Type Select Bandpass Filter 19

Filtering Example Stylus Profiler Filter Analysis Settings displayed Select ISO 4287 or ASME B46.1 Select Filter Type Select Bandpass Filter Or Select Short & Long Cutoff 20

Filtering Example Stylus Profiler Filter Analysis Settings displayed Select ISO 4287 or ASME B46.1 Select Filter Type Select Bandpass Filter Or Select Short & Long Cutoff Select Pa: Total or Primary Profile 21

Filtering Example Stylus Profiler Filter Analysis Settings displayed Select ISO 4287 or ASME B46.1 Select Filter Type Select Bandpass Filter Or Select Short & Long Cutoff Select Ra: Roughness Profile 22

Filtering Example Stylus Profiler Filter Analysis Settings displayed Select ISO 4287 or ASME B46.1 Select Filter Type Select Bandpass Filter Or Select Short & Long Cutoff Select Wa: Waviness Profile 23

Filtering Example Stylus Profiler Filtered Analytical Results for Ra, Wa & Pa 24

Filtering Example Stylus Profiler Database results comparing multiple measurements 25

Filtering Example Stylus Profiler 3D Measurement (DektakXT Stylus Profiler) 26

Filtering Example Stylus Profiler 3D Cross-section Roughness and Area Roughness 27

3D Resolution and Filtering How Profile Density Filters Data Depends on the spacing between each individual profile (1um min.) 3D maps can be generated from 10 or 10,000 profiles High resolution 3D maps can take hours to complete 3D Area Surface Texture 10mm x 10mm MEMS Micro Fluidic Channels 3D images created from multiple individual profiles Large Map Areas 28

How Stylus Size and Shape Filters Data 60 2 um Radius 12.5um Radius 45 2um radius stylus is specified for surface texture measurements 60º cone angle tip (ASME compliance) 45º cone angle tip (ISO compliance) Larger tips (such as 12.5um radius) act as a filter to smooth data 4/26/2012 29

How Data Point Density Filters Data Lateral Resolution: Data Point Density: Too few data points can act to smooth surface profile DektakXT offers up to 120,000 data points per scan DektakXT maximum data point density = 0.003um/data point 4/26/2012 30

How Noise Can Filter Data Ways to Reduce Noise: Stable Platform: Lower noise floor achieved with stable sensor support Vibration Isolation: Filter out external noise & vibration Electronics: Low-noise electronics and shielded cables Environmental Enclosure: Reduces affects of acoustic noise and air currents Measurement repeatability of better than 5 Angstroms achieved with DektakXT Built-In Vibration Isolators Environmental Enclosure Low Noise Single-Arch Support 31

Selecting the Right Tool for the Job AFM: Highest resolution with multiple modes and applications Optical Profiler: High Z resolution, non-contact high-speed 3D scans Stylus Profiler: High measurement repeatability of 2D profiles Atomic Force Microscopy Nanoscale characterization of electrical, magnetic, compositional and material properties Optical Profiling Non-contact 3D measurement of surface texture and roughness Stylus Profiling Measure thin film step heights, stress and surface texture 4/26/2012 32

Application Paper & References ISO Standardized Filtering for DektakXT Stylus Profiler Provides more detailed information on the various ISO and ASME parameters for measuring roughness and waviness Available on the Bruker website: www.bruker.com ISO Geometrical Tolerancing Reference Guide by Alex Krulikowski (Compares and contrasts ISO and ASME standards) ISO 4287, Geometrical Product Specifications (GPS) ISO 4288, Geometrical Product Specifications (GPS) ASME B46.1-2002 (Surface Roughness, Waviness, and Lay) 33