roughness and particle diameter of sandpaper · 320 67.18 ± 22.62 800 28.16 ± 8.58 2000 21.27 ±...
TRANSCRIPT
6 Morgan, Ste156, Irvine CA 92618 · P: 949.461.9292 · F: 949.461.9232 · nanovea.com Today's standard for tomorrow's materials. © 2018 NANOVEA
Roughness and Particle Diameter of Sandpaper
Prepared by Frank Liu
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INTRODUCTION: Sandpaper is a common commercially available product used as an abrasive. The most common use for sandpaper is to remove coatings or to polish a surface with its abrasive properties. These abrasive properties are classified into grits, each related to how smooth or rough of a surface finish it will give. To achieve desired abrasive properties, manufactures of sandpaper must ensure that the abrasive particles are of a specific size and have little deviation. To quantify the quality of sandpaper, Nanovea’s 3D Non-Contact Profilometer can be used to obtain the Sa height parameter and average particle diameter of a sample area. IMPORTANCE OF 3D NON-CONTACT PROFILOMETER FOR SANDPAPER When using sandpaper, interaction between abrasive particles and the surface being sanded must be uniform to obtain consistent surface finishes. To observe this interaction, the surface of the sandpaper can be observed with Nanovea’s 3D Non-Contact Profilometer to see deviations in the particle sizes, heights, and spacing. Surface height parameters (such as roughness (Sa)) can be used to quantify and identify the shape of the sandpaper’s surface. MEASUREMENT OBJECTIVE In this study, five different sandpaper grits (120, 180, 320, 800, and 2000) are scanned with Nanovea’s 3D Non-Contact Profilometer. The Sa is extracted from the scan and the particle size is found by conducting a Motifs analysis to find their equivalent diameter.
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RESULTS: The sandpaper decreases in surface roughness (Sa) and particle size as the grit increases as expected. The Sa ranged from 42.37um to 3.639um. The particle size ranged from 127 ± 48.7 to 21.27 ± 8.35. Larger particles and high height variations create stronger abrasive action than smaller particles and a smooth surface.
Please note all definitions of the given height parameters are listed on page.A.1.
Grit Sa Sz Sv Sp Sq Ssk Sku
120 42.37 527.2 235.7 291.5 59.45 0.314 4.397
180 27.28 350.4 174.7 175.8 37.83 0.2653 4.734
320 17.92 325.5 138.1 187.3 24.6 0.2388 5.008
800 6.273 119.4 45.35 74.05 8.492 0.6921 5.516
2000 3.639 62.04 17.89 44.15 4.659 0.5882 4.454
Table 1: Comparison between sandpaper grits and height parameters
Grit Equivalent Particle Diameter
120 127.0 ± 48.7
180 105.6 ± 35.43
320 67.18 ± 22.62
800 28.16 ± 8.58
2000 21.27 ± 8.35
Table 2: Comparison between sandpaper grits and particle diameter
2D/3D view of Sandpaper: Below are the false-color and 3D view for the sandpaper samples. A gaussian filter of 0.8mm was used to remove the form or waviness.
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180GRIT
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Motif Analysis: To accurately find the particles at the surface, the scanned surface was thresholded to only show the upper layer of the sandpaper. A motif analysis was conducted afterwards to detect peaks from the thresholded surface.
120 Grit 180 Grit
320 Grit 800 Grit
2000 Grit
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Number of motifs 35
Parameters Stat. Value Unit
Height Mean 98.75 µm
Std dev 36.02 µm
Equivalent diameter Mean 0.1270 mm
Std dev 0.04867 mm
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Number of motifs 47
Parameters Stat. Value Unit
Height Mean 61.68 µm
Std dev 24.51 µm
Equivalent diameter Mean 0.1056 mm
Std dev 0.03543 mm
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Number of motifs 67
Parameters Stat. Value Unit
Height Mean 47.12 µm
Std dev 18.82 µm
Equivalent diameter Mean 0.06718 mm
Std dev 0.02262 mm
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Number of motifs 199
Parameters Stat. Value Unit
Height Mean 12.77 µm
Std dev 5.859 µm
Equivalent diameter Mean 0.02816 mm
Std dev 0.008583 mm
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Number of motifs 384
Parameters Stat. Value Unit
Height Mean 4.020 µm
Std dev 3.136 µm
Equivalent diameter Mean 0.02127 mm
Std dev 0.008345 mm
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CONCLUSION: Nanovea’s 3D Non-Contact Profilometer was used to inspect the surface properties of various sandpaper grits due to its ability to scan surfaces with micro and nano features with precision. Surface height parameters and the equivalent particle diameters were obtained from each of the sandpaper samples using advanced software to analyze the 3D scans. It was observed that as the grit size increased, the surface roughness (Sa) and particle size decreased as expected. Learn more about the Nanovea Profilometer or Lab Services
6 Morgan, Ste156, Irvine CA 92618 · P: 949.461.9292 · F: 949.461.9232 · nanovea.com Today's standard for tomorrow's materials. © 2018 NANOVEA
Definitions of Height Parameters
Height Parameter Definition
Sa Arithmetical Mean Height
Mean surface roughness.
Sa = 1
A∬ |z(x, y)|dxdyA
Sq Root Mean
Square Height
Standard deviation of the height distribution, or RMS surface roughness.
Sq = √1
A∬ z2(x, y)dxdyA
Computes the standard deviation for the amplitudes of the
surface (RMS).
Sp Maximum Peak
Height Height between the highest peak and the mean plane.
Sv Maximum Pit
Height Depth between the mean plane and the deepest valley.
Sz Maximum
Height Height between the highest peak and the deepest valley.
Ssk Skewness
Skewness of the height distribution.
Ssk = 1
𝑆𝑞3[1
𝐴∬ 𝑧3(𝑥, 𝑦)𝑑𝑥𝑑𝑦𝐴
]
Skewness qualifies the symmetry of the height distribution. A negative Ssk indicates that the surface is composed of mainly
one plateau and deep and fine valleys. In this case, the distribution is sloping to the top. A positive Ssk indicates a
surface with a lot of peaks on a plane. Therefore, the distribution is sloping to the bottom.
Due to the large exponent used, this parameter is very
sensitive to the sampling and noise of the measurement.
Sku Kurtosis
Kurtosis of the height distribution.
Sku = 1
𝑆𝑞4[1
𝐴∬ 𝑧4(𝑥, 𝑦)𝑑𝑥𝑑𝑦𝐴
]
Kurtosis qualifies the flatness of the height distribution. Due to the large exponent used, this parameter is very
sensitive to the sampling and noise of the measurement.