Application Note | Belt Surface Texture
Roughness & Texture of Polymer Belts Using 3D Profilometry
Textured vs Smooth Belts: Roughness, Texture Direction and Peak Uniformity
Research & Experimental Testing
Duanjie Li
Visual Design & Editorial
Andrew Shore
Introduction
A belt is a loop of flexible material that links rotating shafts for relative movement and power transmission. The combination of simplicity, low price and easy shaft alignment makes the belt drive an ideal option in farming, mining, and logging applications, such as bucksaws, sawmills, threshers, silo blowers and conveyors. There are several forms of belts, including flat belts, rope belts, round belts, V belts, multi-groove belts, etc. Depending on the specific requirements of the applications, the desired belt shape is selected.
Importance of Surface Texture for Belts
Surface finish of the belt is critical for its product quality and performance. The surface texture and uniformity play a critical role in the friction and service lifetime of the belt drive during operation. Sufficient friction ensures effective power transmission without slipping, but excessive friction may rapidly wear the belt. An accurate surface roughness and texture measurement of the belt is important for reliable product inspection and quality control.
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Measurement Objective
The roughness and texture of two belts were measured and compared using the NANOVEA ST400 optical profilometer to showcase the capability of the NANOVEA optical profilometer in providing comprehensive and user friendly surface analysis of belts with different textures.
NANOVEA ST400 Standard
Optical 3D Profilometer
Results and Discussion
The 3D view and false color view of the textured and smooth belts are compared in Fig. 2 and Fig. 3, respectively. The textured belt shows a repeated pattern, created by the extrusion process during production. In comparison, the smooth belt does not have any texture on the surface. As a result, the textured belt possesses a much higher roughness Sa of 33.53 µm, compared to 8.70 µm for the smooth belt, as summarized in Table 1.
| ISO 25178 parameter | Textured surface | Smooth surface | Note |
|---|---|---|---|
| Sa (µm) | 33.53 | 8.70 | Arithmetic mean height |
| Sq (µm) | 42.24 | 11.87 | Root-mean-square height |
| Sp (µm) | 337.26 | 204.10 | Maximum peak height |
| Sv (µm) | 139.84 | 100.94 | Maximum pit height |
| Sz (µm) | 477.10 | 305.04 | Maximum height |
| Ssk | 1.01 | −0.02 | Skewness |
| Sku | 3.71 | 6.90 | Kurtosis |
Table 1: Comparison of roughness of the textured and smooth belts.
Fig. 4 analyzes the surface texture isotropy of the textured belt. It can be observed that the belt texture has a preferential direction in the angle ranging from 100 to 150°, leading to a texture isotropy of 43%.
The 2D profiles along the axial direction of the textured belt are shown in Fig. 5. The height and distance of the peaks of the surface texture are fairly uniform. The peaks have an average height of ~130 µm.
Fig. 6 displays the two belts after wear tests. The textured belt exhibits a smaller wear track compared to the smooth belt. For the detailed analysis, refer to the application note Polymer Belt Wear and Friction Testing Using a Tribometer.
Conclusion
The roughness and texture of two different belts are measured using the NANOVEA ST400 non-contact profilometer. Such a measurement provides a useful tool in both development phases and quality control of the belts used in a variety of industries, including farming, mining, logging and many others. The analysis software provides measurements such as uniformity and roughness, texture isotropy and peak and valley profile, enabling users to have a comprehensive understanding of the belt surface texture.
The data shown here represents only a portion of the calculations available in the analysis software. NANOVEA Profilometers measure virtually any surface in fields including Semiconductor, Microelectronics, Solar, Fiber Optics, Automotive, Aerospace, Metallurgy, Machining, Coatings, Pharmaceutical, Biomedical, Environmental and many others.
Frequently Asked Questions About Belt Surface Texture
Why does belt surface texture matter?
Surface texture and uniformity control the friction and service life of a belt drive: enough friction transmits power without slipping, but too much wears the belt quickly, so roughness and texture are key to quality control.
How rough were the two belts?
The textured belt had Sa 33.53 µm and Sq 42.24 µm; the smooth belt had Sa 8.70 µm and Sq 11.87 µm (ISO 25178).
Where does the belt texture come from?
The repeated pattern on the textured belt is created by the extrusion process during production; the smooth belt has no surface texture.
Does the texture have a direction?
Yes. Texture isotropy analysis gave 43%, with a preferential direction between 100 and 150°.
How uniform are the texture peaks?
Along the axial direction the height and spacing of the peaks are fairly uniform, with an average peak height of about 130 µm.
Which belt wore less?
After wear testing the textured belt showed a smaller wear track than the smooth belt; the full analysis is in the companion belt wear and friction note.
