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  • Surface Roughness Test

    The surfaces of materials or objects are extremely diverse, ranging from smooth and shiny to rough and matte. These differences are due to the varying surface roughness of a component and can affect its performance, functionality and aesthetics. Surface roughness testing is a common procedure used to measure and quantify surface texture and irregularities.

    Surface roughness is typically characterized by small variations in the height of a surface relative to a reference plane. These variations may be caused by factors such as machining processes, material properties, wear or corrosion. The purpose of surface roughness testing is to obtain numerical values that describe the nature and extent of these irregularities. It is an important quality control method in various industries such as manufacturing, engineering and materials science.

    Surface roughness testing machine.Fig 1. Surface roughness testing machine.

    T, C&A Lab can test the following roughness parameters

    T, C&A Lab determines the most important roughness parameters of a surface by measuring the 2D or 3D profile of the surface in question using a roughness measuring device. From this, the different roughness parameters characterizing the surface are calculated:

    • Arithmetic mean roughness (Ra)

    Ra is an internationally recognized roughness parameter. It is the arithmetic mean of the absolute values of the contour deviations within the reference distance.

    • Average roughness (Rz)

    The average roughness depth Rz is the arithmetic mean of the maximum individual roughness depths of several adjacent individually measured sections.

    • Maximum roughness (Rt)

    Rt represents the vertical difference between the deepest notch and the highest peak of the total measured section.

    T, C&A Lab checks surface height by Rz measurements and smoothness of sliding surfaces by Ra measurements. We usually use a combination of Ra and Rz analysis.

    Setup for surface roughness measurement.Fig 2. Setup for surface roughness measurement (Ra). (Samsudeensadham S, et al. 2015)

    T, C&A Lab offers a variety of surface roughness testing methods, including:

    • Contact Profilometry: In this method, a diamond-tipped stylus is traced across the surface using a profilometer or stylus instrument. The instrument measures the vertical movement of the stylus and generates a surface profile. From this profile, roughness parameters such as Ra can be calculated.
    • Optical Profilometry: Optical profilers use optical interferometry to measure surface topography. They project structured light onto the surface and use a camera to capture the reflected light. By analyzing the interference pattern, the instrument can determine surface roughness parameters.
    • Laser Scanning: Laser scanning systems use a laser beam to scan a surface and measure its topography. The laser beam is reflected from the surface and the resulting reflections are detected and analyzed to determine surface roughness characteristics.
    • Atomic Force Microscopy (AFM): AFM is a high-resolution technique that uses a sharp probe to scan a surface at the nanometer level. The probe interacts with the surface and the resulting force is measured.AFM provides detailed information about the surface roughness, including 3D morphology data.

    To find out more about our surface roughness testing services or to discuss your specific requirements, please contact us. Our experts will be happy to help you and provide you with the information you need.


    1. Samsudeensadham S, et al. "Study On Cutting Forces And Tool Wear During End Milling Of Ti-6al-4v Alloy." International Journal of Mechanical And Production Engineering. ISSN: 2320-2092.

    Note: this service is for Research Use Only and Not intended for clinical use.


    T,C & A LAB is an independent lab providing quality or custom testing, characterization and analysis of a variety of materials. Our engaged experts are ready to help you.

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