Stylus method - the basis of tactile roughness measurement

The stylus method is one of the most precise and most frequently used methods for measuring surface roughness. It belongs to the group of tactile roughness measurement methods and is primarily used in quality assurance and the manufacturing industry to check the surface quality of workpieces.

What is the stylus method?

In the stylus method, the roughness of a surface is measured using a so-called stylus instrument measured. A fine diamond stylus moves mechanically over the surface to be measured. During the process, the stylus records the unevenness of the surface by detecting differences in height and depth. These deviations are converted into electrical signals, digitized and then analyzed to determine roughness parameters such as Ra (arithmetic mean of roughness) or Rz (average roughness depth) to be calculated.

The method is based on the principle of direct contact and delivers extremely precise results - even with microscopic unevenness. This makes it an essential component of stylus methods.

How does the stylus method work?

1. Preparation of the measurement: Clean the surface of the workpiece thoroughly so that no impurities distort the measurement.
2. Probe movement: You move the stylus over the surface and determine a defined measuring distance, the so-called stylus section length. This procedure is typical for the stylus method.
3. Data acquisition: As the stylus moves, you record the profile curve of the surface. This curve provides detailed information about the roughness.
4. Evaluation: You then analyze the recorded data and convert it into standardized roughness parameters, which are often defined in manufacturing standards.

Advantages

• High precisionIt enables measurements with an accuracy in the micrometer range.
• Conformity to standardsThe process meets international standards such as ISO 4287, which makes it universally applicable and a key strength of the stylus method.
• versatility: It is applied to a wide range of materials including metals, plastics and glass.

It is also comparatively inexpensive, as the devices are robust and durable.

Limitations of the stylus method

Despite its precision, there are also some limitations:

• Sensitivity to soilingDust or oil on the surface can falsify the measurement results.
• contact-based methodSince the stylus moves directly over the surface, there is a risk of scratches on sensitive materials, which must be taken into account in the practice of the stylus cutting method.
• time expenditureCompared to non-contact measurement methods, it can take longer to carry out.

For particularly sensitive or complex surfaces, alternative methods such as optical roughness measurement may be more suitable.

Conclusion

The stylus method is the basis of tactile roughness measurement and impresses with its precision, reliability and conformity to standards. It is ideal for industrial quality control, but requires careful preparation and is not always the best choice for sensitive surfaces. Despite its limitations, it remains one of the most proven methods for determining surface roughness and a key component of the stylus method.