ROUGHNESS METER: WHAT IT IS FOR, HOW IT WORKS, TYPES - TECHNOLOGY - 2025

The roughness meter is a device used to calculate the roughness of some materials on the outside. By making these measurements it is possible to know the deterioration that this surface may suffer, the hardness and also the level of friction that it allows. This information is relevant especially when manufacturing certain objects or parts at an industrial level.

There are different types of roughness meters that depend on the site and the function that you want to give them. Currently it is even possible to find them portable for measurements in smaller productions or at the workshop level. There are also others that can be used in laboratories to measure a larger amount of data.

Example of a roughness meter. Source: Francesc.bach, via Wikimedia Commons.

The use of the roughness tester is usually common to establish the characteristics of parts such as shafts, bearings, rollers and even screws. It is undoubtedly a fundamental tool in the automotive sector, for example.

The measurements that are made with the roughness meter allow to detect the roughness that surfaces that normally cannot be detailed by the human eye.

What is the roughness meter for?

Its name allows you to quickly know what its function is. Measure the roughness of certain parts. The objective is to speed up the processes but without losing quality in the finishes.

It is one of the instruments that metrology uses to perform optical analysis. Waves are used to collect the data.

Measurements can be performed in a matter of seconds, which is why it is such a device so widely used on an industrial level. It is in charge of the microgeometry part of the surfaces.

In simple words, the roughness tester is a measuring instrument that allows you to calculate the quality level of certain parts.

It is possible to use the roughness tester in different areas, specifically in those that have to do with industrial processes. It measures the depth of undulations that are not visible to the naked eye. It also establishes the quality of the surfaces.

They are tools widely used in the study of parts that have to do with mechanical processes because it measures the roughness of the parts and is also capable of establishing the amount of wear they have or the resistance they are capable of offering.

History

Measuring roughness was not considered relevant in the past. Even metrology as a science did not take this study into account. It was an area that took on importance in more recent times.

Manufacturers

There are several countries that produce roughness meters, although the best known are great powers such as Japan, the United States, China, Germany and even Switzerland.

Prices vary depending on the amount of data they can measure and the margin of error they are able to guarantee. They can cost hundreds, thousands or millions of dollars.

How does it work?

It is a very simple device to use. It should only be put in contact with the surface to be analyzed. It is important to clean the object to be studied and that the operator of the roughness meter wears gloves so that no type of alteration occurs during the reading.

The person in charge of the roughness tester should pass it over the surface in a straight direction and continuously. The reading made by the device is then displayed on a screen where it is capable of reflecting unevenness ranging from 0.08 millimeters to 25 millimeters.

It is important to note that it is not necessary to press the measuring instrument against the surface. Just zoom in on the tool to perform the corresponding analysis. It is a detail of great importance because the roughness meters are sensitive to sudden movements.

It presents three different types of parameters which are Ra, Ry and Rz. Ra refers to the average roughness; Rz reflects the value of the highest height of the surface; while Rz establishes the average between the steepest heights and the deepest sites.

Elements of the roughness meter

Although it all depends on the type of roughness meter used, these devices are made up of some parts that are usually common in all cases, such as the probe head, the transducer, filters (which can be mechanical or electrical), drag box and calculator.

What allows measurements to be made are sensors in some cases, there are models that use probes and in some models both elements are combined.

The head, for example, is one of the most important parts because it is the one that touches the surface and allows you to go over it to measure unevenness. These heads usually have diamond tips because they offer greater resistance than other materials may have.

The information is then captured by the transducer and sends the signals to the calculator that analyzes everything that has to do with heights, widths and depths.

Care

Handling the roughness tester is simple, but it should not be forgotten that it is a measuring device, so it must be used with care. It is important to clean the elements that make up the roughness tester between measurements, especially those parts that came into contact with other surfaces.

Types

There are several types of roughness meters that are available on the market. Choosing the correct one depends on the function that is going to be given to this tool and on the amount of data to be extracted from each study.

They are normally divided into roughness meters that can be in contact with surfaces and those that do not need to be in contact.

In the first case, the roughness meters only have probes. While the tools that do not need contact work with a laser, although they can also have a probe. In the case of having both elements, the roughness meter price is usually much higher.

Stylus roughness tester

The probe is the element that is in charge of recognizing all the imperfections during the journey of a surface. In this case, they can also be divided into different types that have to do with those that are characterized by being induction and others that have a mechanical device.

Stylus laser roughness tester

They are usually the most accurate roughness meters that exist today.

Laser probe roughness

It relies on the use of waves to capture information. The laser that is used can be of two different types: an electrical sensor or one that uses the piezoelectric effect.

References

1. Adval de Lira, F. (2015). Dimensional Metrology: Measurement Techniques and Instruments for Control. São Paulo: Eixos Series.
2. Millán Gómez, S. (2012). Metrology and tests. Madrid: Paraninfo.
3. Núñez López, P. (2001). Experimental analysis of surface quality in material removal processes. Cuenca: Editions of the University of Castilla-La Mancha.
4. Mexican magazine of engineering and architecture: organ of the Association of Engineers and Architects of Mexico. (1926). 4th ed. Engineering and architecture publishing company.
5. Vázquez Vaamonde, A. and Damborenea, J. (2000). Science and engineering of the surface of metallic materials. Madrid: Higher Council for Scientific Research.