Pneumatically Controlled Loading System vs. Mechanical Servo Motor Tribometer: Comparative Analysis

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Tribology is an essential facet of various industries, ranging from automobiles to biomedical research. At its core lies the study of friction, wear, and lubrication. Tribometers are crucial in studying these characteristics, and there are various types available, including the pneumatically controlled loading system tribometer and the mechanical servo motor tribometer. In this article, we will delve into the comparison of the pneumatic tribometer to the mechanical servo motor tribometer, specifically focusing on each system’s stability, accuracy, and operational aspects.

Pneumatically Controlled Loading System Tribometer

The realm of tribology has seen many advancements in material testing. Leading this innovation is the use of pneumatic technology instead of traditional mechanical servo motors. Advanced pneumatic tribometers, such as the NANOVEA T100 and NANOVEA T2000, utilize an air medium for noise dampening and superior stability during testing.

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NANOVEA T100 Compact Pneumatic Tribometer

Stability and Accuracy

The use of an air medium in tribology for force application became possible because of advancements in pneumatic actuators that now offer high control of air pressure. The system relies on the natural property of air to control the force pressure exerted without having to use any aggressive PIDs that will not work on all materials and test conditions. Thus, the air medium offers exceptional stability even during high-speed evaluations over 5000 rpm.


Load Measurement

A pneumatic tribometer has a direct stiff connection between the surface of the samples under test and the load cell sensor used to precisely measure the load exerted on the sample surface. The load cell sensor maintains accurate load recording even at high speeds, allowing for detailed analysis of friction and wear properties. Obtaining such measurement accuracy is essential for achieving consistent and dependable results.

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Mechanical Servo Motor Tribometer

Unlike the pneumatic tribometer, mechanical servo motor tribometers require aggressive PID settings to constantly adjust the load. These PIDs need to be changed according to the nature of the sample under test in addition to the test parameters. Since this is impossible, especially at high speed, mechanical servo motor tribometers use a spring in between the load cell and the surface of the sample to absorb the vibration caused by the movement up and down of the sample under test. This allows the use of easier PIDs with less active control. Since the load cell is behind the spring, the data measured will look very smooth. It is, however, not the true force applied to the sample. The spring creates a natural averaging of that force. This spring will need to be changed if the sample is of a very different nature. Also, at a high speed, the difference between what the surface of the sample experiences and what is measured by the load cell increases drastically.

It is known that adding a vibration frequency in the Z direction creates faster wear than if this vibration is non-existent. Something similar to fretting vibration but in the loading direction. Since these tribometers don’t measure the exact load on the sample, this side effect can explain wear rate variation on samples that otherwise would not make much sense.

Spring Mechanism 

One of the main sources of error that affect the accuracy of results is the up and down movement during testing, a motion that can introduce vibrations and inconsistencies in the load applied to the sample surface. To counteract this, mechanical servo motor tribometers often rely on a spring mechanism between the load cell and the surface of the sample that helps reduce vibrations on the motor side. But, as useful as this feature can be, it can also contribute to discrepancies between the measured load and the actual load applied to the sample. Thus, researchers must account for these potential sources of error to ensure the accuracy and reproducibility of their test outcomes.

Advantages of The Pneumatic System 

The pneumatic loading system is an excellent choice for tribological studies and industrial applications due to its distinct advantages. It offers a much smoother motion than mechanical servo motor tribometers, which can introduce vibrations that affect the load applied to the sample surface.


Enhanced Stability

When it comes to measuring friction and wear characteristics, accuracy is key. That’s where the pneumatically controlled loading system comes in. Its inherent stability means that scientists and engineers can rely on consistent results on all materials.

Greater Accuracy 

The importance of accurate load measurement in analyzing tribological properties cannot be overstated. When working with a pneumatically controlled system, having a load cell sensor measuring the actual load on the surface of the sample is instrumental in ensuring that high-speed measurements correspond directly to the load being applied to the sample. This level of accuracy provides researchers with reliable data for comprehensive tribological investigations, which is crucial in advancing our knowledge of the field.

Operational Benefits 

Pneumatically controlled systems have revolutionized the way experiments are conducted and data is collected. The use of an air medium in such systems eliminates the need for complicated PID settings, therefore simplifying the entire testing process. This feature alone is a game-changer for scientists and researchers who often face immense pressure to produce accurate results within specific timelines. Another advantage of pneumatically controlled systems is the absence of a spring mechanism, which automatically often leads to discrepancies between measured and applied loads. This innovative system ensures enhanced reliability of test results, leaving no room for human error. These features make pneumatically controlled systems highly sought after in the scientific community due to the ease of use, reliability, and accuracy they provide.


Undoubtedly, pneumatically controlled loading system tribometers, like the ones developed by NANOVEA, present many advantages for tribological studies. Their stability and accuracy position pneumatic tribometers, employing an air medium and a load cell sensor, as the superior choice for precise measurements, even at high speeds.

Looking ahead, we anticipate further developments aimed at advancing state-of-the-art technologies in materials testing.

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1 Comment

  1. This seems like a neat solution. However, I am not quite sure if this is desirable, particularly when there is a large wear scar that could affect the measurements due to the rotation of normal and frictional forces. With the tribometer, we measure not the normal and frictional forces, but rather the contact force and tangential force, which are not the same. See the following references:

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