A linear motion system must move accurately and in a controlled manner. However, unwanted vibrations can occur during acceleration, deceleration or positioning. This affects the accuracy, wear and service life of components. Vibrations in linear motion systems have various causes, ranging from mechanical play to incorrect software settings. By carefully investigating the cause, it becomes clear which adjustments are needed to make the movement more stable. But here too, prevention is better than cure.
What causes vibrations in linear motion systems?
A vibrating linear axis does not automatically mean there is something wrong with the guide itself. In practice, we often see that the cause lies elsewhere in the system. Mechanical play, insufficient stiffness, misalignment, resonance and incorrect software settings are common causes. Sometimes there is one clear problem. In other cases, several factors reinforce each other.
Mechanical play is a good example. When components are not securely connected or there is too much clearance in the drive system, unwanted movement occurs. This can cause the axis to vibrate, particularly during acceleration and deceleration. The stiffness of the structure also has an influence. A thin mounting plate or a machine frame that is not sufficiently rigid can deform under load. This deformation affects the movement of the axis.
Misalignment and resonance
Misalignment can also cause problems and vibrations. If guide rails or drive components are not correctly aligned with each other, additional forces and uneven resistance occur. As a result, movement is less smooth than intended. This may become noticeable through vibrations or jerky motion.
Another cause is resonance. Every machine structure has natural frequencies at which it is particularly susceptible to vibration. When the movement of the machine excites one of these frequencies, vibrations can become stronger. For example, a linear axis may move smoothly at low speeds but suddenly start vibrating at a particular motor speed.
The effects of vibrations on accuracy and service life
A vibrating linear axis can make positioning less accurate. The carriage may continue moving briefly after stopping, meaning the desired position is not immediately stable. This can cause problems during precision machining or repeated picking and placing of products.
Vibrations also cause fluctuating loads on carriages, rails and the drive system. This can accelerate wear and shorten service life. The extent of the impact depends on the vibration intensity, load and operating duration.
Assessing vibration sensitivity during machine design
A rigid linear guide alone is not sufficient if the structure it is mounted on also flexes. That is why reducing vibrations starts with the overall design, during the engineering phase.
With FEM analysis, a calculation method in which the design is digitally divided into small elements, engineers can investigate stiffness and natural frequencies. This reveals which parts are susceptible to resonance. The results can help determine whether, for example, a mounting plate needs reinforcement or the support structure needs to be modified before the machine is built.
The software being used should also be checked. An overly responsive motor control system or a motion profile with abrupt accelerations can cause unwanted movements.
How do you identify the cause?
A good diagnosis starts by determining when the vibration occurs. The behaviour during acceleration, constant speed and standstill provides different clues.
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During acceleration or deceleration, the motion profile or motor control system may play a role.
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Within a specific speed range, resonance is a possible explanation.
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At a fixed position along the stroke, it is worth checking alignment, mounting and local resistance.
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After reaching the end position, residual vibrations in the structure and the control system can be investigated.
Measurements taken on the axis and frame can then help locate the source. The position deviation recorded by the control system also provides useful information. In the case of jerky motion, it is also advisable to check lubrication and possible contamination.
Keep in mind that simply reducing the motor speed may suppress the symptoms without eliminating the underlying cause.
Which adjustments reduce vibrations in linear motion systems?
Vibrations in linear motion systems can be reduced in several ways. A rigid structure, sufficient support and correct alignment of the guide and drive system contribute to more stable movement. Mounting also plays an important role. By ensuring that components are properly matched, unwanted forces and movements can be minimised as much as possible.
Adjustments to the drive system and motor control can also help. By allowing the axis to accelerate and decelerate more smoothly, vibrations and residual movements can be reduced. Which adjustment has the greatest effect depends on the complete motion system. Are you unable to identify the cause or find the right solution? At LM Systems, we are happy to help you find a suitable approach.
Choose the right linear components
Not every linear guide responds in the same way to varying loads and vibrations. The right choice depends on factors such as the required accuracy, moving mass and stiffness of the overall structure. A thorough assessment of these properties, for example in collaboration with an expert at LM Systems, helps minimise problems during operation. We offer various types of linear guides for a wide range of machine building applications. Within our product range, the different designs and technical properties can easily be compared, and the preload is set in advance to achieve the correct stiffness.
Want to know more about the possibilities? Through our engineering support, we are happy to help you with your design and the required specifications.