Hello everyone,
I have a technical question that comes up repeatedly in my work with machine components: Why do Malm screws loosen over time, even though they were tightened correctly? I understand that screws can generally loosen due to vibrations or mechanical stresses, but with Malm screws, this issue seems to occur more frequently and sometimes even faster. Are there structural or engineering reasons that promote loosening? Is it a material issue, a design flaw, or do installation and environmental factors play a bigger role? I would like to understand if there are preventive measures to stop these screws from loosening and which physical or mechanical processes are involved. Thank you in advance for your insights and experience!
I have a technical question that comes up repeatedly in my work with machine components: Why do Malm screws loosen over time, even though they were tightened correctly? I understand that screws can generally loosen due to vibrations or mechanical stresses, but with Malm screws, this issue seems to occur more frequently and sometimes even faster. Are there structural or engineering reasons that promote loosening? Is it a material issue, a design flaw, or do installation and environmental factors play a bigger role? I would like to understand if there are preventive measures to stop these screws from loosening and which physical or mechanical processes are involved. Thank you in advance for your insights and experience!
The loosening of Malm screws is usually the result of several factors acting together on mechanical and physical levels. Primarily, vibrations, temperature changes, and dynamic loads lead to a gradual loosening. These varying forces cause small relative movements in the screws, which reduce the preload clamping force holding the threads together.
Additionally, material fatigue and microscopic surface roughness can cause the connection to loosen over time. If the installation was done without the correct torque or without appropriate locking devices, the issue worsens.
In conclusion: the main causes are typically vibrations combined with insufficient preload or missing locking mechanisms.
Additionally, material fatigue and microscopic surface roughness can cause the connection to loosen over time. If the installation was done without the correct torque or without appropriate locking devices, the issue worsens.
In conclusion: the main causes are typically vibrations combined with insufficient preload or missing locking mechanisms.
The term "Malm screw" is not clearly defined, but I assume you are referring to specific screw connections used in mechanical engineering or specifically in metal-to-metal joints. Essentially, the loosening of these connections mainly depends on the type of force transmission and the preload tension.
Under dynamic loads, such as those caused by vibrations or cyclic forces, small movements occur between the contact surfaces. These micro-movements can gradually cause the screw to loosen, as the screw head and the nut move against each other.
Another factor is the so-called "creep" in the material, especially at high temperatures or in components subjected to continuous loading. Here, the preload tension of the screw decreases over time, which in turn promotes loosening.
Additionally, the surface condition plays a role: if the friction between the thread and the contact surface is not sufficiently high, the screws can turn more easily. To counteract this, locking compounds, spring washers, or self-locking nuts are often used.
My question to you is: what sizes and loads are typical for your Malm screws? And in which application area do you use this type of connection? This information could help to investigate the causes more precisely.
Under dynamic loads, such as those caused by vibrations or cyclic forces, small movements occur between the contact surfaces. These micro-movements can gradually cause the screw to loosen, as the screw head and the nut move against each other.
Another factor is the so-called "creep" in the material, especially at high temperatures or in components subjected to continuous loading. Here, the preload tension of the screw decreases over time, which in turn promotes loosening.
Additionally, the surface condition plays a role: if the friction between the thread and the contact surface is not sufficiently high, the screws can turn more easily. To counteract this, locking compounds, spring washers, or self-locking nuts are often used.
My question to you is: what sizes and loads are typical for your Malm screws? And in which application area do you use this type of connection? This information could help to investigate the causes more precisely.
glamo schrieb:
My question to you: What size and load capacity are typical for your Malm screws? And in which application areas do you use this type of connection?Thank you for your detailed response! I mainly work with M12 Malm screws, which typically transmit forces of several kilonewtons, especially in mechanical drive components exposed to vibration (e.g., conveyor systems). The ambient temperature usually ranges between 10 and 40 degrees Celsius (50 and 104 degrees Fahrenheit), although humidity and dirt are sometimes present. Locking devices are often used, yet many colleagues report unexpected loosening after just a few weeks. Are there specific material combinations or coatings that you would recommend to minimize the risk of loosening?
Based on your description, the phenomenon of "screw loosening due to frequency overlap" fits well. This occurs when low-frequency vibrations act near the resonance frequency of the screw or adjacent components, leading to increased relative movement.
A proven method to prevent this is using elastic locking elements, such as spring washers or disc springs, which maintain a constant preload.
Additionally, screws with special surface coatings, such as phosphating or zinc flake coatings, can increase friction and thus make loosening more difficult.
A proven method to prevent this is using elastic locking elements, such as spring washers or disc springs, which maintain a constant preload.
Additionally, screws with special surface coatings, such as phosphating or zinc flake coatings, can increase friction and thus make loosening more difficult.
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