A common occurrence of rotational vibration is an extreme vibration along the crankshaft whose frequency is the same as shaft speed. When the vibration of external piping becomes excessive, it is almost certainly because some vibration within the system is occurring at a frequency near the natural frequency of the piping structure. An example of translational vibration is the motion of external piping due to resonance. Types of Vibration in Compressor Systems The two predominant vibration types in compressors are translational (lateral) and rotational (twisting) vibration. ![]() ![]() Ariel compressors are designed so that the system's natural frequencies are far away from normally occurring vibration frequencies. Breakdowns will result at an accelerated rate. In real machinery when a structure enters resonance (vibrates at its natural frequency), vibration amplitudes are magnified. Mechanical structures, which should be designed not to ring easily, won't ring for long - unless the exciting force is continuous. Tuning forks will ring for a long time but not forever. When an external force (e.g., a hammer blow) excites a structure, it will "ring" at its natural frequency until damping forces within the structure stop the vibration. The tuning fork will emit a sound at its natural frequency. The best example of a natural frequency is striking a tuning fork. Natural Frequency - Ringing the Tuning Fork This mechanical system forms a structure that has one or more natural frequencies. The compressor unit(s), dryers, intercoolers, piping, etc., all combine to form a complex mechanical system that transmits vibration energy. How Vibration Affects Compressors When you consider how vibration happens in a compressor, you have to consider the compressor unit and all peripheral equipment attached to it. Ariel takes special care in the design and manufacturing processes to prevent these conditions from occurring. In compressors, however, the most common causes are unbalance in rotating parts and abnormal aerodynamic forces. What Causes Vibration? Vibration can be caused by a variety of conditions including bent shafts, unbalance in rotating parts, worn or bent gears, damaged bearings, misaligned couplings or bearings, electromagnetic forces, etc. If this vibration-related movement becomes too great, damage to the machine will result. These forces are usually related to the movement of various parts within the machine. No matter how rigidly a machine is mounted, the machine and all attached structures will experience some undesirable motion caused by various forces. Why Worry about Vibration? Every machine vibrates as it operates. ![]() Unbalance - The Primary Vibration Concern in Compressors Why Worry about Vibration? What Causes Vibration?
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