{"id":1746,"date":"2024-10-11T07:07:46","date_gmt":"2024-10-11T06:07:46","guid":{"rendered":"http:\/\/guemisa.es\/?post_type=documentos-pdf&p=1746"},"modified":"2026-11-03T13:41:16","modified_gmt":"2026-11-03T12:41:16","slug":"some-types-of-vibration","status":"publish","type":"documentos-pdf","link":"https:\/\/guemisa.es\/en\/documentos-pdf\/algunos-tipos-de-vibracion\/","title":{"rendered":"Types of vibration in machines: causes, frequencies and correction"},"content":{"rendered":"
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Technical guide \u00b7 GUEMISA<\/p>\n

Imbalance<\/span>Lack of alignment<\/span>Bearings and bushings<\/span>Gears and belts<\/span>Electrical failures<\/span><\/div>\n
Quick response<\/b>Each cause of vibration leaves a characteristic frequency: imbalance 1x rpm<\/b>, misalignment 1x, 2x and 3x rpm<\/b>, mechanical loosening 2x rpm and multiples<\/b> and oil whirlwind 46 to 48% of the shaft rpm<\/b>. Identifying the predominant amplitude allows you to determine the cause and correct it.<\/div>\n

Characteristic frequency by cause<\/h2>\n
Cause<\/th>Vibration frequency<\/th>Indicated features<\/th><\/tr><\/thead>
Imbalance<\/td>1x rpm of the rotor shaft<\/td>Amplitude proportional to the imbalance; greater in the radial direction; stable phase<\/td><\/tr>
Lack of alignment<\/td>1x rpm; also 2x and 3x in severe cases<\/td>Amplitude proportional to misalignment; high also in the axial direction; unstable phase<\/td><\/tr>
Defective rolling elements<\/td>High frequency, not necessarily an integer multiple of the rpm<\/td>The amplitude depends on the severity and type of fault<\/td><\/tr>
Oil whirlwind<\/td>From 46 to 48% of the shaft rpm<\/td>Only in machines with pressure-lubricated bearings, at high speeds<\/td><\/tr>
Whirlwind of hysteresis<\/td>Equal to the first critical speed of the rotor<\/td>Rotor between the first and second critical speed<\/td><\/tr>
Dry whip (inadequate lubrication)<\/td>Very high, not an integer multiple of the rpm<\/td>Squeaking sound of a bearing running dry<\/td><\/tr>
Mechanical loosening<\/td>2x rpm and higher multiples<\/td>Probable primary cause if the amplitude at 2x exceeds half that of 1x<\/td><\/tr>
Control straps<\/td>Integer multiple (1, 2, 3 or 4) of the belt rpm if the defect is in the belt<\/td>If it reacts to other forces, it vibrates at the altering frequency<\/td><\/tr>
Gears<\/td>Gear frequency: number of teeth per rpm of the gear<\/td>A single broken tooth can produce 1x rpm, with pulse signals<\/td><\/tr>
Electrical failures<\/td>1x rpm<\/td>It disappears when the power is disconnected; it varies with the motor load.<\/td><\/tr><\/tbody><\/table><\/div>\n

Imbalance, misalignment, and eccentricity<\/h2>\n

Imbalance is one of the most common causes of vibration. The phase shifts 90\u00b0 if the sensor shifts 90\u00b0. In a cantilevered rotor, imbalance typically produces a large axial amplitude in addition to the radial amplitude.<\/p>\n

Even with flexible couplings, misalignment results in radial and axial forces. If the axial amplitude exceeds half the highest radial reading, there is reason to suspect an alignment problem or a bent shaft.<\/p>\n

Type of misalignment<\/th>Main vibration<\/th><\/tr><\/thead>
Angular<\/td>Axial, at the rotational speed of the shaft<\/td><\/tr>
In parallel<\/td>Radial, at twice the rotational speed of the shaft<\/td><\/tr>
Combination of both<\/td>Radial and axial<\/td><\/tr><\/tbody><\/table><\/div>\n

Eccentricity means that the centerline of the shaft does not coincide with that of the rotor. To differentiate it from imbalance in a motor, the vibration is measured with the filter removed and the motor disconnected: if the amplitude gradually decreases as it rotates due to inertia, imbalance is likely; if it disappears upon disconnection, the cause is electrical.<\/p>\n

Bearings and bushings<\/h2>\n

Defects in the raceways, balls, or rollers of rolling element bearings cause high-frequency vibrations. The defective bearing is usually the one closest to the point of highest vibration of this type.<\/p>\n

Common causes of rolling element bearing failures:<\/p>\n