Motor Analytics

The following table contains the first principle failure modes embedded within FactoryTalk Analytics GuardianAI for motors. These may be provided as recommendations during deviation detection based on the matching frequency analysis of the deviation.

Failure Mode Label	Description
Unbalance	Unbalance may present in two ways, overhung or coupled. Consider two scenarios: A shaft supported by bearings on either end and fitted with bladed wheels or other masses, has an imbalance at some location other than dead-center. In this case, called ‘coupled’ unbalance, an imbalance nearer to one bearing than the other would cause the shaft to wobble. An overhung shaft, supported only on one end, and that has an imbalance some distance from the supporting bearing: Since the mass relative to the bearing is consistent, shaft motion is likely to be consistent. While it would move more at further distances from the bearing, it would always move in the same direction.
Shaft Misalignment	Misalignment refers to a condition where the components of a motor system, such as the motor shaft and the driven equipment (e.g., a pump or a fan), are not properly aligned with each other. There are several ways misalignment can occur between two shafts including angular, parallel and, if fitted with a rolling element bearing, the bearing could be misaligned with the shaft
Loose Structural Mounting (Soft Foot)	This can be caused by the structural looseness of machine mounting. Distortion of the base is likely to cause ‘soft foot’ problems
Mechanical Looseness	Mechanical looseness refers to a condition where the components of a motor system are not securely fastened or sufficiently connected
Rotor Rub	Rotor rub refers to a mechanical issue that occurs when the rotor (the rotating part of an electric motor) comes into contact with the stator (the stationary part of the motor). A rotor rub can occur in a radial direction at a seal, for example, or in the axial direction, due to uneven thermal growth between a turbine rotor and its casing. In any case, it is a rub, either through a complete shaft revolution or just during a part of a revolution, between rotating and stationary components.
Ball Bearing Fault	Common types of bearing ball faults in motors include: Ball Bearing Wear: Over time, the constant movement and friction within the bearing can cause wear and tear on the ball bearings. This wear may manifest as pitting, scoring, or general surface deterioration, ultimately leading to reduced bearing performance. Ball Bearing Spalling: Spalling occurs when small pieces of the bearing material break away, leaving behind rough or uneven surfaces. This can result from excessive loads, improper lubrication, or other factors that cause localized stress on the bearing balls. Bearing Ball Cracks: Cracks in bearing balls can be caused by a variety of factors, including overloading, improper installation, or manufacturing defects. Cracked balls can lead to increased friction and vibration within the bearing. Ball Bearing Misalignment: Misalignment of the bearing balls can result from factors such as shaft misalignment or excessive axial or radial loads. Misalignment can lead to uneven wear and increased stress on the balls.
Inner Race Bearing Fault	The inner race of a bearing is the part of the bearing that directly contacts and supports the motor shaft. Common types of inner race bearing faults in motors include: Inner Raceway Wear: Over time, the constant movement and friction within the bearing can cause wear and tear on the inner raceway. This wear may manifest as pitting, scoring, or general surface deterioration, ultimately leading to reduced bearing performance. Inner Raceway Cracking: Cracks in the inner raceway can be caused by factors such as overloading, improper installation, or manufacturing defects. Cracks can lead to increased stress concentrations and reduced bearing load-carrying capacity. Inner Raceway Fretting: Fretting refers to small-scale wear and corrosion that can occur at the contact interface between the inner race and the motor shaft. It often results from microscopic relative motion between the surfaces, which can lead to surface damage and pitting. Indentations or Bruising: Sudden impacts or heavy shock loads can cause indentations or bruising on the inner raceway. These physical deformations can lead to uneven loading and increased stress on the bearing.
Outer Race Bearing Fault	The outer race of a bearing is the part of the bearing that is stationary and typically housed in the motor's casing or housing. Common types of outer race bearing faults in motors include: Outer Raceway Wear: Over time, the constant movement and friction within the bearing can cause wear and tear on the outer raceway. This wear may manifest as pitting, scoring, or general surface deterioration, ultimately leading to reduced bearing performance. Outer Raceway Cracking: Cracks in the outer raceway can occur due to factors such as overloading, improper installation, or manufacturing defects. Cracks can lead to increased stress concentrations and reduced bearing load-carrying capacity. Outer Raceway Fretting: Fretting refers to small-scale wear and corrosion that can occur at the contact interface between the outer race and the bearing housing or casing. It often results from microscopic relative motion between the surfaces, which can lead to surface damage and pitting. Indentations or Bruising: Sudden impacts or heavy shock loads can cause indentations or bruising on the outer raceway. These physical deformations can lead to uneven loading and increased stress on the bearing.
Bearing Cage Fault	A bearing cage fault, refers to an issue that occurs within the bearing cage, also known as the bearing retainer or bearing separator, of a ball or roller bearing used in an electric motor. Common types of bearing cage faults in motors include: Cage Wear or Erosion: Over time, the constant movement and friction within the bearing can cause wear or erosion of the bearing cage material. This can lead to the misalignment or irregular positioning of rolling elements, affecting bearing performance. Cage Cracking or Fracture: The bearing cage can develop cracks or fractures due to factors such as excessive loads, shock loads, or manufacturing defects. Cracks in the cage can disrupt the proper functioning of the bearing by allowing the rolling elements to move irregularly. Cage Deformation: The bearing cage can become deformed or distorted due to high temperatures or overloading. Deformation can result in misalignment of the rolling elements, leading to increased friction and wear. Cage Jamming: In cases where debris or contamination enters the bearing, it can become lodged in the bearing cage, preventing the free movement of rolling elements. This can cause significant bearing issues and reduce motor performance.

Appendix A: First Principle Failure Modes

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