L8

• Equipment Failure


  Any event in which equipment cannot accomplish its intended purpose or task, equipment stopped working, equipment not performing as desired, or equipment not meeting target expectations
• Equipment Failure


  • Engine failure or misfire
  • Brake failure or stop controlling device failure
  • Suspension of operation due to heat or other environmental conditions
  • Failure due to defect in the electronics or circuits
  • Power failure or fuel supply failure
• Principal Causes of Failure in Machinery

  • Accidents
  • Inadequate maintenance
  • Corrosion
  • Misalignment
  • Bearing failure
  • Metal fatigue
  • Unbalance
  • Bent Shaft
• Accidents


  A piece of machinery being handled or operated in an incorrect manner can lead to internal parts becoming damaged and causing failure
• Inadequate maintenance


  Inadequate maintenance or a lack of maintenance can result in accidents occurring with machinery and equipment ultimately breaking down
• Corrosion


  Corrosion of vital industrial parts, such as couplings and Worm gearboxes, is one of the most common causes of equipment failing, especially when the machinery is exposed to water contamination
• Misalignment


  Misalignment exists when the centre lines of two adjacent machines deviate from each other. Misalignment is universally recognized as the leading contributor to machinery failure
• Principal Causes of Misalignment

  • Lack of appropriate Standards and Specifications
  • Poor Tolerances and Poor Methods
  • Good Methods, but bad practices
  • Lack of understanding of precision process
  • Dynamic movement (thermal growth, pipe strain etc.)
  • Mis-diagnosis with Unbalance or Looseness
• Most prevalent causes of misalignment

  • Bent shafts
  • Burrs or dirt on shaft or housing shoulders, shaft threads that are not square with shaft seats
  • Locking nuts with faces that are not square to the thread axis
• Bearing failure


  The local compression in front of the hole and often results in the out-of-plane buckling of materials around the hole. If bearings fail so too can the equipment you are operating
• Principal Causes of Bearing Failure

  • Loss, contamination or wrong type of lubricant
  • Mechanical defects such as misalignment, overload, overspeed and unbalance
  • Improper installation
• Metal fatigue


  A weakened condition induced in metal parts of machines, vehicles, or structures by repeated stresses or loadings, ultimately resulting in fracture under a stress much weaker than that necessary to cause fracture in a single application
• To help prevent machinery failure and the stress and loss of earnings equipment breakdown typically creates, it is important to keep machinery and internal parts well lubricated, well maintained, have parts regularly replaced, keep it stored in an appropriate place and only operated by those trained to do so
• Unbalance


  Unbalance exists when the mass centre line of a rotor is not coincident with the geometric centre line. The resultant orbital motion has a severe impact on the life of bearings and on seals
• Principal Causes of Unbalance

  • Accumulation of assembly tolerances
  • Poor attention to assembly
  • Inappropriate use of standards
  • Non-homogeneous materials (casting blow holes)
  • Operational – uneven build up of product
  • Erosion of rotor material
• Bent Shaft


  Shafts may become bent by being subject to an excessive force from unbalance, seizure or thermal distortion. This may also occur through poor assembly from cocked bearings, incorrectly torqued Taper Lock bushings, or tapered distance pieces
• Vehicle maintenance not on regular basis

  • A broken coupling that connects the drive shaft and driven shaft of a motor
  • Humming sound or grinding noise when car change lanes
  • Due to undergoing cyclic loading, a bolt initially start with a small crack & later on it broke into two pieces
• Failure Characteristics Curves


  • Pattern A - Bathtub Curve
  • Pattern B - Wear Out Curve
  • Pattern C - Fatigue Curve
  • Pattern D - Initial Break In Curve
  • Pattern E - Random Pattern
  • Pattern F - Infant Mortality
• Bathtub Curve


  Failure Pattern A is known as the bathtub curve and has a high probability of failure when the equipment is new, followed by a low level of random failures, and followed by a sharp increase in failures at the end of its life. This pattern accounts for approximately 4% of failures
• Wear Out Curve


  Failure Pattern B is known as the wear out curve consists of a low level of random failures, followed by a sharp increase in failures at the end of its life. The pattern accounts for approximately 2% of failures
• Fatigue Curve


  Failure Pattern C is known as the fatigue curve and is characterized by a gradually increasing level of failures over the course of the equipment's life. This pattern accounts for approximately 5% of failures
• Initial Break In Curve

  Failure Pattern D is known as the initial break in curve and starts off with a very low level of failure followed by a sharp rise to a constant level. This pattern accounts for approximately 7% of failures
• Random Pattern


  Failure Pattern E is known as the random pattern and is a consistent level of random failures over the life of the equipment with no pronounced increases or decreased related to the life of the equipment. This pattern accounts for approximately 11% of failures
• Infant Mortality


  Failure Pattern F is known as the infant mortality curve and shows a high initial failure rate followed by a random level of failures. This pattern accounts for 68% of failures
• Three distinct classes of machine failure have been observed: Infant mortality, random failures, and wear-out failures
• Infant mortality (early failures)


  Due to faulty material and faulty processing, installation, and/or operator training on new equipment. The failure of new slightly used components, is usually the result of inadequate lubrication, defects in materials workmanship, or substandard maintenance
• Oil analysis usually provides little in the way of predicting damage that results from substandard materials or manufacturing procedures. And it does not often alert operators of improperly installed components
• While oil monitoring may catch some substandard components or improperly installed components before failure, many of these defects need to be fixed at the source. Reliability analysis and non-destructive inspection should identify many of the material defects
• Infant mortality


  The failure of new slightly used components, usually due to inadequate lubrication, defects in materials workmanship, or substandard maintenance
• Some problems caused by substandard components or incorrect installation do provide an indication of distress that can be detected by oil monitoring prior to failure
• While oil monitoring may catch some substandard components or improperly installed components before failure, many of these defects need to be fixed at the source. Reliability analysis and non-destructive inspection should identify many of the material defects that would ordinarily result in early failure
• Constant failure rate (Random failures)

  Random failures that have a constant rate of failure
• Random failures


  Random failures occur relatively infrequently during the normal service life of a machine and are usually related to deterioration of a component as a result of poor materials, lubrication, maintenance practices, or improper machine operation
• Causes of random failures


  • Ingress contamination (water, fuel, dirt, etc)
  • Inadequate lubrication (insufficient or wrong oil)
  • Substandard lubricant quality (oxidation, degradation, etc)
  • Abnormal wear (substandard components, misalignment, unbalance, misuse)
• Many equipment failures can be prevented by more effective maintenance management. This includes a better understanding of the effectiveness of the various methods of machinery monitoring, and integration of equipment monitoring into the maintenance program
• Many organizations continue to operate their equipment monitoring function (oil, vibration, performance, reliability) independently of each other and independent of maintenance functions. This creates a competitive, sometimes adversarial, working environment with little exchange of data and ideas. The competition does not further the cause of maintenance management, improve maintenance economy or save jobs
• Wear-out failures (Time dependent failures)

  Failures due to aging, fatigue and so on
• Instantaneous time dependent failures


  • Usually exhibit some indication of deterioration prior to failure (e.g. erosion, corrosion, fretting, spalling, creep, cracking, pitting, leaking, abnormal noise or vibration, etc.)
  • Time dependency and effect of varying equipment utilization suggest these failure modes are better controlled by equipment monitoring
• Time dependent failures


  • Data acquired by real time or periodic sampling can be used to define the criteria for assessing component condition and the necessity for replacement or repair prior to failure
  • Can be viewed as either usage based failures (life limited) or condition based
• Usage based failures (life limited)


  Usage measurements such as operating hours, time at power, thermal or fatigue cycles, etc. are used to define the safe life limits for those components which are prone to instantaneous failures