Types of Corrective Maintenance

Corrective Maintenance (CM) is a type of maintenance strategy that is generally required for restoring any assets after its failure or breakdown. Restoring can be done by either repairing, replacing, readjusting, etc. There are many objectives of CM but its main objective is to correct and bring back broken or failed assets to its normal working condition. CM is mostly applicable to assets that are not crucial to running of functions and operations. Types of Corrective Maintenance : CM is generally classified into two different categories as given below :

1. Planned Corrective Maintenance : Planned CM, as name suggests, is a type of CM that is planned and can be performed later. Therefore, Planned CM is also known as Scheduled CM or Deferred CM. It is a type of CM is that essential and needed to be performed but not immediately just after asset failure. It can be performed later. Planned CM is usually performed for assets that are not critical or are less critical i.e. have very little impact on overall system after its failure. Such type of assets failure is tolerable and are easy to be restored, repaired, or replaced as well as are cost-effective also. Planned CM is further divided into two different categories on basis of which CM is considered planned :
   • Run-to-Failure (RTF) Maintenance - For such CM, RTF maintenance strategy is generally used in which asset is allowed to run until its failure and is then repaired or replaced to bring it back to normal working condition.
   • Preventive Maintenance (PM) - Preventive maintenance strategy can be used as a part of CM in which problems or issues have usually identified that lead to failure of assets. In this, issue is determined before it leads to equipment failure and if any issue is found, then corrective maintenance can be planned and scheduled.
   
   There are other reasons also due to which corrective maintenance is considered planned or deferred :
   • Unavailability of replacement parts or resources required to perform CM.
   • Unavailability of specialists at present required to perform CM.
   • Technicians are required for higher severe cases.


2. Unplanned Corrective Maintenance : Unplanned CM, as name suggests, is a type of CM that is unplanned and needed to perform immediately after asset failure. Therefore, Unplanned CM is also known as Unscheduled CM or Immediate CM. It is a type of CM is that essential and needed to be performed but not too later after asset failure. It is needed to perform immediately just after asset failure. CM is usually performed for assets that are very critical i.e. have greater impact on overall system after its failure. Such type of assets failure is tolerable and are easy to be restored, repaired, or replaced as well as are cost-effective also.
   Unplanned CM is further divided into two different situations on basis of which CM is considered unplanned :
   • There are several cases, in which preventive maintenance is applied but then too failure occurs somehow in between planned maintenance actions. Therefore, CM required in such situations is considered to be unplanned as asset failure is immediately required to be repaired or replaced because it can be critical and can affect production and overall system at greater cost. CM can be costly also in such situations and is performed depending upon availability of resources, tools, parts, etc. that are required to repair or replace failed assets.
   • In other cases, assets can be failed unexpectedly without any sign of potential failure or chances of failure occurrence. In such cases also, CM applied is considered to be unplanned as there is no planned maintenance strategy applied to address failed assets.