Preventive Maintenance

Preventive Maintenance According To Standards

Measures carried out intended to assess and/or to mitigate degradation and reduce the probability of failure of an object.

Preventive Maintenance can consist of CONDITION-BASED, PREDETERMINED, and PREDICTIVE measures.

Condition-Based Maintenance

• Preventive maintenance which include assessment of physical conditions, analysis and the possible measures.
• Control and monitoring of performance and characteristics can be scheduled, on request or continuous. Subjective or objective assessment.
  
  

Predetermined Maintenance

• Preventive measures carried out in accordance with established intervals of time
  or number of units of use, but without previous condition investigation
• This could be, cleaning, lubrication and replacement of components or spare parts.
  
  

Predicitve Maintenance

• Condition-based measures carried out following a forecast derived from repeated analysis or known characteristics and evaluation of the significant parameters of the degradation of the item

CONDITION-BASED MAINTENANCE

This is a method designed to acquire information about the condition of individual machines in order to identify the appropriate measure at an optimal time. Accordingly, condition-based measures requires the means to retrieve information about the condition of a machine. This usually involves various types of measurement techniques such as vibration measurement, thermography, ultrasonic measurement and oil analysis.

The condition-based process consists of five process steps; data collection, analysis, work order, corrective measure and function control.

Advantages

• Appropriate measures at the right time
• Scheduled measures instead of emergency actions
• Minor machinery defects are detected in good time and corrected
• Fewer emergency breakdowns due to worn parts
• High rate of skills development for technicians and electricians
• Knowledge of in-house machinery builds up within the organization

Disadvantages

• May entail high initial investment costs
• Risk of machinery being renovated too early
• Can be difficult to gain support for CBM throughout the organization

Predetermined Maintenance

Refers to preventive measures performed according to calendar schedule or operating time, e.g. the replacement of oil, belts, clutch discs and other wear parts. The term also includes scheduled overhauls where machinery and components are taken apart for inspection.

Advantages

• Reduced risk of emergency breakdowns
• Improved availability
• Increases degree of planning for the upkeep operation
• Development of staff competence
• Reduced costs
  
  

Disadvantages

• Costs for unnecessary spare parts and working hours
• Risk of machinery being “maintained” to excess
• Unnecessary downtime costs
• Often static planning with limited feedback of experience to the actual plan

Predicitve Maintenance

According to the standard, predictive measures involves identifying a fault during its development period. It is a form of condition-based maintenance. With today’s technology, there is usually some kind of smart monitoring system that analyzes and processes the measurement data. This makes it easier to e.g. determine when it’s time to replace a bearing or the oil in a unit.

The predictive measures principle can naturally also be used with recurring condition monitoring, such as visual inspections or collecting measurement data for subsequent analysis and a decision on scheduled, predictive maintenance.

The purpose of predictive measures is simply to forecast the best time to e.g., replace a unit in order to exploit its full service life.