7 January, 2014
What is the difference between preventive and predictive maintenance? These two terms are often interchanged incorrectly; so an understanding of these 2 very different maintenance types can better help plan your maintenance strategy.
Preventive maintenance (also called planned maintenance or planned preventive maintenance) is driven by time, meter or event based triggering. Maintenance tasks that are undertaken during PM’s are pre-determined based on a number of factors including experience, age, manufacturers recommendations etc. It is assumed that a machine component will degrade within a time period that is common for its type. Under a preventive management approach, the relevant parts will be removed, replaced or rebuilt on or before the expected failure point. For example, your engine oil in your car is proactively replaced at 10,000 miles. Mean-time-between-failure (MTBF) statistics can determine help optimize preventive maintenance management schedule to include inspections, repairs and rebuilds.
The main issue with a preventive maintenance approach is that the way a machine is used, how often it is used, as well as a number of other variables, directly impact the operating life of the machine and its components. In many cases, parts are replaced when there is no need. Therefore, this approach can sometimes result in unnecessary maintenance. Unnecessary maintenance can become even more costly if the technician causes collateral damage during the replacement.
Predictive maintenance is determined by the condition of equipment rather average or expected life statistics. Essentially, this methodology tries to predict the failure before it actually happens by directly monitoring the machine during normal operating condition. In the car example above, rather than replacing the oil every 10,000 miles, using predictive maintenance methodology, oil samples are taken at regular intervals and the oil is replaced when it degrades beyond a certain point. This is called condition-based maintenance. In many cases, when predictive analysis spots an issue, the repair can be scheduled at a time that minimizes the impact on production.
A range of cost-effective tools can be used within a predictive maintenance program to analyze system performance and produce accurate factual data about pivotal systems, so that maintenance activities can be undertaken the moment they are needed. Improvements in quality, profitability and productivity can result when predictive maintenance is used on capital-intensive assets.
Effective Maintenance Management
Many businesses are surprised to learn that significant maintenance dollars can be saved through the use of effective maintenance management methods in the right places. The impact of random or inappropriate maintenance can certainly be felt in terms of the quality of products and services, operating costs and thus the bottom line so it makes sense to select the appropriate policy for each asset.
The great news for businesses is that Maintenance Assistant CMMS offers a way for a business to enhance the effectiveness of its maintenance procedures and processes. It can be used to track both preventive and predictive maintenance in one CMMS. For example, the scheduled maintenance time based trigger can be used to track time-based preventive maintenance or time based predictive inspections for CBM. In a recent post, Jeff O’Brien outlined how to integrate Condition Based Maintenance with MA CMMS. With the API under development and due for release in 2014, it will be possible to integrate systems directly with the CMMS so they can communicate directly.