Surprisingly, many companies still use a system of Planned PeriodicMaintenancein an attempt to avoid costly downtime arising from the failure of their equipmentand machinery. In other words, they replace parts that tend to wear out(e.g. motor bearings) on a routine basis whether they need replacing or not.Not only is this needlessly costly, but can make matters worse by introducing faults during the process of stripping down and rebuilding a perfectly good machine. Even more of a problem is deciding the PPM time intervals. Too frequent,means more wasted time and cost (and morepotential for introducing faults) but not frequent enough, means more unexpected breakdowns.
Condition Based Maintenancerelies on the fact that a machine’s condition (degree of wear) can be monitored, by measuring the vibration levels in motor bearingsfor example. This way,the machine only needs to be maintainedwhen its condition deteriorates beyond an acceptable level. This decision isbased on recording and tracking changes in the machine’s condition over time (trending).Put simply, CBMphilosophy isif it’s not broken, don’t try to fix it!
This approach obviously saves time and money since machineparts are only changed when they need to be. However,CBM can potentially save a lot of money by spotting a machinethat is about to fail prematurelybefore it fails and hence avoid an unexpected and costly shutdown.
Clearly, CBM is a superior technique but until now,its cost of implementation has put off some companies from using it. Traditionally, both CBMequipment and the expertise required to use it has been prohibitively expensive.
Test Products International (TPI) has however completely revolutionised this concept with the introduction ofits low cost, portable vibration analysers and free to use trending software. Both the analysers and software arevery easy to use,stemming from the fact that they are very intuitive and based on internationally agreed (ISO) alarm levels for rotating machinery.
TPI’s free to use VibTrend machine management and trending software stores machine condition readings and displays their trends in a clearand easily understood graphical format. In addition, various ‘expert system’ features are incorporated into the software, such as bearing quality assessment, which is achieved by analysing the frequency components of the vibration data and automatically identifying the classic ‘signatures’ associated with bearing wear. That way,it is very easy to monitor the health of a bearing simply by observing the level ofbearing quality displayedon the trend plots.
A complete CBM system can cost from as little as £1,450 with the TPI 9080, whichuses industry standard accelerometers and offers on-meter analysis for the detection of machine faults such as unbalance, misalignment, looseness and bearing wear. Theequivalent intrinsically safe version (IEC Ex, ATEX and North American)TPI 9080Exoffers a complete Zone 1 CBM solution for £3,500. Both versions include a full VibTrendfree to use unlimited software license.