The purpose of preventative maintenance is to avoid the costly impact of unscheduled downtime should machine components fail. In many cases the components replaced may still be within specification, but we replace them anyway rather than take the risk – especially where the equipment is critical to output.
An accusation regularly levelled at this approach is that it can lead to excessive maintenance. Operators would much prefer to know when a machine part is going to fail, so they can avoid carrying out the work until it is absolutely necessary. Ideally, this would be the exact remaining lifetime of the component, but predictive maintenance technology is some way off achieving that level of precision.
What we tend to see happening currently, when it comes to critical machinery, is a condition-based approach to maintenance that involves the deployment of condition-monitoring solutions which rely on sensors to detect signs a component could be deteriorating...