Maintenance within the industry has undergone a significant evolution, largely driven by advancements in control and measurement technology. This chapter provides a summary of this evolution, detailing four stages of maintenance.
In the beginning, maintenance was only carried out as a result of breakdowns, resulting in repair costs, downtime and other associated expenses. This approach is referred to as corrective maintenance.

Figure 1.1: Maintenance strategies

As a result of the need to reduce costs due to low availability of machinery and consequent production downtime, maintenance technicians began scheduling periodic inspections to keep machines in the best possible condition and reduce the likelihood of failure. However, this technique, known as preventive maintenance, is uncertain in terms of cost and raises questions such as the appropriateness of established maintenance intervals and the potential for reducing them without negative consequences for the machinery. These uncertainties limit the effectiveness of maintenance.

With the support of technological development, a new maintenance concept was developed based on the condition or state of the machine. This approach is known as predictive maintenance. It is based on anticipating failure by means of knowledge of how the machine behaves and how it is supposed to do so, allowing for an intervention to be scheduled without affecting the production process, thus optimizing production costs, labor and spare parts. This approach allows for the avoidance of large, costly catastrophic faults and results in shorter intervention durations.

Proactive maintenance has been developed as a complement to the evolution of predictive maintenance. While predictive maintenance can determine if any machine component is likely to fail, it does not study the root cause of the failure. Proactive maintenance addresses this uncertainty by analyzing the root cause of repeat faults and solving the related technical aspects, such as inadequate machine components.

Figure 1.2: Proactive maintenance