It is important for companies to set up maintenance procedures according to their activity and the capital goods implemented in the framework of their activity. Maintenance is an essential process that has a strong impact on the results of a production company. There are various types of maintenance that can be put in place depending on the risks, the principles of which are as follows:
Corrective maintenance aims at intervening following the malfunction of a system. It is the worst situation for a production tool. These malfunctions and breakdowns generate significant costs for the company. Corrective maintenance mobilizes resources to intervene at any time, and requires a multidisciplinary team that can intervene quickly. It induces production losses linked to the partial or complete stoppage of the production tool. This type of maintenance requires a large stock of spare parts, which can quickly be depreciated if not properly managed. This type of maintenance remains very suitable for simple systems that are not subject to much stress or have a low impact on a company's operations.
One of the possible areas of improvement for this type of corrective maintenance is the implementation of systems ingeniously designed for rapid maintenance or replacement of the defective component. It is common for the machine operator to perform some of these corrective interventions. The intervention times and costs inherent in corrective maintenance can be drastically reduced by implementing other types of maintenance such as preventive maintenance. As already mentioned, these maintenance procedures must be adapted to the operation of the company and the production tools.
Systematic maintenance is part of so-called preventive maintenance. It is carried out systematically according to a time parameter, a number of cycles or a number of products produced. Systematic maintenance makes possible to significantly reduce the number of breakdowns and malfunctions of the production tool. The implementation of systematic maintenance is easy and based on the characteristics of the components that make up the system. It is this type of systematic maintenance that is generally carried out on safety systems that require periodic systematic checks. The main drawback of systematic maintenance is that its effectiveness decreases over time because its principle does not take into account the ageing of the equipment. The improvement of its efficiency requires the implementation of conditional maintenance procedures.
Conditional or predictive maintenance corresponds to maintenance implemented on the basis of analysis of the signs indicating a deterioration in the operation of a system. By carrying out checks and observations using specific tools it is possible to predict the maintenance interventions of a system before failure. The objective is to limit unplanned interventions during periods of production or high mobilization of production equipment. Conditional maintenance requires to take into account different system behavior such as vibrations, noise, temperature, dimensional variations. The effectiveness of a conditional maintenance procedure will directly depend on the relevance of the parameters measured and their number.
Failure Mode, Effects and Criticality Analysis (FMECA) is a good method for the implementation of conditional maintenance procedures.
Maintenance operations are then planned in order to optimize their number. Relatively difficult to implement, conditional maintenance requires significant feedback on the operation of the systems on which it will be applied. On the other hand, once the inspection points and frequencies have been defined, conditional maintenance allows for easy monitoring and makes a significant contribution to reducing the failure rate of capital goods.
Predictive maintenance is based on the continuous observation of equipment and its behavior. Established according to the same processes as conditional maintenance, it allows maintenance interventions to be planned with great precision, avoiding breakdowns as well as optimizing the number of interventions.
The difficulty lies in interpreting the signs of fatigue and knowing how to quantify them in order to continuously adapt the intervention schedule according to their evolution and their behavior.
For this type of maintenance there are sensors interfaced with software integrating artificial intelligence. These sensors are installed on the sensitive components of a system and allow to monitor the equipment, to measure the evolution of their wear and tear and to alert in case of risk. The predictive maintenance plan evolves with the life span of the system and its use.
Regardless of the type of maintenance implemented, the intervention teams must be aware of the existence of the procedures in place and have access to them. The documents must precisely describe the various control points and the means to be implemented to carry out the intervention. There are many reasons for setting up maintenance procedures, whether they are only corrective or more preventive. The analyses that are thus carried out when a maintenance procedure is set up make it possible to improve the operation of capital goods, on the one hand by increasing their reliability and on the other hand by optimising intervention times, for example by making modifications to facilitate the replacement of a wearing part.
The benefits can be quickly and clearly measured in productivity and efficiency gains. More discrete and no less impacting on a company's result, other benefits appear such as gains in energy consumption, a reduction in waste, a limitation of spare part stocks.
It is important to address the maintenance aspects of a system from the design stage by selecting the various components according to the constraints they will undergo, their compatibility with each other, the simplicity of their design and of course their reliability.
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