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Choosing the Right Maintenance strategy

The cost of maintenance is seen as a necessary premium that must be paid as insurance for asset/equipment reliability. Consequently, the expenditure on all maintenance activity should ensure maximum return on that investment, through improved reliability and higher productivity. Unfortunately, it is rarely the focus point in many organizations. The primary focus of maintenance remains on returning a machine to production as quickly as possible without any significant effort made to improve the equipment reliability while the opportunity exists. This highlights an important concept in maintenance excellence about choosing the right maintenance strategy with respect to maintenance expenditure that can boost profitability.

Reactive Maintenance: Also known as breakdown maintenance, the basis of reactive maintenance is simple – fix when it breaks. We cannot plan these repairs, and hence this strategy best suits assets that are less complex and not essential for operations or have a low cost involved. However, an untimely asset breakdown could lead to an extended duration of downtime as well as significantly high repair cost.

Preventive Maintenance: As asset complexity increases, a time-based inspection and maintenance plan is put in place. Preventive Maintenance is the most widely used strategy that helps in extending asset life and in reducing breakdowns. On the flip side, it becomes critical to regularly monitor and audit the PM activities, because in many cases technical people often ignore tasks or spend too much time on the activity, resulting in higher time and cost of maintenance.

Predictive Maintenance: Use of sensors and digital technology provides high quality data that makes it possible to predict the risk of asset failure and conduct maintenance just at the right time. It is condition-based maintenance carried out following a forecast derived from the analysis and evaluation of significant parameters of asset degradation. The cost of deploying technological tools for predictive maintenance can be quite high, as it involves significant capital expenditure.

Figure below summarizes the three maintenance strategies discussed.

Aligning Maintenance Strategy with Asset Criticality

Asset failure is a common cause of concern at plants; particularly for those asset-sensitive industries having thousands of pieces of process and utility equipment that are prone to wear, deterioration, breakdown etc. This large volume of equipment results in dozens of maintenance work orders on a daily basis; causing extreme pressure on the maintenance teams. The most commonly used tools for prioritizing asset maintenance are the ABC Classification of equipment and conducting Failure Mode and Effect Criticality Analysis (FMECA) for analysing and correcting asset failure. In modern maintenance, even more critical than asset failure is the consequence and impact of failure. The previously mentioned tools enable classification of the equipment/component by the degree of criticality measured against the consequences and the impact of the failure.

A good practice widely assimilated in discrete manufacturing environments is the concept of Autonomous Maintenance or Operator Care. At its core, it aims to establish ownership at operator level for “their” assets. The effect of involving the shop floor, e.g. in cleaning and inspection routines is, in part, that maintenance spend can be reduced. However, the main impact is a mindset change of the operators, based on a better understanding of the technicalities of the process and also of being more aware of signals which indicate technical risk. Summing it all up, it is important to align the maintenance strategy (incl. spare parts policy etc.) with the criticality level of the equipment/components, as summarized below: