Companies know how their productivity partly depends on their industrial maintenance processes. Each company has very precise needs and therefore has to implement a specific type of maintenance.
Importance of Maintenance in Business
Many industries can confirm how maintenance costs represent a high share of operating costs. Figures obviously vary from one company to another but they can still sometimes represent up to 50% of the global production costs, without even taking into account planned or unplanned downtime, stock and tools management, purchasing… There are as many unforeseen events which can lead to additional costs that a company often struggles to estimate but that are nonetheless closely linked to the maintenance teams’ activity. It goes without saying that an organization’s profitability and productivity partly depend on the maintenance processes that have been implemented.
In order to help you make the right decision and deploy the perfect strategy, we want to discuss the different types of industrial maintenance, its application, when such maintenance is required and one of the many maintenance priority differentiation methods.
Types of Maintenance
The various types of maintenance that follow, however, can be applied in any combination within an organization.
Preventive Maintenance, PM ( Planned Preventive, Planned, Scheduled)-
Preventive maintenance is maintenance performed with the intent of avoiding failures, safety violations, unnecessary production costs and losses, and to conserve original materials of fabrication. The effectiveness of a preventive maintenance schedule depends on the RCM analysis which it was based on, and the ground rules used for cost efficacy.
Can be time-based or condition-based. As the terms imply, these methods define schedules either based on a set period of time (e.g. every 30 days) or on a specified condition (e.g. every 500 hours ran). Most PM plans include both methods.
When to apply-
Most critical assets should have a PM plan, because assets that break down more often and more catastrophically will benefit the most from regular, inexpensive maintenance activities. Lower frequency of breakdowns means less downtime and overtime costs, extended equipment lifetime, increased production efficiency, and increased maintenance team productivity .
Predictive Maintenance (PdM)-
More recently, advances in sensing and computing technology have given rise to predictive maintenance . This maintenance strategy uses sensors to monitor key parameters within a machine or system, and uses this data in conjunction with analysed historical trends to continuously evaluate the system health and predict a breakdown before it happens. This strategy allows maintenance to be performed more efficiently, since more up-to-date data is obtained about how close the product is to failure.
Predictive maintenance is really only condition-based, but with more precision. Instead of performing maintenance tasks after a certain number of hours ran, for example, thresholds can be vibration rates, temperature, or pressure. This often requires sophisticated sensors to monitor conditions, which can be continuous or periodic. Industrial Internet of Things (IIoT) plays a big role in PdM.
When to apply-
PdM can be a very effective maintenance method in the right situation. A predictive maintenance plan is usually more relevant with more precise data on causes of breakdowns and inefficiency. This strategy can require expensive monitoring equipment, but its implementation can save money in the long run.
Corrective Maintenance (RM, or Breakdown, Run-to-Failure, Reactive)-
Corrective maintenance is a type of maintenance used for equipment after equipment break down or malfunction is often most expensive – not only can worn equipment damage other parts and cause multiple damage, but consequential repair and replacement costs and loss of revenues due to down time during overhaul can be significant. Rebuilding and resurfacing of equipment and infrastructure damaged by erosion and corrosion as part of corrective or preventive maintenance programmes involves conventional processes such as welding and metal flame spraying, as well as engineered solutions with thermoset polymeric materials.
Reactive maintenance can be immediate or deferred. For assets that significantly hinder operations, immediate action should be taken. However, breakdowns on less-critical equipment may sometimes be deferred until resources are available.
When to apply-
RM is typically most effective on non-critical assets. This is because a low cost of replacement/repair on these assets, as well as a low probability of failure don’t merit the costs of more frequent PM or of monitoring equipment required for PdM. Reactive maintenance is free to set up, but the higher frequency of breakdowns becomes expensive to apply for critical asset
One way of differentiating maintenance priority between assets is as follows: Asset Criticality Value = (probability of failure) x (consequences of failure) .Assets with a higher criticality value should receive more maintenance resources. Since we can assume that all companies have the goal of operational reliability and are faced with limited resources, reliability-centered maintenance and risk-based maintenance should both be generally-accepted practices.
In conclusion, most organizations use some combination of preventive, predictive, and reactive maintenance as their maintenance strategy. A maintenance plan should carefully consider the needs of the company and the criticality of each asset.
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