During my professional career, I have worked with two different types of software applications for plant maintenance. My first experience was with Enterprise Asset Management systems. At Andea, I was introduced to a new way of managing maintenance tasks using Manufacturing Execution Systems. First, we shall cover some plant maintenance basics by outlining what negative influence improper asset maintenance can have on production. When the equipment in your factory gets older, the risk of serious failure increases. Each failure causes downtimes and decreases production rates, which can have a negative impact on company’s financial results. To minimize this impact, the time spent on fixing a broken machine should be as short as possible. This can be partially done by collecting all necessary data about machine state before a breakdown and making that data available for the maintenance team, which in turn can help them to be more effective. The number of equipment failures can be also decreased by applying correct preventive maintenance rules. Having one system collect, store and manage all this data can be very advantageous.
EAM systems offer a large variety of modules that provide an ability to manage all maintenance process. This includes all inventory data for assets and its spare parts as well as purchasing and financial information. The most valuable part of the system is the ability to manage preventive maintenance and service request (SR). These functions support proactive and reactive maintenance respectively. However, preventive maintenance module is used to create work schedules that repeat themselves in a given time. Both approaches differ in how the work is managed. In case of preventive maintenance, there is a work order created in advance with a start date placed in the future. For SR, there is one primary work order that consists of other work order activities with a parent-child relationship. In both cases, there is no difference in how further steps are managed. For each work order, an allocation of materials, labor and tools is done. This is the point where financial processes start. Purchase requests for materials and services have to be created. After approval, these purchase requests are converted into purchase orders against which invoices can be generated. This approach allows for fast reaction to unexpected events as well as provides a framework to prevent aging machines from breaking down by maintaining them early enough. While the equipment is getting older, the frequency of preventive maintenance tasks can be increased to reduce the likelihood of a breakdown.
In an MES system, the approach is similar. It allows to schedule preventive maintenance actions for any factory equipment and can also be used for reactive maintenance. This functionality is connected with MES most basic function. MES can be integrated with plant equipment. This gives the system access to data such as number of items produced and quality of those goods. To provide a real life example, imagine a machine that cuts large sheets of metal into pieces. The most common way to create a trigger for a preventive maintenance task is to define:
- a time window during which the machine was operating,
- a number of pieces it cut,
- or a combination of both.
Because an MES system can have access to machine data, it can act in near real-time on these preventive maintenance triggers. In addition to that, in MES a maintenance order can be defined when something unexpected has happened. For example, there could be a problem when the metal cutting machine starts to produce a thicker sheet of metal than usual. Standard blade used for cutting might not be strong enough for the thicker material, which can cause it to break and create a downtime for the machine. To prevent such a scenario, MES can be configured to schedule a maintenance order once the system receives information that parameter containing thickness exceeds the given limit. Replacing a blade prior to it actually breaking can help save a lot of time and unwanted headaches.
The main drawback of EAM applications is that they usually don’t take advantage of shopfloor data. If they do, integrating that data with EAM is not a trivial task. This is because EAM solutions are not designed to handle low-level PLC or SCADA data. Whereas the ability to handle such data is in MES systems’ DNA. This is why in MY opinion, MES offers a more sophisticated approach to plant maintenance than EAM applications… Thanks and I hope you enjoyed my blog.