What is MES ?

Manufacturing Execution Systems (MES) are computerized systems used in manufacturing. MES can provide the right information at the right time and show the manufacturing decision maker "how the current conditions on the plant floor can be optimized to improve production output.

MES work in real time to enable the control of multiple elements of the production process (e.g. inputs, personnel, machines and support services).

MES might operate across multiple function areas, for example: management of product definitions across the product life-cycle, resource scheduling, order execution and dispatch, production analysis for Overall Equipment Effectiveness (OEE), and materials track and trace.

The idea of MES might be seen as an intermediate step between, on the one hand, an Enterprise Resource Planning (ERP) system, and a Supervisory Control and Data Acquisition (SCADA) or process control system on the other; although historically, exact boundaries have fluctuated.


Manufacturing Execution Systems create flawless manufacturing processes and provide real-time feedback of requirement changes, and provide information at a single source. Other benefits from successful MES implementation might include:

  1. Reduced waste, re-work and scrap, including quicker setup times
  2. More accurate capture of cost-information (e.g. labor, scrap, downtime, and tooling)
  3. Increased uptime
  4. Incorporate Paperless Workflow Activities
  5. Reduced inventory, through the eradication of just-in-case inventory

Functional areas

Over the years, international standards and models have refined the scope of such systems in terms of activities, that typically include:

A functional hierarchy was defined in which MES were situated at Level 3 between ERP at Level 4 and process control at Levels 0, 1, 2. Activities in Level 3 were divided over four main operations: production, quality, logistics and maintenance.

  • Management of product definitions. This may include storage, version control and exchange with other systems of master data like product production rules, bill of material, bill of resources, process set points and recipe data all focused on defining how to make a product. Management of product definitions can be part of Product lifecycle management.
  • Management of resources. This may include registration, exchange and analysis of resource information, aiming to prepare and execute production orders with resources of the right capabilities and availability. Scheduling (production processes). These activities determine the production schedule as a collection of work orders to meet the production requirements, typically received from Enterprise resource planning or specialized Advanced planning and scheduling systems, making optimal use of local resources.
  • Dispatching production orders. depending on the type of production processes this may include further distribution of batches, runs and work orders, issuing these to work centers and adjustment to unanticipated conditions.
  • Execution of production orders. Although actual execution is done by Process control systems, an MES may perform checks on resources and inform other systems about the progress of production processes.
  • Collection of production data. This includes collection, storage and exchange of process data, equipment status, material lot information and production logs in either a data historian or relational database.
  • Production performance analysis. Create useful information out of the raw collected data about the current status of production, like Work In Progress (WIP) overviews, and the production performance of the past period like the Overall Equipment Effectiveness or any other Performance indicator.
  • Production Track & Trace. Registration and retrieval of related information in order to present a complete history of lots, orders or equipment (particularly important in health related productions, e.g. pharmaceuticals).


In the early 1980s, MES concepts originated from data collection systems. A wide variety of systems arose using collected data for a dedicated purpose. Further development of these systems during the 1990s introduced overlap in functionality. Then the Manufacturing Enterprise Solutions Association (MESA) introduced some structure by defining 11 functions that set the scope of MES. In 2000, the ANSI/ISA-95 standard merged this model with the Purdue Reference Model (PRM).

A functional hierarchy was defined in which MES were situated at Level 3 between ERP at Level 4 and process control at Levels 0, 1, 2. Activities in Level 3 were divided over four main operations: production, quality, logistics and maintenance.

Additional parts of the ANSI/ISA-95 standard defined the architecture of an MES into more detail, covering how to internally distribute functionality and what information to exchange internally as well as externally.