Whati's MES?

Whati's MES?

        A manufacturing execution system (MES) is a control system for managing and monitoring work-in-process on a factory floor. An MES keeps track of all manufacturing information in real time, receiving up-to-the-minute data from robots, machine monitors and employees. Although manufacturing execution systems used to operate as self-contained systems, they are increasingly being integrated with enterprise resource planning (ERP) software suites. The goal of a manufacturing execution system is to improve productivity and reduce cycle-time, the total time to produce an order. By integrating an MES with ERP software, factory managers can be proactive about ensuring the delivery of quality products in a timely, cost-effective manner.

picture 1 show MES layer

Bridging the Gap

        Applying information technology to assist in the execution of production, through on-line management of the activities at the plant floor, has been a rapidly growing trend for a number of years. Planning systems have been applied under a variety of titles, including Material Requirements Planning (MRP), Manufacturing Resources Planning (MRPII), Enterprise Requirements Planning (ERP), and Manufacturing Control Systems (MCS). Also in place for many years are modern control systems that manage or control a machine’s functions such as PLCs used to run machine tools.

        The MES system bridges the gap between the planning system and the controlling system using on-line information to manage the current application of manufacturing resources: people, equipment and inventory.

       With direct electronic connections to the planning system and the equipment control systems, the MES is the hub that collects and provides information and direction within the production activities. To support on-line management decisions the MES usually includes direct connection to functions such as SPC,Time & Attendance, Product Data Management, Maintenance Management, and any other similar tool.

 Benefits 

              • Reduces manufacturing cycle time.                • Reduces or eliminates data entry time.

              • Reduces work-in-process inventory.              • Reduces lead times.

              • Reduces paperwork between shifts.               • Improves product quality.

              • Eliminates lost paperwork/blueprints.              • Empowers plant operations people.

              • Improves customer service.                           • Responds to unanticipated events.

          The potential gain by implementing MES addresses the need for immediate, current, on-line information that allows users or the MES computer system to make the best informed decisions regarding the application of inventory, plant resources, and people.

the core functions of the manufacturing execution system (MES)

        Planning System Interface   The MES should be directly coupled to the planning system to accept work orders and all other input and toprovide upload information as necessary. The communications should be two way so the MES can keepthe planning system properly informed about plant activities such as labor data, inventory changes, andwork order progress. Other methods of data entry and reporting can easily be accommodated, and in somecases, such as more continuous process, production orders may not be used at all.

        Work Orders  The MES accepts the Work Order through automatic or manual entry. It manages changes on orders,establishes and changes schedules, and maintains a prioritized sequenced plan. Releasing orders to production and establishing a current order priority list based on your sequencing rules is a normal part of MES. Frequently changes must be made to released orders. Within MES, order modifications such as these examples can be done easily:

               • Enter schedule changes                   • Mark for material shortage.

               • Enter quantity                                       • Place on hold.

               • Split orders or combine orders.

         Work Stations  This part of the system is responsible for implementing the direction of the Work Order plan and the logical configuration of the WorkStations. The planning, scheduling, and loading of each operational Work Station is done here, providing the current and total shop load by operation using routing data and time standards. Based on this plan, the system will request and manage delivery of inventory, tooling, and data in response to the Bill of Material requirements and will issue and execute commands to move the required items to the planned WorkStation. The MES can and should include the direct control interface and connection with each WorkStation.

        Inventory Tracking and Management  While the planning system has the aggregate data on inventory, the detail can easily reside at the locallevel the MES. “Dock To Stock” operations are accomplished here with regular updates to the planning system. A current map of all inventory and storage locations, including WIP, is maintained.

        Material Movement Another major area of MES system contribution is the movement of inventory or information to the needed location on the plant floor. This portion of the system controls material movement in the plant, in manual or automatic systems, by issuing requests for a manual move (printing move tickets) or issuing commands to material handling system control PLCs, such as ASRS, AGVS, conveyor systems, carrousels, robots, etc. The commands can be as simple as “move this item from this location to that location.”

         Data Collection This part of the MES system is the eyes and ears for management and gathers information so the system can remain current. Through various kinds of sensing devices and control interfaces, data from the floor operations can be collected, collated, and dispersed on whatever basis is desired. This is the primary method for all personnel to communicate with the MES, either through information input/output by system operators or recognition of events electronically. Direct connections with PLCs to download and/or collect information are also part of this function area.

        Exception Management The most custom portion of the MES is addressing how a company responds to plan exceptions. What happens when a WorkStation is suddenly down, or when material is not available, or when a Work Order becomes “hot”? The MES should be able to take these changes in stride and respond with alternative actions.

Our process began with a planned or sequenced list of Work Orders, methods to schedule those Work Orders into Work Stations, control of inventory assignment, and management of material movement. Along with data collection to keep the system current and a way to handle exceptions, we have the ability to execute the manufacturing plan truly a Manufacturing Execution System.