In the present manufacturing paradigm, manufacturing execution systems (MESs) play a significant role in effective manufacturing management. Offered software solutions simultaneously close the gap between Enterprise Resource Planning (ERP) systems and production equipment control or SCADA (Supervisory Control and Data Acquisition) applications. Current ERP systems usually contain modules for material management, accounting, human resource management and all other functions that support business operations. In the past years, the role of ERP has been extended to cross-organizational coordination. Nowadays, as optimization of production activities is increasingly topical, a cooperation of ERP and MES becomes a serious concern of manufacturing managers.
Background Of Erp And Mes Evolution
From a historical perspective, the infiltration of information technology into manufacturing technology was conditioned by the development and advancement of host mainframe computing in the 1950s and 1960s. It gave manufacturers the ability to capture, manipulate, and share information and automate calculation and analysis in order to support design of increasingly complex and capable products. Simultaneously, in the framework of manufacturing management, an inventory control took on great importance and most of the software in the 1960s was developed for this purpose. Typically, inventory control was handled by a tool called BOM (bill of materials) processors, which were used as a means to represent process plans. The focus shifted in the 1970s to Material Requirement Planning (MRP) as the complexity of manufacturing operations increased. This managerial instrument enabled financial managers both to view and control their business processes much more closely. The tools to automate business processes were enhanced by adding further functionalities to meet the increased requirements. Subsequently, in the 1980s the term Manufacturing Resources Planning (MRP II) became popular. An MRP II presented extension of MRP functions to achieve integration of all aspects of the planning and control of the personnel, materials and machines (Kimble & McLoughlin, 1995). Following, solutions that are marked by acronym ERP were performed in the early 1990s. An ERP system can be defined as an integrated information processing system supporting various business processes such as finance, distribution, human resources and manufacturing (Choi & Kim, 2002). The newest version ERP II has been much publicized by the Gartner group (Mohamed & Fadlalla, 2005). Fundamentally, ERP II signals a shift in traditional ERP applications from focusing on internal data gathering and management process information to partners, vendors and customers externally via the Web (Farver, 2002). The overall view on evolution of ERP system is shown in Figure 1. Initially, this concept attained a huge popularity among manufacturers, but as the scope of managed systems increased, the ERP system was not suitable for controlling activities on the shop floor level. For this purpose, a new tool of manufacturing management called Manufacturing Executive System was evolved and utilized during the 1990s. There is more interpretation of MES depending on different manufacturing conditions, but the common characteristic to all is that an MES aims to provide an interface between an ERP system and shop floor controllers by supporting various “execution” activities such as scheduling, order release, quality control, and data acquisition (MESA #6, 1997). In a context of the MES development and deployment, it is important to point out that Manufacturing Execution Systems were originally designed to provide first-line supervision management with a visibility tool to manage work orders and workstation assignments. Consecutively, MES expanded into the indispensable link between the full range of enterprise stakeholders and the real-time events occurring in production and logistics processes across the extended value chain (McClellan, 2004).
The evolution of ERP systems
Key Terms in this Chapter
Supervisory Control and Data Acquisition System (SCADA): It is a part of the control system, but focused on the supervisory level. As such, it is a purely software package that is positioned on top of hardware to which it is interfaced, in general via programmable logic controllers (PLCs) or other commercial hardware modules (Daneels & Salter,1999)
Manufacturing Execution System: A collection of hardware/software components that enables the management to control production activities from order launch to finished goods. While maintaining current and accurate data, a MES guides, initiates, responds to and reports on plant activities as they occur. MES provides mission-critical information about production activities to decision support processes across the shop floor level of manufacturing management (Barkmeyer, Denno, Feng, Jones, & Wallace, 1999)
Enterprise Resources Planning: Configurable enterprise software that integrates business process across functions (Hwang, 2005)
Programmable Logic Controller (PLC): A small industrial computer used in factories originally designed to replace relay logic of a process control system and has evolved into a controller having the functionality of a process controller (Falco et al., 2004)
Scalability: Understood as the ability to incorporate into the existing system additional resources or meet diverse quality requirements.
Manufacturing Resources Planning II: Extends MRP by addressing all resources, in addition to inventory. MRPII links material requirements planning with capacity requirements planning, avoiding over- and under-shop loading typical with MRP (Bradley, 2005)
Distributed Control System (DCS): A supervisory control system typically controls and monitors set points to subcontrollers distributed geographically throughout a factory (Falco, Stouffer, Wavering, & Proctor, 2004)