introduce
All manufacturing processes, scenarios, operating modes, and technology applications described in this paper are currently used in a mature discrete and hybrid discrete/batch manufacturing enterprise that produces and repairs complex machines. The business manufactures products ranging from simple parts machined from bar stock to complex mechanical assemblies; the final product includes many in-house and third-party supplied sub-assemblies. Occasionally, the optimized operational definition differs for characterized and uncharacterized unusual operating modes or conditions. Optimal and abnormal operating modes are modeled using MES/MOM concepts as specified in ISA-95 Part 3, Manufacturing Operations Management Activity Model (MOM).
This paper explains a requirements definition approach using ISA-95 Part 3 modeling techniques to describe the integration of a manufacturing execution system (MES) with an enterprise manufacturing architecture as part of a MOM. By definition, MES functionality is part of the MOM system architecture that complements enterprise resource planning (ERP) and supply chain management (SCM) systems by providing essential information for production and support operations. This is a fundamental user requirement for transforming company operations to reduce reliance on manual data entry and improve data integrity from the manufacturing floor into the extended enterprise.
The implementation of MES/MOM introduces actionable real-time information to the paper-based workshop environment and culture, laying the foundation for the transition to a paperless workshop. This enables critical information to flow throughout the organization, including the sometimes overlooked production floor. Data collection from and to the shop floor must be transacted in real time with other enterprise systems to replace redundant, error-prone manual data entry methods. To optimize operations, information at the time of an event enables production control and line/unit supervisors to quickly identify bottlenecks and precursors to unusual events, and then schedule the necessary resources and work processes to prevent larger problems.
- MES/MOM integrates disparate shop floor applications deployed within manufacturing to unify the functionality of these legacy systems.
- MES/MOM avoids and eliminates siled knowledge bases by electronically mapping data content onto the MES, integrating and leveraging the intellectual property of current shop floor systems. This creates a clear form of manufacturing intelligence.
- MES/MOM accomplishes its enterprise mission through functional integration with other enterprise systems, providing bi-directional synchronization of manufacturing master data and workflow, and real-time exchange of operational data.
When integrating MES/MOM into other enterprise and equipment applications, a cohesive strategy of MES and MOM, utilizing manufacturing systems and integrating standards, can reduce operational and system lifecycle costs. MES integration of enterprise systems should leverage current best practices such as XML, web service technologies, manufacturing service bus (MSB) and enterprise service bus (ESB). These best practices have been proven to reduce integration costs to less than half of today's typical point-to-point costs, while delivering solutions in a fraction of the time.
Ultimately, an enterprise's MES/MOM implementation helps maintain operational visibility to ensure production and shipments are on schedule and operating costs are predictable.
This article has two parts:
The first section is background information, describing (1) the domain of discrete-hybrid manufacturing operations, and the three main operational applications and their touchpoints that support most company operations, and (2) the use of model-driven models based on the ANSI/ISA-95 series of standards method, system design and execution required to achieve MES/MOM.
The second part is a discussion of the advantages of applying the operating model approach to manufacturing operations. This section describes the advantages of operating with a comprehensive electronic record system rather than a paper-based system. These advantages are further demonstrated with the example of an "as-is" environment consisting of systems operating as silos and communicating information through paper-based records. A "pending" example then shows how the number of systems can be reduced to three classes of operating software with coordinated electronic interfaces. Finally, the paper concludes with the importance of using standards-based models to design the exchange of information between these systems.
Manufacturing Operations
End users, suppliers, and standards bodies have been working for 20 years to bring commercial enterprise and manufacturing systems to an out-of-the-box form that allows application configuration according to standardized workflows. As of 2012, the industrial software market has introduced tools based on the international MOM standard to minimize legacy, custom-built and siled systems at significantly lower cost than three to five years ago.
The framework of this MOM architecture takes the standardization of upper-level business processes and factory-level operation processes as the goal, and continuously improves and streamlines the mutual communication of these processes. In contrast to an enterprise's business processes, operational processes are not all required to function in the same way; in fact, the diversity of manufacturing operations, products, equipment, labor, and local regulations is such that standardization occurs only among departments and plants with similar types or forms of manufacturing processes. End-user organizations must recognize the needs of these different manufacturing types or forms, while learning mature processes and policies. When first attempting an MES/MOM project, many companies fail to recognize the need to standardize at the manufacturing form level by implementing streamlined operating processes across multiple plants. This trivial approach often results in project failure and substantial loss of capacity and capability.
Across the enterprise, applying standardized business and operational (by production form) processes creates consistency in:
- The type of data transferred between enterprise systems and various manufacturing sites.
- A concise set of small methods for communicating data across manufacturing operations.
- Quality data analysis is performed regardless of the factory where the product is produced or serviced.
Discrete and discrete mixed batch manufacturing processes
Discrete and discrete/batch hybrid manufacturing operations typically include operational activities in production, quality, inventory, maintenance, and overhaul and repair, resulting in a very diverse range of manufacturing operations and processes that need to be coordinated and managed.
An example of discrete and discrete/volume manufacturing operations are component manufacturing plants, which transform raw materials into semi-finished and final products through a series of manufacturing steps. Internally, parts factories supply original equipment manufacturer (OEM) factories that produce final assemblies and major components. Parts manufacturing plants start with raw materials, perform batch operations such as casting, electroplating, and forging, and perform discrete precision machining, welding, finishing, painting, packaging, etc.
Manufacturing businesses also include maintenance, repair and overhaul (MRO) operations and activities that take place at various industrial sites where previously manufactured items that have been put into service are completely disassembled, refurbished and rebuilt with a combination of original, refurbished and new components Assemble.
The MRO business recycles (overhaul and return service) many components and spares as refurbished spares into inventory in original quality specifications for future repairs for customers. Many companies can recycle hard-to-find parts for repairs and maintenance when they were first produced. An MRO business may be equivalent to a commercial-scale machine shop.
Determining the characteristics of the manufacturing process
Execution of the work process refers to the actual production of quality goods or the repair and maintenance of equipment. Physical activity occurs on the shop floor, where manufacturing technicians receive and consume materials to produce final items. The nature of these activities is complex and varied.
The manufacturing work process described in Figure 3-1 consumes raw materials that are combined with subassemblies and parts to produce new end products. This process uses a bill of materials (BOM) during production. Processes performed at these plants include Build-to-Order (MTO) and Engineer-to-Order (ETO).
Figure 3-1: Production workflow
As shown in Figure 3-2, maintenance, repair, and overhaul processes within an enterprise are usually more complex. The final item is both the object of a production or work order and a material component on the bill of materials. This process requires serialization tracking, where subcomponents often return to the original component.
Figure 3-2: Maintenance workflow
Enterprise domain (architecture)
To achieve its goals, a manufacturing enterprise relies on various internal organizations whose missions are far-reaching. As shown in Figure 3-3, these organizations include engineering, planning and scheduling, and manufacturing operations. They provide information bi-directionally to create, maintain or repair products across the industrial base. Each has a specific role and is responsible for functions, tasks, and data exchange, but none of these organizations can work effectively without timely data from other organizations. In small companies, engineering/planning and scheduling/manufacturing are usually in the same building, or at least in the same location, making communication between them easy to facilitate; however, as the business scales, (perhaps) across multiple time zones With multiple locations, the amount of time-critical information that needs to be managed increases, and the ability to effectively distribute and maintain information becomes increasingly difficult.
Figure 3-3: Organizational activities
To control the flow of information in manufacturing, Engineering/Planning & Scheduling/Operations groups work with various suppliers and service providers to deploy specialized applications for their specific roles (functions, tasks, and timed communications) within the enterprise. Most of these applications were originally developed to help standardize data and communication methods within a specific group or organization. As these applications evolved, standardized communication protocols and methods were adopted to coordinate the timing of data transfers between different business groups, thereby greatly improving the efficiency of the process.
Among the many enterprise-level applications, this article focuses on three groups of functions that have a direct impact on shop floor operations. The following sections contain general descriptions of these application categories.
Enterprise Resource Planning
An ERP system integrates enterprise-level business information, namely finance, accounting, human resources, supply chain management, and customer information. The goal of ERP software is to mirror the business processes of an enterprise and help manage key parts of the business on an enterprise level. This includes supply chain activities and processes defined by the Gartner group as ERP II.
Shop floor activities are supported by an ERP system and typically include:
- order tracking
- Maintain inventory
- product planning
- supplier interaction
- Parts procurement
- customer relations
Product Lifecycle Management (PLM)
Resource planning, supply chain, and manufacturing operations activities within Tier 3 of the MOM domain all rely on current product configuration information maintained by engineering centers. In large enterprises, many organizations primarily use PLM as an application to manage the entire product lifecycle.
The content of PLM data includes engineering bill of materials (eBOM) and technical data, as well as high-level operational workflow models of final assembly OEM factories. From a shop floor perspective, PLM is an engineering system that maintains OEM data, drawings, models, technical data, etc. PLM systems provide many other functions, but for the purposes of this article, it is their ability to manage engineering data that is of interest to us.
MES is a shop floor execution system for production operations, used in a real-time workflow MOM architecture to synchronize production, supporting MOM activities for maintenance, quality and inventory operations. The MES function of the MOM layer guides operators to interact in the workflow execution route of producing or maintaining products. The MES/MOM function, as explained in the third layer of the MOM domain model of the ISA-95 standard Part 1, is implemented as follows:
- Workflows in the Execution Path
- Specific work instructions for each step in the ticket route
- collected data points
- quality inspection
- Sign-offs to verify the completion of work steps and operations within a route.
MES/MOM provides workflow, event and order visibility, and event notifications to ensure manufacturing information meets business needs. At the same time, the verification of workflow by MES reduces non-value-added activities, improves data accuracy, and provides ERP systems with the required real-time data to maximize the effectiveness of enterprise processing, planning, and scheduling.
MES applications act as messengers, intermediaries and coordinators between the shop floor, enterprise engineering (PLM) and enterprise planner and scheduler (ERP). When an operator initiates a data request from ERP or PLM, the MES application connects to the corresponding system and retrieves and displays specific information for each production order, operation and operation step in a user-defined interface for execution, verification and coordination Event-driven workflow. In an ideal world, the fact that there are at least three different enterprise-level systems co-existing would be transparent to people on the shop floor. MES functions, tasks and exchanges directly support and execute real-time workflows to complete production orders.
Integrated Enterprise Systems
Armed with this basic understanding of the manufacturing enterprise and manufacturing operations systems depicted in Figure 3-4, the next step is to determine the level of integration required with each system. Let's briefly review:
- ERP plans, schedules and releases work to the shop floor.
- PLM provides product standards and engineering data for developing operational workflows.
- MES/MOM defines the real-time workflow on the shop floor required to perform and validate the work.
Figure 3-4: Manufacturing System
Every business uses some form of these three systems, depending on product line, order mix, manufacturing type/form, and degree of product standardization (from standardized "make-to-stock" (MTS) to customized "engineer-to-order" products ), with different functional emphases. The goal of each business is to identify its optimized operational workflows, the correct operating model, and the manufacturing systems needed to support those optimized workflows.
There are now some ERP software suites on the market that can perform limited PLM and MES/MOM functions for production-to-stock, low SKU, and low-complexity manufacturing workflows. PLM software can also be used for limited ERP and MES/MOM functions, and MES/MOM software can be used to perform limited ERP and PLM functions. However, no single software package has been developed that can successfully perform the tasks of all three functional sets in all forms of discrete hybrid manufacturing and supply chain scenarios. The functional and IT architectural requirements are significantly different for planning, design, product support and execution of real-time workflows. To avoid high customization and life cycle costs, a business with different product and manufacturing types must leverage the respective strengths of three separate systems rather than trying to have one or two systems override the functionality of a third.