An MES consists of the computer systems used to manage production and daily operations of a production facility. The MES lies above the actual shop floor in the enterprise system hierarchy and is not in direct contact with the actual production.
However, the systems guide, initiate, respond to and report on the production activities as well as distribute information to the company´s other IT systems, bridging the gap between the control systems of the shop floor and the information systems on an enterprise level.
The advantages that have been experienced by companies implementing MES are reduced cycle time, improved product quality and reduced cost.
Implementing smart manufacturing methods will increase the complexity of the activities performed and communications regarding both the product and the assets of the factory itself (e.g. machines, sensors,systems).
Challenges faced by an MES mainly result from the variance in the level of information detail and data processing required between enterprise functionalities . As a result, the role of the MES is defined by several industry standards that identify what functionalities and data flow an MES should include, and how it should be integrated with other information systems, such as enterprise resource planning (ERP).
For the companies evaluating MES vendors, it is critical that their needs and requirements of the system are clearly defined. The lack of clear requirements is a common reason for canceled software implementation projects. However, it is unclear for most manufacturers what information is needed by the vendors to enable this evaluation. There exists a need for a methodology to identify business-specific functional needs and requirements of an MES implementation including a standardized way of expressing those requirements, that align with the industry standards and the desires from MES vendors or developers.
The purpose of this Blog is to generate a general approach to making an initial assessment of an enterprise’s MES needs and requirements. The approach, with a basis in the MES industry standards and software implementation standards, will provide a methodology to efficiently define company needs in terms of the scope of an MES system.
The scope will be analyzed based on business needs and business problem areas to define the prioritized functionalities of the MES. The methodology will provide an approach to proceed with the assessment of a specific implementation project covering these prioritized functionalities. This will provide the information needed to in a final step generate a specification of the specific requirements of the implementation.
The Blog will focus on the initial assessment of an MES implementation. The information will adopt exclusively the MES standards of MESA (manufacturing execution system association) and ISA (industry, system and automation society), other existing standards will not be considered when developing the methodology.
The industry standards defining an MES were estimated and the IS-95 (ANSI/ISA-95 Enterprise control system integration) and MESA 11 standard were defined as the most established and accepted standards.
These standards are in this blog examined in detail to gain in-depth knowledge of the common understanding of what an MES is and how it should function.
MES is a class of information systems built to support shop floor processes and their integration to the enterprise IT-system architecture. The main goal of an MES is to improve and optimize the production management function and increase visibility into the manufacturing process.
When describing a manufacturer’s IT-architecture the enterprise is often divided into three layers, where MES is the middle layer between enterprise IT-systems and shop floor control systems, The top-level often referred to as company management level includes central functions such as finance, human resources sales, and purchasing. These functions are often supported by an EPR (enterprise resource planning) system.
The bottom layer is often referred to control or automation level and includes all functionalities related to direct production control and is often supported by PLCs (programmable logic control), SCADA (supervisory control and data acquisition) or other control systems.
The mid-layer, often referred to as the manufacturing operations management layer is supported by MES, and the systems gather, process and distribute data from both the software and hardware at the control level and the ERP on the company management level.
The role of an MES can vary depending on the manufacturing company as a result of the business model, manufacturing system setup or production model.
Though, the high-level functionalities of an MES often include production order scheduling, execution and monitoring, inventory and material management, tool and machine management, data acquisition, analytics and reporting, and quality management, tracing, and genealogy.
Today an MES often consists of multiple systems that are patched together, leading to complex and costly integrations for any new functionalities or software.
MESA (Manufacturing execution system association)
It is an American industry association, that was established in 1992 by different software companies. Before MESA was founded, every software supplier had its own definition of MES. MESA gathered the major actors on the market and proposed a standardized definition of MES that today has worldwide acceptance.
“MES delivers information that enables the optimization of production activities from order to launch to finished goods. Using current and accurate data MES guides, initiates, responds to and reports on plant activities as they occur.
The resulting rapid response to changing conditions, coupled with a focus on reducing non-value-added activities, drives effective plant operations and processes. The MES improves the return on operational assets as well as on-time delivery, inventory turns, gross margin, and cash-flow performance. An MES provides mission-critical information about production activities across the enterprise and supply chain via bidirectional communications.”
The MESA-11 standard is function-focused and identifies 11 principal MES functionalities to meet the needs of various manufacturing environments, which are additional described in the following paragraphs. These roles are according to MESA required for effective support of production management.
1. Product tracking and genealogy: Monitoring the progress of units, batches, and lots of output.
2. Resource allocation and status: Guiding the resources, people, machines, tools, material, and documents required to perform a task. Answering questions such as: What should they do, what are they currently doing or have just done?
3. Performance analysis: Comparing the measured results with the goals and metrics set up by the corporation, customers, or regulatory compliance.
4. Process management: Directing the flow of work in the plant-based on planned and actual production activities.
5. Data collection acquisition: Gathering, monitoring, and organizing data about the processes, materials, and operations from people machines or controls.
6. Quality management: Recording, tracking, and analyzing product and process characteristics against engineering ideal.
7. Labor management: Tracking and directing the use of personnel during a shift based on qualifications, work patterns, and business needs.
8. Dispatching production units: Giving the command to send materials or orders to certain parts of the plant to begin a process or step.
9. Detailed Scheduling: Sequencing and timing activities for optimized plant performance based on finite capacities of the resources.
10. Maintenance management: Managing maintenance activities and information.
11. Document control: Managing production documentation and revision control.
ISA-95 (Instrumentation, system, and automation)
It presented ANSI/ISA-95 Enterprise control system integration (internationally known as IEC/ISO 62264 and commonly referred to as ISA-95).
The main objective of the ISA -95 is to define and standardize the interfaces of enterprise activities and control activities. The ISA-95 standard identifies sub-systems of an MES and defines the boundaries between the ERP, MES and other automation systems. Additionally, a clear delimitation of responsibilities and functionalities for separate business departments is presented. ISA-95 also provides a standardized terminology and consists of a set of concepts and models for integrations of production control systems with enterprise systems to improve communications.
ISA-95 consists of 5 parts that cover different standards related to the manufacturing control systems landscape.
1. Standard provides models that are defining the system related enterprise hierarchy as well as the interface between the top levels of the hierarchy model, which are the manufacturing control functions and enterprise functions. Also defining the scope of manufacturing operations and control functions.
2. Standardize the interface and structure of the information flow between the enterprise and control systems by deep diving into standard attributes of the objects
3. Focuses on models defining the activities and data flows of manufacturing operations that enable integration with the enterprise systems.
4. Specifies the data flow between the activity groups
5. The standardized format of data messages transacting between the enterprise and the control systems.
The aim of building a standardized framework and methodology for making an initial assessment and defining business needs and requirements of a manufacturing operations control system, some parts of the ISA-95 standard are redundant and contain unnecessary details.
Terminology & Models
The first part of the ISA 95 standard defines the standard terminology and object models used throughout the standard. We can divide into 3 types of models.
- Hierarchy models
- Data flow models
- Object models.
These models define the interface between a business system and control systems of an enterprise. It clarified what activities should be owned by which system and how they should be integrated.
Scheduling and control hierarchy
the ISA-95 defines the levels from the shop floor to top management, where the time frame in the top-level focuses on the span of years, months, and weeks. From level 3 and below the time span of information flow varies between hours to seconds or milliseconds for the actual production control.
The ISA-95 standard mainly covers the activities of level 3 and level 4 and the interface between these. the main activities of the 3rd level of the model, which are closely related to the 11 activities defined in the MESA standard. These activities and their functionalities are described in more detail in the following sections.
1. Resource allocation and control
- All resources directly related to control and manufacturing needed for the work to be started and through completion, such as machines, personnel, tools, documents, etc. Additionally, the control domain is also responsible for making sure the equipment is set-up for production as well as providing real-time status and past use of resources.
2. Dispatching production
- Dispatching production to specific personnel or equipment lies within the control domain and includes dispatching information such as jobs, orders, batches, etc. With this functionality, the WIP (work in progress) can be controlled by managing buffers and rework processes.
3. Data collection and acquisition
- Within the control domain, the functionality of obtaining information from the production floor Is crucial. This functionality includes both operational data as well as data associated with a certain process or machine.
4. Quality management
- The control domain is accountable for providing quality-related data collected from manufacturing, such as test results, to enable product quality assurance. Also, the data collected from manufacturing can be used for analysis to identify issues, recommend actions, correlating symptoms to determine a problem cause, etc.
5. Process management
- The functionality of monitoring production processes and provide operator support for corrections or in process improvements lies within the control domain. It may include alarm functions for ensuring awareness of process deviations that are outside the acceptable tolerance.
6. Production planning and tracking
- The functionality of production planning and tracking, which includes keeping and providing production status. This may include for example resource allocation for a specific order, current production conditions, and production exceptions such as rework.
7. Performance analysis
- The data collected within the control domain enable the functionality of real-time reporting on manufacturing operations. The reports can contain PKI results, such as utilization, cycle time, WIP levels, OEE (overall equipment efficiency), etc.
8. Operations & detailed scheduling
- To minimize production set-up time the control domain contains the functionality of sequencing orders in the production schedule based on for example priority or product type.
9. Document control
- Here we can controlling and maintaining records related to a specific production unit. The records may include drawings, SOPs (standard operating procedures), recipes, etc. The document control activities also include distributing the records, by for example providing an operator with the correct instructions.
10 . Labor management
- Within the control domain some of the labor-related functionalities lies, such as time reporting and training and certification tracking. This functionality often collaborates with the resource allocation function to optimize the allocation of personnel based on for example competence.
11. Maintenance Management
- To ensuring equipment availability is included. This is based on the scheduling of periodic and preventive maintenance work, which may lie within the control domain. In the control domain, a history log is stored in the maintenance activities performed in the production.