09 April 2001
Modern batch systems accelerate with business
E-business pressures all forms of automated manufacturing to 'step it up.'
Talk integration to a vendor and a customer and you're likely to get two very different points of view on the topic, despite the emergence of standards designed to reconcile these differences.
By too carefully defining the limitations of software packages, one risks limiting the functionality of the very manufacturing operation one intended to improve.
A responsive, integrated batch solution must be capable of positioning itself in the context of the enterprise production system, responsible not only for executing a planned sequence of operations but also for the wider repercussions of its actions.
An application might easily require that the asynchronous manual and automatic activities of more than 100 recipes be tied to stock movements to ensure that raw material is available at the right place and time. Synchronization is integration, both at the batch and the enterprise levels.
The plant as link in the chain
The relationship between plant and enterprise has become critical in allowing companies to keep pace with the accelerating speed of business. Real-time plant systems and information play a key role in enabling the supply chain to be responsive to the market.
To compete effectively, companies must be faster and more flexible in responding to customer demands. They do this by reducing the size of the task ahead, which they do by identifying solutions that are as focused and all encompassing as possible.
Further, they reuse and protect their previous investments by encapsulating legacy systems, and they choose a component-based system that is the most flexible, is the fastest, and has the least costly architecture to own and maintain.
Success in the new e-business economy will depend on the synchronization and coordination of the plant as part of the supply chain.
Batch production plants strongly reflect these evolving market trends. The best batch operation strives to manage products of ever-smaller lots, reducing warehouse stock, checking quality online, respecting ever-closer delivery dates, and in general adjusting production to the evolution of issues and ideas.
The IPS approach
One approach, the Integrated Plant System (IPS), focuses on the make process of the Supply Chain Operations Reference (SCOR, www. supply-chain.org/) model and the synchronization and coordination of plant and supply chain.
The IPS includes a framework engine able to smoothly encapsulate and synchronize the various production processes while guaranteeing flexibility to the system.
The module provides an object-oriented graphic environment, which guides users when carrying out projects via three different phases:
- Analysis: defining the plant's physical structure, flows of internal data and materials, and the rules governing them.
- Development: the phase when one adds standard library modules, encapsulates legacy modules, and creates new software modules that incorporate rules from the analysis phase.
- Administration: the phase in which it is possible to monitor the execution of rules and quickly change the flow of parameters in order to keep the system up to date on changes in the plant or its products.
Define the data
Although this phase often is not the most costly, it is during this phase that decisions are made having the greatest bearing on the final cost of an entire automation project. Hence a tool allowing for the proper management of this phase is most important.
Object-oriented analysis is a key to this step. Operators and managers unconsciously fashion objects such as the following:
- Plant objects: mixers, conveyor belts, weighing systems, and others
- Logical objects: objects that contain data such as work orders, reports, quality certifications, and the like
- Connections between objects: flows of data and materials
- Rules for defining standard operating procedures for plant management
These insert into the manufacturing execution system (MES), which also serves to establish a correct interpretation of the specifications and terminology employed in the application.
This is the phase for defining the plant through its successive steps. This permits area objects to contain unit objects, which in turn contain equipment objects, and so forth, in a process of validating and fine-tuning the model.
In the same way, objects pointing to various databases present in the plant represent the data model. These would include real-time, analysis, work order, and batch report databases, as well as others.
So, using IPS, technology experts can navigate inside each of the model's individual objects. ANSI/ISA-88.01-1995, Batch Control Part I: Models and Terminology, is the basis for the model. Managers use the model and gain vision into the functions and data exchanges in the plant.
In a similar hierarchical manner, rules exist for managing the functioning of the plant's various areas. To store, structure, and archive all production data is an important activity of any MES, yet this is usually not enough.
IPS helps plant managers define rules for managing such data to increase plant performance. The ability to make modifications and the simplicity in managing the software, by encapsulating the plant's principal functions in graphical objects, permits users to export strategies implemented in diverse plants within the same company on different sites.
Work outside the system
In the development phase, the key is opening up communication outside the system. The integration of the MES with any existing distributed control system, programmable logic controller, single loop, or other intelligent management system is a basic requirement.
Furthermore, it is necessary to integrate business systems at higher levels such as warehouse management, work orders, bills, and the like, as well as those existing at the intermediate level such as laboratory management and schedules. Complying with de facto standards such as OLE for process control, component object model, distributed component object model, Java, and others facilitates this communication.
During the administration phase, the key is flexibility. Oftentimes plant managers must make sudden online changes to IPS logical rules for coordinating subsystems. IPS makes this a simple and fast procedure.
It is important to point out that an MES designed for batch plants must be kept up to date in order to fulfill the basic demand of providing a decision-making support tool. Performing appropriate data searches and presenting the appropriate information on the right PC to the right person at the right time is essential. IT
Figures and Graphics
Alastair Orchard has a degree in chemical engineering. He's worked for the Texaco and BP oil companies. He now works for Orsi's consultancy group as an application technology manager.