In fact, this situation still exists today for many manufacturers. Professional organizations had no common method to teach batch methods to engineers and process managers. There was no commonality between vendor and user models, and manufacturing requirements were poorly communicated between users and suppliers.
This led to manufacturing systems that were (and many still are) difficult to build and configure, ultimately resulting in a high cost of system ownership and highly inefficient engineering to production workflows.
The main goal of the ISA88 standards, Parts 1 through 4, is to separate the product knowledge in recipes from equipment capabilities. This allows recipe development without process control equipment knowledge. The end result is flexible manufacturing based on utilizing the same equipment and process to produce multiple products.
More than batch
One stigma of ISA88 has been its name. ISA88 is not just about batch industries. It directly applies to sustaining flexible manufacturing practices in discrete, continuous and batch industries.
ISA88 defines a model for batch (work order, lot) control and provides a common terminology for industry. The standard defines a data structure that enables data integration both within the process and with enterprise applications including Structured Query Language (SQL) tables for recipes, equipment, schedules and history. Additionally, the World Batch Forum (www.wbf.org) is developing XML schema, called Batch Markup Language (BatchML), for data exchange.
After evaluating eight years of application of the ISA88 standard, the World Batch Forum reports many realized benefits to industry. These include a 20 percent reduction in the cost of automated systems, 30 percent reduction in time to implement and change systems, reduced time to develop product definitions from days to hours, reduced standard deviation of batch cycle times by 50 percent and reduced number of required operators by 33 percent.
The standard’s four parts are: Part 1, models and terminology; Part 2, data structures; Part 3, equipment independent recipes; and Part 4, production records.
Part 1 defines models and terminology with three co-dependent models for flexible manufacturing. The physical, or equipment, model discusses how to effectively organize an equipment hierarchy from a high level to a detailed plant level. The procedural and process model shows how to effectively organize process and production rules. Procedure and equipment are aligned to create a production process.
Part 2, Data Structures and Guidelines for Languages, brings detail to ISA88.01 by establishing the structure and language used to represent recipes.
The Data Model defines the main classes and the relations between these classes for the batch domain that is described by the Control Activity Model of Part 1.
Part 3 extends the Part 1 description and defines General and Site Recipes as special recipe types called “Equipment Independent Recipes” or EIR. The EIR data model identifies the objects and relationships of general and site recipes.
Draft Part 4 includes production records, production record specifications, business information, execution information and production record reports. Part 4 provides a standard format for maintaining and exchanging production records, which contain a selected subset of production data and batch history data.
Charlie Gifford, [email protected], is Business Development Director for Oakville, Ontario, Canada-based systems integrator, Aseco Integrated Systems, and a member of the SP88 and SP95 committees.
