operation

In industrial and manufacturing contexts, an operation is a defined segment of work performed to achieve a specific outcome within a larger process or procedure. It typically groups related tasks or actions that transform materials, data, or equipment states in a controlled and repeatable way.

General meaning in manufacturing

On the shop floor, an operation commonly refers to a specific step in a routing, work order, or job sequence. Each operation usually has:

• A defined purpose (for example, machining, assembly, inspection, cleaning)
• Assigned resources (equipment, tools, materials, and personnel or role)
• Execution conditions and parameters (such as speeds, temperatures, or tolerances)
• Start/finish criteria and recorded results (quantities produced, scrap, measurements)

In IT/OT systems, operations are often represented as records or objects in MES, ERP, or scheduling systems, with identifiers (such as operation numbers) that link to work instructions, recipes, or control logic.

Operation in ISA-88 (S88) batch control

Within the ISA-88 batch control framework, an operation is a level in the procedural hierarchy used to describe how a batch is executed. The procedural model is commonly expressed as:

• Procedure
• Unit procedure
• Operation
• Phase

In this hierarchy, an operation is a logical grouping of phases that carry out a coherent portion of the unit procedure. For example, in a mixing unit procedure, operations might include “charge materials,” “mix,” and “discharge.” Each operation is more detailed than the unit procedure but less granular than the individual phases (such as open valve, start agitator, or start heating).

Operations in ISA-88 are typically modeled in the control system or batch management system and linked with MES recipe management and electronic records for traceability and validation.

What an operation is not

• It is not the entire process or batch on its own; it is one step or segment within a higher-level procedure or routing.
• It is not necessarily a single manual action; operations often contain multiple detailed actions or phases.
• It is not limited to physical equipment steps; data processing, quality checks, and documentation steps can also be modeled as operations in MES or workflows.

Operational use in systems and workflows

Across OT and IT systems, operations appear as:

• Routings and work orders: Each operation has planned duration, required resources, and completion tracking.
• MES execution steps: Operations may be the units for electronic work instructions, data collection, and electronic signatures.
• Control system logic: In batch systems following ISA-88, operations organize the phases executed by controllers and units.
• Reporting and KPIs: OEE, cycle time, and nonproductive time are frequently analyzed at the operation level.

Common confusion

• Operation vs. process: A process is the overall sequence that delivers a product or outcome; operations are the individual steps within that sequence.
• Operation vs. phase (ISA-88): A phase is the most granular, equipment-oriented step executed by the control system. An operation groups multiple phases into a meaningful functional segment of the unit procedure.
• Operation vs. activity or task: Activities or tasks are often used for more detailed, human-level actions inside an operation, especially in digital work instructions.

Relation to the ISA-88 procedure context

In the ISA-88 view of a procedure, the operation serves as an intermediate level of detail that connects high-level unit procedures to low-level phases. Modeling operations clearly helps align batch control logic with MES recipe structures, quality records, and validation documentation in regulated manufacturing environments.