process model

A process model is a structured, often graphical or data-based representation of how a process operates. It describes the sequence of activities, inputs and outputs, decision points, roles, resources, and rules that together make up a process. In industrial and regulated manufacturing environments, process models are commonly used to design, document, automate, analyze, and control production and quality workflows.

Key characteristics

Typical elements included in a process model are:

• Activities or steps: The tasks or operations performed, such as charging materials, mixing, heating, sampling, or inspection.
• Flow or sequence: The order and branching logic (for example, parallel steps, conditional paths) that connect activities.
• Inputs and outputs: Materials, data, or information consumed and produced by each step.
• Roles and resources: People, equipment, systems, or units responsible for or required by each activity.
• Business and control rules: Constraints, interlocks, calculations, recipes, and decision criteria that govern how the process behaves.
• States and transitions: Defined process states (for example, idle, running, held) and the events that move the process between them.

A process model may be expressed using diagrams (such as flowcharts, BPMN, or ISA-88 models), configuration objects in control systems, or data definitions inside MES, LIMS, or ERP platforms.

Use in manufacturing and regulated environments

In manufacturing, process models commonly appear in:

• Batch control and ISA-88: Models of procedures, unit procedures, and operations that define how a batch is executed and coordinated with equipment and recipes.
• MES workflow design: Electronic routings, operation steps, hold points, and data collection plans that represent the production process at the execution level.
• Quality and compliance processes: Models of deviation handling, change control, release workflows, and electronic approvals.
• Enterprise and supply chain processes: Representations of order management, planning, material flow, and logistics in ERP or planning systems.

A process model is descriptive by nature. It can be used as a basis for system configuration, software automation, training materials, or validation documentation, but it is not in itself an executed process or a proof of how the process actually runs.

Relationship to ISA-88

Within the ISA-88 context, a process model usually refers to standardized models that describe how batch processes, equipment, and procedures are organized. Examples include models of the process hierarchy, the physical model of equipment, and the procedural model of how batches are run. These ISA-88 models provide a consistent way to define and communicate batch processes across DCS, MES, and ERP systems, but they do not enforce a specific implementation or guarantee compliance.

Common confusion

• Process model vs. process map: A process map is often a simpler, high-level visualization of steps and handoffs. A process model typically has more formal structure, logic, and data definition suitable for automation or analysis.
• Process model vs. control algorithm: A process model describes the process and its workflow. A control algorithm (for example, a PID loop or advanced control strategy) describes how a control system manipulates variables within that process.
• Process model vs. recipe: In batch environments, a recipe defines specific parameters, setpoints, and materials for a given product. The process model defines the generic structure of operations and procedures that recipes use.