Entity model

An entity model is a structured representation of the key business objects in a domain, the data each object holds, and how those objects relate to one another. In manufacturing and industrial software, it commonly describes items such as materials, equipment, work orders, operations, batches, personnel, suppliers, and quality records.

The purpose of an entity model is to define what the system treats as distinct entities and how information is organized around them. It is used in databases, application design, integrations, analytics, and reporting. A well-defined entity model helps different systems refer to the same real-world objects in a consistent way.

An entity model usually includes:

• Entities: the core objects being tracked, such as a part, machine, lot, or production order

• Attributes: the properties of each entity, such as part number, revision, status, timestamp, or serial number

• Relationships: how entities connect, such as a work order consuming materials, or a batch being produced on a specific line

How it appears in operations systems

In MES, ERP, PLM, QMS, and related platforms, the entity model shapes how data is stored and exchanged. For example, if a system defines product, routing, operation, and inspection result as separate entities, integrations and reports can link those records more clearly. This matters for traceability, genealogy, scheduling, deviation handling, and audit evidence assembly.

Entity models are also important in system integration. When two systems use different entity models, mapping is needed so that one system’s object structure can be interpreted correctly by the other. For example, one platform may treat a batch as the main production entity, while another centers on serial numbers or work orders.

What it includes and excludes

An entity model includes the logical structure of business data and relationships. It does not by itself define screen layouts, process steps, user permissions, or physical database performance tuning, although those may be built on top of it.

It also does not necessarily specify every rule for how data changes over time. Those rules may be handled separately in workflows, state models, business rules, or application logic.

Common confusion

Entity model vs. data model: An entity model is often a type of conceptual or logical data model focused on business objects and their relationships. In practice, some teams use the terms interchangeably, but a full data model may go further into technical structures such as keys, data types, and normalization.

Entity model vs. object model: In software engineering, an object model may include behavior and methods as well as structure. An entity model usually focuses on the data entities themselves.

Entity model vs. process model: A process model describes workflow, sequence, or activity flow. An entity model describes the things the process acts on.

Manufacturing example

A simple manufacturing entity model might define material, lot, work order, operation, equipment, operator, nonconformance, and inspection record as separate entities, with relationships showing which lot was used on which work order, on what equipment, and with which resulting quality records.