work order

Core meaning

A **work order** is a formal, uniquely identified record that instructs authorized personnel to perform a defined piece of work. It typically specifies:

– What work is to be done (task description or job plan)
– Where it is done (asset, location, line, area, or product)
– When it should be done (schedule, priority, due date)
– Who is responsible (person, role, or department)
– Required materials, tools, and documentation

Work orders exist in many enterprise systems (ERP, CMMS, EAM, MES) and are used to control, document, and trace work performed on equipment, facilities, products, or processes.

Usage in industrial and regulated environments

In industrial operations, work orders commonly refer to two main categories:

1. **Maintenance work orders**
– Raised in CMMS or EAM systems for preventive, corrective, or predictive maintenance.
– Linked to specific assets (machines, instruments, utilities) and maintenance plans.
– Capture execution data such as labor hours, parts consumed, failure codes, and completion dates.

2. **Production work orders** (sometimes called manufacturing orders or process orders)
– Created in ERP or MES to authorize production of a specific quantity of a material or product.
– Define routing, operations, materials, and sometimes quality checks.
– Used to record production quantities, scrap, and relevant traceability data.

In regulated environments, work orders are often treated as controlled records. They may reference validated procedures, SOPs, or standard job plans, and are typically subject to change control when their structure or content is modified.

Structure and data elements

While formats vary by system, a work order record commonly includes:

– Unique work order number or ID
– Work type (e.g., preventive maintenance, corrective maintenance, production, calibration, facility work)
– Asset, equipment, line, or product identifier
– Detailed task description or reference to a standard plan/recipe
– Priority, requested start/finish, or schedule
– Requestor and responsible owner
– Required materials, tools, permits, or documents
– Status (e.g., requested, approved, scheduled, in progress, completed, closed)
– Execution and closure data (actual start/finish, labor, parts, comments, measurements)

Site-context: MES and maintenance integration

When discussing MES integration with maintenance systems (CMMS/EAM), the term “work order” most often refers to **maintenance work orders**:

– MES or OT systems may **trigger maintenance work orders** based on conditions such as equipment alarms, downtime events, or quality-related holds.
– CMMS/EAM systems manage the **full lifecycle** of the maintenance work order, while MES may only send triggers or display status.
– Integration is usually designed so MES can **see or influence** work order status for equipment, without replacing the maintenance system as the system of record.

In the same environment, MES and ERP may also exchange **production work orders**:

– ERP creates production work orders and sends them to MES for detailed scheduling and execution.
– MES uses work order information to associate production data, quality results, and genealogy with specific orders.

Boundaries and exclusions

A work order, in this context, **is**:

– A controlled record used to authorize and document work on assets, facilities, or products.
– Part of formal workflows in systems like ERP, MES, CMMS, or EAM.
– Often a key object in traceability, reliability, and compliance reporting.

A work order, in this context, **is not**:

– An informal request (e.g., an email or verbal instruction) without a unique ID and tracked lifecycle.
– A spare parts order or procurement order, although work orders may reference such documents.
– A full procedure or SOP; it usually references underlying procedures rather than replacing them.

Common confusion and terminology

The term “work order” can be confused with related concepts:

– **Maintenance request / service request**: an initial request for work, which may or may not be converted into a formal work order.
– **Production order / process order / manufacturing order**: in some ERP and MES systems, these are specialized types of work orders focused on production rather than maintenance.
– **Job ticket / job card**: often used informally or locally to describe the printed or shop-floor representation of a work order.

In many plants, “work order” is used generically for both maintenance and production, so systems and procedures usually clarify the work type or owning system (e.g., “maintenance WO in the CMMS” vs. “production WO from ERP”).