Backlog

A backlog commonly refers to a prioritized list of work items that have been identified but not yet completed. In industrial operations and manufacturing, this usually represents work that is queued, waiting to be planned, scheduled, or executed.

In manufacturing and industrial operations

In regulated manufacturing environments, a backlog can include:

• Production backlog: Confirmed customer orders, work orders, or batches that have been released or approved but not yet processed through the shop floor.
• Maintenance backlog: Preventive or corrective maintenance tasks that have been logged in a CMMS or EAM system but are not yet completed.
• Quality backlog: Open nonconformances, CAPAs, inspection lots, or test activities awaiting review, disposition, or closure.
• IT/OT change backlog: Requested changes, enhancements, or fixes to MES, ERP, SCADA, or other systems, often managed in a ticketing or agile tool.

Backlogs are often maintained in digital systems such as ERP, MES, QMS, EAM/CMMS, or agile project tools. They are typically ordered by priority, due date, risk, or regulatory impact to support planning, resource allocation, and compliance oversight.

Operational meaning

Operationally, a backlog indicates work that is known, documented, and pending. It:

• Helps planners and supervisors see upcoming demand on equipment, labor, and materials.
• Supports compliance by showing traceable records of identified but incomplete tasks (for example, open audit findings or open NCRs).
• Is often reviewed in production meetings, tier meetings, and continuous improvement reviews to address bottlenecks and overdue items.

A backlog does not include work that is completely unknown or unrecorded, and it does not necessarily imply a problem by itself. Issues arise when backlogs grow faster than they can be worked, or when critical items remain unresolved beyond defined timeframes.

Common confusion

• Backlog vs. WIP (Work in Process): WIP refers to work currently being processed on the shop floor. Backlog usually refers to work waiting to start or waiting for a specific action (for example, review, approval, or scheduling).
• Backlog vs. capacity: Backlog is the queue of work. Capacity is the available ability to complete that work (people, machines, time). A large backlog is not the same as high capacity.
• Backlog vs. order book: An order book may show all confirmed orders. The backlog is typically the portion not yet completed or shipped.

Use in agile and IT/OT contexts

In agile or DevOps approaches applied to manufacturing IT and OT systems, a backlog is the ordered list of user stories, features, defects, and technical tasks for systems such as MES, ERP integrations, dashboards, or automation projects. Teams pull from this backlog into sprints or work cycles, using it as the single source of planned work.