Ask two managers in the same plant how a line performed last week and you can get two answers, because the production team reads one system and the maintenance team reads another. That is the problem a one source of truth for OEE and maintenance is meant to solve. The root cause is structural: a single machine stoppage is one physical event, but in most plants it generates two disconnected records, an availability loss in the OEE tool and, if someone remembers, a work order in the CMMS. Seiichi Nakajima's Total Productive Maintenance framework classifies downtime into six big losses, and none of them respect the boundary between your monitoring software and your maintenance software.
Picture a filler that stops at 14:07. The OEE system logs an availability loss and, at best, a stop reason an operator picks from a list. Separately, if the stop is serious enough, someone opens the CMMS and raises a work order. Now the same few seconds of reality exist as two records, entered by different people, at different times, in different vocabularies. They will never perfectly agree, and every report built on top of them inherits that disagreement. One source of truth means the stop, its cause, the work order, and the parts used are the same object, recorded once.
Concretely, a unified model ties together data that siloed tools keep apart.
Mean time to repair and mean time between failures are only as trustworthy as the log they are computed from. If downtime lives in the OEE tool and repairs live in the CMMS, then MTTR is assembled by joining two datasets that were never meant to line up, and the number quietly drifts from reality. When both sides of every event come from one database, MTTR and MTBF are byproducts of the record rather than a reconciliation project. It also changes how fast you can act on those metrics, because a rising MTTR trend points straight back to the linked stops that caused it, with no data-matching step in between. That is the difference between metrics you report and metrics you can defend in front of an auditor.
Nakajima's six big losses, breakdowns, setup and adjustment, idling and minor stops, reduced speed, defects and rework, and startup losses, span production and maintenance by their nature. A breakdown is a maintenance event and an availability loss at the same time. A minor stop is a performance loss that may still point to a maintenance cause. Analyzing these across two systems means constantly translating between them. Housing them in one data model lets you see, for a single asset, which of the six losses dominates and which maintenance action moves it.
One source of truth is not a nicer dashboard, it is a decision about where your data lives before any dashboard is drawn. When a stoppage writes one record instead of two, production and maintenance finally describe the same reality, reliability metrics stop drifting, and the six big losses become analyzable across the whole plant. That is why a single-database platform like Fabrico beats even two excellent tools bridged by a connector: the connector can synchronize records, but it cannot make them one.