Glossary · Safe work, maintenance and competence
Maintenance interval
Also known as: service interval
German: Instandhaltungsintervall
In maintenance, a maintenance interval is the specified time, usage or condition threshold between maintenance activities on a machine or component.
- Machine safety
- Maintenance
In one sentence
A maintenance interval sets when maintenance is due, by time, usage or condition, and for safety components it follows design assumptions.
Example
The contactors in the safety circuit of a press are to be replaced after 1 million switching cycles, the value used in the reliability calculation, while the hydraulic filter is changed at a pressure-drop threshold.
How it applies
- Machine safety: Reliability values such as MTTFd assume that wear parts are replaced in time. If the maintenance interval in the manual does not match the assumption, the calculated performance is not achieved.
- Technical documentation: Give each interval with its unit and trigger, and say which applies first when several are given. Separate safety-relevant intervals from general ones.
- Integrated systems: Condition-based triggers depend on sensors and data. Define what happens when the data is unavailable.
- Evidence: Maintenance records show the interval was kept. Field data on failures helps adjust it for preventive maintenance.
Maintenance interval vs. inspection interval
A maintenance interval schedules work that changes the condition of the machine. An inspection interval schedules checks of that condition.