In brief
Under DIN 31051, maintenance covers all measures that retain or restore the functional condition of a plant or piece of equipment.
Contents
What is Maintenance?
DIN 31051 divides maintenance into four basic measures. Servicing slows down the depletion of the wear reserve, for example through lubricating, cleaning or adjusting. Inspection determines and assesses the actual condition. Repair returns a unit to a functional condition after a fault or damage. Improvement increases reliability or maintainability without changing the required function. In addition, DIN EN 13306 defines maintenance terminology at European level.
Depending on when intervention takes place, a distinction is made between reactive (breakdown) maintenance, preventive (time- or usage-based) maintenance, condition-based maintenance and predictive maintenance. Which strategy fits depends on the consequences of failure, costs and plannability. Critical units are usually monitored on a condition basis, while non-critical components are often run to failure.
Every strategy requires the necessary spare parts to be available in time. Maintenance and spare parts management are therefore closely intertwined: maintenance schedules determine the plannable demand, failure risks determine the safety stock.
In practice: maintenance and procurement
For planned shutdowns, parts lists should go to procurement early so that long lead times do not jeopardise the schedule. For breakdown repairs, fast and unambiguous identification of the defective part determines how long the downtime lasts.
Synonyms and abbreviations: plant maintenance · equipment maintenance · maintenance and repair
Frequently asked questions
What is the difference between servicing, inspection and repair?
Servicing covers preventive tasks such as lubricating, cleaning or adjusting that slow down wear. Inspection determines and assesses the current condition, for example by visual check or measurement. Repair means restoring function after a fault or damage, usually by replacing or reconditioning parts. Together with improvement, these measures form the basic building blocks of maintenance.
Which maintenance strategy is the right one?
There is no universally best strategy. The choice depends on the consequences of a failure, the predictability of wear and the effort required for monitoring. For non-critical, easily replaceable parts, running to failure can be economical. Bottleneck equipment, by contrast, tends to be managed with condition-based or predictive maintenance. In practice, companies combine several strategies, tailored to the individual units.
Which KPIs are used in maintenance?
Common ones are mean time between failures (MTBF), mean time to repair (MTTR), technical availability and overall equipment effectiveness (OEE). In addition, maintenance costs relative to asset value, the share of planned versus unplanned work orders and spare parts availability are monitored. The figures only become meaningful when breakdowns and interventions are recorded consistently and uniformly.