Machine maintenance is a phrase that covers everything from wiping a chain to a full overhaul, and the useful way to think about it is by task type, because the four types behave differently and get scheduled differently. There is cleaning and inspection, which is cheap and frequent. There is lubrication, which is cheap, frequent and the commonest thing to skip. There is adjustment and calibration, which is periodic. And there is replacement of wearing parts, which is expensive and should be predicted rather than discovered. This page sets the four out and explains how to set intervals for each.
Cleaning and inspection is where findings come from
The cheapest task and the one that generates most of the knowledge. A technician who cleans a machine sees what is wearing, and a machine that is never cleaned hides its own condition. This is the task most easily cut when a schedule is over-committed, and cutting it removes the evidence you would use to justify everything else.
Lubrication is cheap, frequent and quietly skipped
It has the highest ratio of consequence to effort of anything in maintenance, and it is the task most often marked complete without being done, because nobody can tell afterwards. If your findings never mention lubrication, that is worth investigating rather than celebrating.
Adjustment and calibration follow the process, not the calendar
Tension, alignment, settings drift with running rather than with time. These belong on usage intervals where you can collect readings, and on conservative calendar intervals where you cannot, with a note that the interval is a proxy.
Wearing parts should be planned replacements
The whole argument for preventive maintenance sits here: a belt changed at a chosen moment costs 1.1 hours on the worked example this site publishes, and the same belt changed after it fails costs 3.4. That is $110.40 a time in labour alone, and finding the wear early is what the inspection task is for.
Questions people ask about machine maintenance
How do we know a machine's intervals?
Start with the manufacturer's manual for the duty it assumed, adjust for yours, and then move them on what your own checks find over a couple of cycles.
Is cleaning really maintenance?
It is inspection with a rag in your hand. Almost every early fault indicator on a machine is visible to somebody who is cleaning it and invisible to somebody walking past.
What about machines with no manual?
Common with inherited plant. Start conservative, record findings carefully, and let the first year of evidence set the interval. Write down that this is what you are doing.