A computerised maintenance management system (CMMS) is the software in which a building's or a site's maintenance team logs every repair and every scheduled service as a work order, assigns it, tracks it and records it against the machine it was done on. It handles the physical side of running a building. Hospitals, schools, factories, malls, offices and city governments all use one.
A CMMS rests on two lists. The first is the asset register, the list of every machine and fitting that needs maintenance: each chiller, lift, pump, generator, fire panel and air conditioner, with its location, maker and age. Each asset often carries a QR code sticker. The second is the list of work orders. A work order is a record of one job: what is wrong, which asset, who must fix it, by when, and what was done.
Work orders come from two places. Planned preventive maintenance (PPM) work orders come from a schedule. For example, each diesel generator, called a DG set in India, is serviced every 250 running hours, and the fire pumps are tested every week. Breakdown work orders come from someone reporting a fault.
Take, for example, a 600-bed hospital in Kolkata with about 4,500 assets in its register. At 3 p.m., a nurse finds that the air conditioner in a ward is not cooling. She scans the QR code on the unit with her phone and types "not cooling". The CMMS creates a work order, marks it high priority because patients are in the ward, and assigns it to the HVAC technician on duty. The target is four hours. The technician finds a blocked filter, cleans it, adds a photo and closes the work order at 4:40 p.m. The CMMS records the job against that unit. Its history now shows six repairs in twelve months. The maintenance manager uses that history to decide to replace the unit instead of repairing it again. The records also prove to inspectors that the hospital's equipment is maintained on schedule.
Work orders can also be opened by machines. The building automation system (BAS) can open one when a pump vibrates too much. Some CMMS products use these readings to predict a failure before it happens, which is predictive maintenance. When the job needs an outside contractor, a chain of shops or restaurants can order it through a facilities management marketplace.
How is a CMMS different from field service management (FSM) software? A CMMS is used by the owner or occupier of a building to look after its own assets. FSM is used by a service company, such as a lift maker, to send its technicians to many customers' sites. Larger industrial sites use asset performance management (APM) on top of a CMMS, to rank their machines by risk.