Planned Maintenance or Planned Interval Maintenance (PNM) or (PIM)

This is also known as Systematic Maintenance or Regular Plant Maintenance. The duration of the maintenance and the checking parameters are predetermined in following four different intervals:

• Inspection (I),
• Minor or Small repairs/overhaul (S),
• Medium repair/overhaul (M), and
• Major repair or Complete overhauls (C).

Inspection (I) is the external inspection carried out on daily basis which takes a very little time (about 5 minutes approximately).

Small or Minor Repairs/Overhauls (S) are carried out on the spot or on weekly basis without effecting production time. Simple adjustments lubrication, etc. are performed and this takes very less time, ranging from 15 minutes to 2 hours.

Medium Repairs (M) are carried out on monthly or quarterly basis. Partial dismantling, replacing worn-out parts, readjustments, accuracy checkups, etc. are taken care. This type, of work generally takes half man-day to one-man day (i.e. 4 hours to 8 hours).

Complete or Major Repair/Overhauls (C) is largest planned/preventive maintenance, which involves in complete dismantling the equipment and replacement/reconditioning, etc. are carried out. They are assembled again and tested for accuracy. This maintenance is taken up on half yearly or yearly basis and usually takes 1 to 3 days.

Apart from the above regular activities, some occasional activities such as the alterations and installations of new machines are also included in this maintenance.

Regular plant maintenance is suitable where the standby machines are available or when there is no work or insufficient work on the machine. This type of maintenance gives many advantages by reducing the cost of breakdown maintenance, downtime, and spare parts control, rejections and catastrophic failures. This maintenance is performed on time scale irrespective of the condition of machine with the checklists, prepared for the purpose. When such maintenance is carried out, it may so happen that some machines, which are in good conditions, may also have to be handed over to the maintenance and suffer the production. And if the alignment or assembly is not adjusted properly, the machine breakdown within a short period.