Classification of Spare Parts

Spare Parts Management

There are no hard and fast rules to classification of the spare parts. Spare parts are usually classified as per the convenience of the department or the industry. However, the general nomenclature in spare parts classification is given below.   

Complete Equipment

Major Assemblies

Usually more costly, more life (comparable to the main equipment also).

Minor Assemblies

Comparatively less expensive, lesser life.

Capital Repair Spares or Insurance Spares (These are Critical Items)

Non-availability leads to very heavy downtime cost or may prove catastrophic or permanent damage with huge stock out cost. Lead time of procurement is too high.

Regular Maintenance/Breakdown Spares

These are required regularly and therefore, kept in stock in substantial numbers. Both the reliability and unit cost of these items are not very high, e.g. Belts, bearings, oil seals, etc.

Rotable/Floating Spares

Not always scrapped. But can be repaired and thus be used again. Costly spares like pumps, engines, motors propellers, etc. are repaired and stored because the stock out cost is high. This is observed with good practice in road transport departments, railways, shipping and air line sectors.

Overhauling Spares

These need overhauling at regular intervals, e.g. valves, coupling, gasket, etc.

Contingency Spares

These are interchangeable or an alternate method/technology may be available to take care of the situation, e.g. Rivets, Bolts, Valves, Gears.

Most often, the spare parts are classified for maintaining and controlling them in stores. Based on their usage, cost, significance of the item in the machine, importance of the machine in which it is used, availability in the market, etc. the more scientific and proven methods of analyses and classifications, known as selective inventory control techniques, are discussed in this unit through the following sections.

These are viewed from the angle of maintenance inventories and the explanation is given with reference to the maintenance stores only. Therefore, for further details, if required the readers may refer other relevant books (Materials Management/Inventory Control/Production and Operations Management/Operations Research, etc.)