In
logistics, spare parts can be broadly classified into two groups,
repairables and
consumables. Economically, there is a tradeoff between the cost of
ordering a replacement part and the cost of repairing a failed part. When the cost of repair becomes a significant percentage of the cost of replacement, it becomes economically favorable to simply order a replacement part. In such cases, the part is said to be "beyond economic repair" (BER), and the percentage associated with this threshold is known as the BER rate. Analysis of economic tradeoffs is formally evaluated using
level of repair analysis (LORA).
Repairable Repairable parts are parts that are deemed worthy of repair, usually by virtue of economic consideration of their repair cost. Rather than bear the cost of completely replacing a finished product, repairables typically are designed to enable more affordable maintenance by being more modular. That allows components to be more easily removed, repaired, and replaced, enabling cheaper replacement. Spare parts that are needed to support condemnation of repairable parts are known as
replenishment spares . A rotable pool is a pool of repairable spare parts inventory set aside to allow for multiple repairs to be accomplished simultaneously, which can be used to minimize
stockout conditions for repairable items.
Consumable ). Parts that are not repairable are considered consumable parts. Consumable parts are usually
scrapped, or "condemned", when they are found to have failed. Since no attempt at repair is made, for a fixed
mean time between failures (MTBF), replacement rates for consumption of consumables are higher than an equivalent item treated as a repairable part. Therefore, consumables tend to be lower-cost items. One example is in heavy machinery such as brake oils, hydraulic fluids, and belts. Because consumables are lower cost and higher volume,
economies of scale can be found by ordering in large lot sizes, a so-called
economic order quantity.
Commercial classification From a commercial perspective, spare parts can be classified into three main types:
OEM (original equipment manufacturer) parts: These parts are produced by the same manufacturer that made the original equipment.
Aftermarket parts: These are replacement parts made by companies other than the original manufacturer. They can serve as cost-effective substitutes for OEM parts.
Used or
second-
hand parts: These can be either OEM or aftermarket parts that have been refurbished and resold at a lower price. ==Legislation==