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A spare part, spare, service part, repair part, or replacement part, is an interchangeable part that is kept in an inventory and used for the repair or refurbishment of defective equipment/units. Spare parts are an important feature of logistics engineering and supply chain management, often comprising dedicated spare parts management systems.
Spare parts are an outgrowth of the industrial development of interchangeable parts and mass production.
In an industrial environment, spare parts are described in several manner to distinguish key features of various spare parts. The following describes spare part types and their typically functionality.
1. Capital parts are spare parts which, although acknowledged to have a long life or a small chance of failure, would cause a long shutdown of equipment because it would take a long time to get a replacement for them. Capital parts are typically repaired or replaced during planned overhauls/scheduled inspections. As description implies, these Capital Parts are typically expensive and are depreciated over time.
Examples of capital parts include pumps and motor sets used in industrial plants, or impeller or a rotor required for a pump or motor. This “spare” requirement would be determined by redundancy of equipment used in the industrial processes.
2. Consumables can be divided into two groups:
3. Inspection spares or outage spares typically refer to those spare parts used in conjunction with Capital Parts during planned overhauls/scheduled inspections and maybe reused but typically are not repairable and are discarded after removal from use if Inspection Spares are damaged. These Inspection Spares are sometimes mis-characterized as Capital spares (vs Capital Parts) and are also confounded with Inspection Consumables, which must be replaced at every inspection/outage. (an example of inspection spares would be bearings and mechanical seals, large bolts and nuts.)
4. Operational spares typically refer to those spare parts that are used during operation of equipment and would not require planned overhauls/scheduled inspections to replace. In an industrial setting, operational spares would be gages, valves (solenoid, MOVs that are in redundancy), transmitters, I/O boards, small AC/DC power supplies, etc.) (for a car, it would windshield wiper)
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 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.
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. [1]
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.
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.
AftermarketParts: 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. [2]
There is no UK or EU legislation which states that spare parts have to be available for any set period of time, [3] but some trade associations require their members to ensure products are not rendered useless because spare parts are not available. [4] The 'six year rule' in the UK Sale of Goods Act 1979 relates to the time period for enforcing claims that goods were defective when sold, not to whether spare parts are available to repair them, and section 23(3) of the Consumer Rights Act 2015 states that a consumer cannot require a trader to repair or replace goods if "the repair or replacement is impossible", implying that if spare parts are no longer available the consumer's Right to Repair (or to have a spare part supplied) would be lost. [5]
From the perspective of logistics, a model of the life cycle of parts in a supply chain can be developed. This model, called the repair cycle, consists of functioning parts in use by equipment operators, and the entire sequence of suppliers or repair providers that replenish functional part inventories, either by production or repair, when they have failed. Ultimately, this sequence ends with the manufacturer. This type of model allows demands on a supply system to ultimately be traced to their operational reliability, allowing for analysis of the dynamics of the supply system, in particular, spare parts.
When stockout conditions occur, cannibalization can result. This is the practice of removing parts or subsystems necessary for repair from another similar device, rather than from inventory. The source system is usually crippled as a result, if only temporarily, in order to allow the recipient device to function properly again. As a result, operational availability is impaired.
Industrialization has seen the widespread growth of commercial manufacturing enterprises, such as the automotive industry, and later, the computer industry. The resulting complex systems have evolved modular support infrastructures, with the reliance on auto parts in the automotive industry, and replaceable computer modules known as field-replaceable units (FRUs).
Military operations are significantly affected by logistics operations. The system availability, also known as mission capable rate, of weapon systems and the ability to effect the repair of damaged equipment are significant contributors to the success of military operations. Systems that are in a mission-incapable (MICAP) status due lack of spare parts are said to be "awaiting parts" (AWP), also known as not mission capable due to supply (NMCS).
Because of this sensitivity to logistics, militaries have sought to make their logistics operations as effective as possible, focusing effort on operations research and optimal maintenance. Maintenance has been simplified by the introduction of interchangeable modules known as line-replaceable units (LRUs). LRUs make it possible to quickly replace an unserviceable (failed) part with a serviceable (working) replacement. This makes it relatively straightforward to repair complex military hardware, at the expense of having a ready supply of spare parts.
The cost of having serviceable parts available in inventory can be tremendous, as items that are prone to failure may be demanded frequently from inventory, requiring significant inventory levels to avoid depletion. For military programs, the cost of spare inventory can be a significant portion of acquisition cost.
In recent years, the United States Department of Defense (DoD) has advocated the use of performance-based logistics (PBL) contracts to manage costs for support of weapon systems.[ citation needed ]
An original equipment manufacturer (OEM) is generally perceived as a company that produces parts and equipment that may be marketed by another manufacturer. The term is also used in several other ways, which causes ambiguity. It sometimes means the maker of a system that includes other companies' subsystems, an end-product producer, an automotive part that is manufactured by the same company that produced the original part used in the automobile's assembly, or a value-added reseller.
Logistics is the part of supply chain management that deals with the efficient forward and reverse flow of goods, services, and related information from the point of origin to the point of consumption according to the needs of customers. Logistics management is a component that holds the supply chain together. The resources managed in logistics may include tangible goods such as materials, equipment, and supplies, as well as food and other consumable items.
The technical meaning of maintenance involves functional checks, servicing, repairing or replacing of necessary devices, equipment, machinery, building infrastructure, and supporting utilities in industrial, business, and residential installations. Over time, this has come to include multiple wordings that describe various cost-effective practices to keep equipment operational; these activities occur either before or after a failure.
Inventory or stock refers to the goods and materials that a business holds for the ultimate goal of resale, production or utilisation.
A line-replaceable unit (LRU), lower line-replaceable unit (LLRU), line-replaceable component (LRC), or line-replaceable item (LRI) is a modular component of an airplane, ship or spacecraft that is designed to be replaced quickly at an operating location. The different lines (distances) are essential for logistics planning and operation. An LRU is usually a sealed unit such as a radio or other auxiliary equipment. LRUs are typically assigned logistics control numbers (LCNs) or work unit codes (WUCs) to manage logistics operations.
Purchasing is the procurement process a business or organization uses to acquire goods or services to accomplish its goals. Although there are several organizations that attempt to set standards in the purchasing process, processes can vary greatly between organizations.
A distribution center for a set of products is a warehouse or other specialized building, often with refrigeration or air conditioning, which is stocked with products (goods) to be redistributed to retailers, to wholesalers, or directly to consumers. A distribution center is a principal part, the order processing element, of the entire order fulfillment process. Distribution centers are usually thought of as being demand driven. A distribution center can also be called a warehouse, a DC, a fulfillment center, a cross-dock facility, a bulk break center, and a package handling center. The name by which the distribution center is known is commonly based on the purpose of the operation. For example, a "retail distribution center" normally distributes goods to retail stores, an "order fulfillment center" commonly distributes goods directly to consumers, and a cross-dock facility stores little or no product but distributes goods to other destinations.
Remanufacturing is "the rebuilding of a product to specifications of the original manufactured product using a combination of reused, repaired and new parts". It requires the repair or replacement of worn out or obsolete components and modules. Parts subject to degradation affecting the performance or the expected life of the whole are replaced. Remanufacturing is a form of a product recovery process that differs from other recovery processes in its completeness: a remanufactured machine should match the same customer expectation as new machines.
Integrated logistics support (ILS) is a technology in the system engineering to lower a product life cycle cost and decrease demand for logistics by the maintenance system optimization to ease the product support. Although originally developed for military purposes, it is also widely used in commercial customer service organisations.
A field-replaceable unit (FRU) is a printed circuit board, part, or assembly that can be quickly and easily removed from a computer or other piece of electronic equipment, and replaced by the user or a technician without having to send the entire product or system to a repair facility. FRUs allow a technician lacking in-depth product knowledge to isolate faults and replace faulty components. The granularity of FRUs in a system impacts total cost of ownership and support, including the costs of stocking spare parts, where spares are deployed to meet repair time goals, how diagnostic tools are designed and implemented, levels of training for field personnel, whether end-users can do their own FRU replacement, etc.
Mobile asset management is managing availability and serviceability of assets used to move, store, secure, protect and control inventory within the enterprise and along the supply chain or in conjunction with service providing.
An automobile repair shop is an establishment where automobiles are repaired by auto mechanics and technicians. The customer interface is typically a service advisor, traditionally called a service writer.
Equipment rental, or plant hire, is a service industry providing machinery, equipment and tools for a limited period of time to final users, mainly to construction contractors but also to industry and individual consumers. Renting can be defined as paying someone for the use of something for temporary or short-term purposes.
In the United States Navy, Refueling and Overhaul (ROH) refers to a lengthy refitting process or procedure performed on nuclear-powered naval ships, which involves replacement of expended nuclear fuel with new fuel and a general maintenance fix-up, renovation, and often modernization of the entire ship. In theory, such process could simply involve only refueling or only an overhaul, but in practice, nuclear refueling is always combined with an overhaul. An ROH usually takes one to two years for submarines and up to almost three years for an aircraft carrier, performed at a naval shipyard. Time periods between ROHs on a ship have varied historically from about 5–20 years (for submarines) to up to 25 years (for Nimitz-class aircraft carriers). For modern submarines and aircraft carriers, ROHs are typically carried out about midway through their operating lifespan. There are also shorter maintenance fix-ups called availabilities for ships periodically at shipyards. A particularly lengthy refueling, maintenance, and modernization process for a nuclear aircraft carrier can last up to almost three years and be referred to as a Refueling and Complex Overhaul (RCOH).
Sierra Army Depot (SIAD) is a United States Army post and military equipment storage facility located near the unincorporated community of Herlong, California. It was built in 1942 as one of several ammunition storage facilities located far enough inland to be safe from Japanese attack, yet close enough to western military posts and ports to facilitate shipment of supplies. The site also met the requirement that the depot be in a dry and isolated area.
Pay on production (PoP) is a special build-operate-transfer (BOT) model, where payment is made to a supplier by the original equipment manufacturer (OEM) per piece produced on the supplier's own equipment by the OEM's employees.
Level of Repair Analysis (LORA) is used as an analytical methodology used to determine where an item will be replaced, repaired, or discarded based on cost considerations and operational readiness requirements. For a complex engineering system containing thousands of assemblies, sub-assemblies, components, organized into several levels of indenture and with a number of possible repair decisions, LORA seeks to determine an optimal provision of repair and maintenance facilities to minimize overall system life-cycle costs.
Cannibalization of machine parts, in the maintenance of mechanical or electronic systems with interchangeable parts, refers to the practice of removing parts or subsystems necessary for repair from another similar device, rather than from inventory, usually when resources become limited. The source system is usually crippled as a result, perhaps only temporarily, in order to allow the recipient device to function properly again.
Tool management is needed in metalworking so that the information regarding the tools on hand can be uniformly organized and integrated. The information is stored in a database and is registered and applied using tool management. Tool data management consists of specific data fields, graphics and parameters that are essential in production, as opposed to managing general production equipment.
The term power assembly refers to an Electro-Motive Diesel (EMD) engine sub-assembly designed to be "easily" removed and replaced in order to restore engine performance lost to wear or engine failure. Typical of heavy-duty internal combustion engines used in industrial applications, EMD engines are designed to allow the cylinder liners, pistons, piston rings and connecting rods to be replaced at overhaul without removing the entire engine assembly from its application location. This increases engine value, reduces downtime and allows the engine to be returned to true new engine performance. Other terms such as cylinder pack, liner pack, cylinder assembly and cylinder kit are used in the engine industry to describe similar assemblies. In the large-engine industry, the term "power assembly" has also become generic and is often used to refer to the assemblies used in non-EMD engines where "power pack" may be the preferred term, although both terms are functionally the same.