Lube-Tech PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
intended to enhance energy efficiency by friction reduction. Obsolescence caused by outdated technology can be thus avoided.
A multitude of definitions are available for the term spare part: i. DIN 24420-1 Spare parts are “parts (e.g. also called individual parts), groups (e.g. also called assemblies and part groups) or complete products intended to replace damaged, worn or lacking parts, groups or products.”
ii. VDI 2892 (2019): “Spare parts serve to maintain the function and retain the value of machines and systems in use. Provision of tailored spare parts is an essential influencing parameter for the availability and thus the economic efficiency of such machines and systems.”
iii. Directive 2011/65/EU, article 3 (27) Spare part — Spare part means a separate part of an electrical and electronic equipment (EEE), that can replace a part of an EEE. The EEE cannot function as intended without that part of the EEE. The functionality of EEE is restored or is upgraded when the part is replaced by a spare part.
iv. Automotive Parts Remanufacturers Association (APRA) [3] Spare parts — Replaceable component, sub-as- sembly and assembly identical to and interchange- able with the item it is intended to replace. Note: Often called service part (in the US).
v. Basics of maintenance according to DIN 31051-2019 A spare part constitutes a part, component, device, subsystem, functional unit, operating equipment or system, which can be described and considered as intended to replace a corresponding object in order to maintain the originally required function of the object. Note: According to DIN 31051, a lubricant (operating equipment) can be described and
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considered as a spare part. Lubricants are integral elements of maintenance plans and intended for replacement as such.
vi. Federation of the German Construction Industry e.V [4] “Normal” spare parts are not subject to any particular wear and are usually replaced as part of repairs or ongoing maintenance.
In defence, the U.S. DoD uses different wordings and has wide range definitions, like repair part, any part, assembly, or component needed to repair or maintain an end item or a spare part is an item purchased for replacement, replenishment of stock or for use in the maintenance, overhaul, and repair of equipment. ISO 2710-2 (section 3.3.15) defines a spare part just as broadly as an individual component or assembly that is kept in stock.
The distinction between a wear part and a general spare part can be illustrated using a household appliance example. The housing/casing of a kitchen mixer that breaks when dropped is not normally considered a wear part, because it is not expected to deteriorate during normal use. However, it may still need to be replaced to restore the functionality of the product and is therefore considered a spare part.
Wear-out
In 1969, the OECD’s International Research Group on Wear of Engineering Materials (OECD-IRG) pointed out, that the distinction possible in German between “Verschleiß = wear” and “Abnutzung = wear + corrosion” (i.e., combined stress) does not exist in English, but the Dictionary of Lubrication Engineering translated “Abnutzung” as “wear out” [5].
Within the context of “wear”, DIN 31051:2019 introduces another term: wear reserve (see section 3.3.4, ibid) describes the reserve of possible functions implemented under specified conditions. Once the wear reserve has been depleted, the machine loses
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