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37-815: Wear in machine elements , together with other processes such as fatigue and creep , causes functional surfaces to degrade, eventually leading to material failure or loss of functionality. Thus, wear has large economic relevance as first outlined in the Jost Report . Abrasive wear alone has been estimated to cost 1–4% of the gross national product of industrialized nations. Wear of metals occurs by plastic displacement of surface and near-surface material and by detachment of particles that form wear debris . The particle size may vary from millimeters to nanometers . This process may occur by contact with other metals, nonmetallic solids, flowing liquids, solid particles or liquid droplets entrained in flowing gasses. The wear rate

74-489: A cylinder . Many mechanical design, invention, and engineering tasks involve a knowledge of various machine elements and an intelligent and creative combining of these elements into a component or assembly that fills a need (serves an application). ASTM International ASTM International , formerly known as American Society for Testing and Materials , is a standards organization that develops and publishes voluntary consensus technical international standards for

111-551: A machine . These elements consist of three basic types: While generally not considered to be a machine element, the shape, texture and color of covers are an important part of a machine that provide a styling and operational interface between the mechanical components of a machine and its users. Machine elements are basic mechanical parts and features used as the building blocks of most machines . Most are standardized to common sizes, but customs are also common for specialized applications. Machine elements may be features of

148-411: A cutting or plowing operation. Three-body wear occurs when the particles are not constrained, and are free to roll and slide down a surface. The contact environment determines whether the wear is classified as open or closed. An open contact environment occurs when the surfaces are sufficiently displaced to be independent of one another There are a number of factors which influence abrasive wear and hence

185-427: A part (such as screw threads or integral plain bearings) or they may be discrete parts in and of themselves such as wheels, axles, pulleys, rolling-element bearings , or gears. All of the simple machines may be described as machine elements, and many machine elements incorporate concepts of one or more simple machines. For example, a leadscrew incorporates a screw thread , which is an inclined plane wrapped around

222-429: A period of time fretting which will remove material from one or both surfaces in contact. It occurs typically in bearings, although most bearings have their surfaces hardened to resist the problem. Another problem occurs when cracks in either surface are created, known as fretting fatigue. It is the more serious of the two phenomena because it can lead to catastrophic failure of the bearing. An associated problem occurs when

259-424: A solid surface. Abrasive wear is commonly classified according to the type of contact and the contact environment. The type of contact determines the mode of abrasive wear. The two modes of abrasive wear are known as two-body and three-body abrasive wear. Two-body wear occurs when the grits or hard particles remove material from the opposite surface. The common analogy is that of material being removed or displaced by

296-446: A specific set of test parameter as stipulated in the test description. To obtain more accurate predictions of wear in industrial applications it is necessary to conduct wear testing under conditions simulating the exact wear process. An attrition test is a test that is carried out to measure the resistance of a granular material to wear. The Reye–Archard–Khrushchov wear law is the classic wear prediction model. The wear coefficient

333-479: A substantial waiting-list of producers seeking organizational memberships on the more popular committees. Members can participate without a formal vote and their input will be fully considered. As of 2015, ASTM has more than 30,000 members, including over 1,150 organizational members, from more than 140 countries. The members serve on one or more of 140+ ASTM Technical Committees. ASTM International has several awards for contributions to standards authorship, including

370-619: A wide range of materials, products, systems and services. Some 12,575 apply globally. The headquarters is in West Conshohocken, Pennsylvania , about 5 mi (8.0 km) northwest of Philadelphia . It was founded in 1902 as the American Section of the International Association for Testing Materials. In 1898, a group of scientists and engineers , led by Charles Dudley , formed ASTM to address

407-567: Is voluntary and is initiated by the member's request, not by appointment or invitation. Members are classified as users, producers, consumers, and "general interest". The latter includes academics and consultants. Users include industry users, who may be producers in the context of other technical commodities, and end-users such as consumers. To meet the requirements of antitrust laws, producers must constitute less than 50% of every committee or subcommittee, and votes are limited to one per producer company. Because of these restrictions, there can be

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444-537: Is a physical coefficient used to measure, characterize and correlate the wear of materials. Lubricant analysis is an alternative, indirect way of measuring wear. Here, wear is detected by the presence of wear particles in a liquid lubricant. To gain further insights into the nature of the particles, chemical (such as XRF, ICP-OES), structural (such as ferrography ) or optical analysis (such as light microscopy ) can be performed. Machine element Machine element or hardware refers to an elementary component of

481-401: Is affected by factors such as type of loading (e.g., impact, static, dynamic), type of motion (e.g., sliding , rolling ), temperature , and lubrication , in particular by the process of deposition and wearing out of the boundary lubrication layer. Depending on the tribosystem , different wear types and wear mechanisms can be observed. Types of wear are identified by relative motion ,

518-410: Is also called tribocorrosion . Impact wear is caused by contact between two bodies. Unlike erosive wear, impact wear always occurs at the same, well-defined place. If the impact is repeated, then usually with constant kinetic energy at the moment of impact. The frequency of impacts can vary. Wear can occur on both bodies, but usually, one body has significantly higher hardness and toughness and its wear

555-972: Is neglected. Other, less common types of wear are cavitation and diffusive wear. Under nominal operation conditions, the wear rate normally changes in three different stages: The wear rate is strongly influenced by the operating conditions and the formation of tribofilms . The secondary stage is shortened with increasing severity of environmental conditions, such as high temperatures, strain rates and stresses. So-called wear maps, demonstrating wear rate under different operation condition, are used to determine stable operation points for tribological contacts. Wear maps also show dominating wear modes under different loading conditions. In explicit wear tests simulating industrial conditions between metallic surfaces, there are no clear chronological distinction between different wear-stages due to big overlaps and symbiotic relations between various friction mechanisms. Surface engineering and treatments are used to minimize wear and extend

592-409: Is separated from the surface in the form of primary debris, or microchips, with little or no material displaced to the sides of the grooves. This mechanism closely resembles conventional machining. Fragmentation occurs when material is separated from a surface by a cutting process and the indenting abrasive causes localized fracture of the wear material. These cracks then freely propagate locally around

629-422: Is the hardness. Surface fatigue is a process in which the surface of a material is weakened by cyclic loading, which is one type of general material fatigue. Fatigue wear is produced when the wear particles are detached by cyclic crack growth of microcracks on the surface. These microcracks are either superficial cracks or subsurface cracks. Fretting wear is the repeated cyclical rubbing between two surfaces. Over

666-448: Is the load, α {\displaystyle \alpha } is the shape factor of an asperity (typically ~ 0.1), β {\displaystyle \beta } is the degrees of wear by an asperity (typically 0.1 to 1.0), K {\displaystyle K} is the wear coefficient, L {\displaystyle L} is the sliding distance, and H v {\displaystyle H_{v}}

703-458: Is the load, K {\displaystyle K} is the wear coefficient, L {\displaystyle L} is the sliding distance, and H v {\displaystyle H_{v}} is the hardness. Abrasive wear occurs when a hard rough surface slides across a softer surface. ASTM International defines it as the loss of material due to hard particles or hard protuberances that are forced against and move along

740-449: Is velocity, and n {\displaystyle n} is a velocity exponent. n {\displaystyle n} is typically between 2 - 2.5 for metals and 2.5 - 3 for ceramics. Corrosion and oxidation wear occurs both in lubricated and dry contacts. The fundamental cause are chemical reactions between the worn material and the corroding medium. Wear caused by a synergistic action of tribological stresses and corrosion

777-862: The ASTM International Award of Merit (the organization's highest award) ASTM International is classified by the United States Internal Revenue Service as a 501(c)(3) nonprofit organization. ASTM International has no role in requiring or enforcing compliance with its standards. The standards may become mandatory when referenced by an external contract, corporation, or government. In the United States, ASTM standards have been adopted, by incorporation or by reference, in many federal, state, and municipal government regulations. The National Technology Transfer and Advancement Act , passed in 1995, requires

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814-529: The components working life. Several standard test methods exist for different types of wear to determine the amount of material removal during a specified time period under well-defined conditions. ASTM International Committee G-2 standardizes wear testing for specific applications, which are periodically updated. The Society for Tribology and Lubrication Engineers (STLE) has documented a large number of frictional, wear and lubrication tests. Standardized wear tests are used to create comparative material rankings for

851-432: The density of "surface energy". Most solids will adhere on contact to some extent. However, oxidation films, lubricants and contaminants naturally occurring generally suppress adhesion, and spontaneous exothermic chemical reactions between surfaces generally produce a substance with low energy status in the absorbed species. Adhesive wear can lead to an increase in roughness and the creation of protrusions (i.e., lumps) above

888-423: The erosive wear on the inclination angle and material properties is provided in. For a given particle morphology, the erosion rate, E {\displaystyle E} , can be fit with a power law dependence on velocity: E = k v n {\displaystyle E=kv^{n}} where k {\displaystyle k} is a constant, v {\displaystyle v}

925-475: The federal government to use privately developed consensus standards whenever possible. The Act reflects what had long been recommended as best practice within the federal government. Other governments have also referenced ASTM standards. Corporations doing international business may choose to reference an ASTM standard. All toys sold in the United States must meet the safety requirements of ASTM F963, Standard Consumer Safety Specification for Toy Safety, as part of

962-411: The frequent rail breaks affecting the fast-growing railroad industry. The group developed a standard for the steel used to fabricate rails. In 1961, originally called the "American Society for Testing Materials" it was changed to "American Society for Testing And Materials". In 2001, ASTM officially changed its name to "ASTM International" and added the tagline "Standards Worldwide". In 2014,

999-519: The manner of material removal. Several different mechanisms have been proposed to describe the manner in which the material is removed. Three commonly identified mechanisms of abrasive wear are: Plowing occurs when material is displaced to the side, away from the wear particles, resulting in the formation of grooves that do not involve direct material removal. The displaced material forms ridges adjacent to grooves, which may be removed by subsequent passage of abrasive particles. Cutting occurs when material

1036-851: The nature of disturbance at the worn surface or "mechanism", and whether it effects a self regenerative or base layer. Wear mechanisms are the physical disturbance. For example, the mechanism of adhesive wear is adhesion . Wear mechanisms and/or sub-mechanisms frequently overlap and occur in a synergistic manner, producing a greater rate of wear than the sum of the individual wear mechanisms. Adhesive wear can be found between surfaces during frictional contact and generally refers to unwanted displacement and attachment of wear debris and material compounds from one surface to another. Two adhesive wear types can be distinguished: Generally, adhesive wear occurs when two bodies slide over or are pressed into each other, which promote material transfer. This can be described as plastic deformation of very small fragments within

1073-558: The original surface. In industrial manufacturing, this is referred to as galling , which eventually breaches the oxidized surface layer and connects to the underlying bulk material, enhancing the possibility for a stronger adhesion and plastic flow around the lump. A simple model for the wear volume for adhesive wear, V {\displaystyle V} , can be described by: V = K W L H v {\displaystyle V=K{\frac {WL}{H_{v}}}} where W {\displaystyle W}

1110-409: The properties of the surface being eroded. The impingement angle is one of the most important factors and is widely recognized in literature. For ductile materials, the maximum wear rate is found when the impingement angle is approximately 30°, whilst for non-ductile materials the maximum wear rate occurs when the impingement angle is normal to the surface. A detailed theoretical analysis of dependency of

1147-402: The small particles removed by wear are oxidized in air. The oxides are usually harder than the underlying metal, so wear accelerates as the harder particles abrade the metal surfaces further. Fretting corrosion acts in the same way, especially when water is present. Unprotected bearings on large structures like bridges can suffer serious degradation in behaviour, especially when salt is used during

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1184-496: The surface layers. The asperities or microscopic high points ( surface roughness ) found on each surface affect the severity of how fragments of oxides are pulled off and added to the other surface, partly due to strong adhesive forces between atoms, but also due to accumulation of energy in the plastic zone between the asperities during relative motion. The type of mechanism and the amplitude of surface attraction varies between different materials but are amplified by an increase in

1221-451: The surface through repeated deformations and cutting actions. It is a widely encountered mechanism in industry. Due to the nature of the conveying process, piping systems are prone to wear when abrasive particles have to be transported. The rate of erosive wear is dependent upon a number of factors. The material characteristics of the particles, such as their shape, hardness, impact velocity and impingement angle are primary factors along with

1258-560: The tagline changed to "Helping our World Work better." Now, ASTM International has offices in Belgium, Canada, China, Peru, Washington, D.C., and West Conshohocken, PA. In April of 2016, the Safety Equipment Institute (SEI) became a subsidiary of ASTM International. SEI is an accredited third-party certification organization that certifies various types of PPE to industry consensus standards. On June 9, 2022, it

1295-638: The wear groove, resulting in additional material removal by spalling . Abrasive wear can be measured as loss of mass by the Taber Abrasion Test according to ISO 9352 or ASTM D 4060. The wear volume for single-abrasive wear, V {\displaystyle V} , can be described by: V = α β W L H v = K W L H v {\displaystyle V=\alpha \beta {\frac {WL}{H_{v}}}=K{\frac {WL}{H_{v}}}} where W {\displaystyle W}

1332-577: The winter to deice the highways carried by the bridges. The problem of fretting corrosion was involved in the Silver Bridge tragedy and the Mianus River Bridge accident. Erosive wear can be defined as an extremely short sliding motion and is executed within a short time interval. Erosive wear is caused by the impact of particles of solid or liquid against the surface of an object. The impacting particles gradually remove material from

1369-467: Was announced that the European Committee for Standardization (CEN) and ASTM International agreed to extend and expand a Technical Cooperation Agreement from 2019. Membership in the organization is open to anyone interested in its activities. Standards are developed within committees, and new committees are formed as needed, upon request of interested members. Membership in most committees

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