定价： 590元 加购物车

5.1 This test is a simple, effective way of determining the ability of bearings to roll freely. Most bearing manufacturers do not supply information on the breakaway friction coefficient of their products and if this is a design factor, users often buy candidate bearings and try them until they find one that appears to operate freer than the others. This test allows quantification of the breakaway friction characteristics of bearings. This test assesses the friction of a bearing as a tribosystem which includes its construction and lubrication. It has shown to correlate with use. If a bearing has a low breakaway angle in this test, its breakaway friction will be lower in service than the same size bearings that displayed a higher breakaway angle in this test.5.2 Breakaway friction of bearings is important in instruments where forces are light and the bearings are used as pivots rather than for continued rotation. Low friction is often imperative for proper device operation.5.3 Bearings with low breakaway friction are often sought for web handling rollers. Many rollers are driven only by tangential web contact and slippage can often damage the web. Low friction bearings are required.5.4 This test is useful for screening bearings for any applications where breakaway friction is a design concern.1.1 This test method is an extension of Test Method G164 and uses an inclined plane and a paperclip rider to detect the presence or absence of lubricants on the surfaces of flexible webs. A study to identify free spinning or low rolling friction bearings indicated that the paperclip friction test could be used for rolling friction by simply replacing the paperclip with a rolling element bearing on an axle. The angle of the inclined plane at initiation of rolling is the breakaway angle. This test method can be used to measure the angle at breakaway of small diameter (up to 100 mm outside diameter) rolling element bearings. The bearings that have been tested in the development of this method are conventional ball bearings with different separators, seals, and different conditions of lubrication (none, oil, greases, and so forth), but there is no technical reason why this test method would not work with bearings of other design, including plain bearings. Rolling element bearings like any sliding system can have friction characteristics at breakaway that are different than rolling continuously. As is the case with most inclined plane friction tests, the test only produces the friction characteristic at the onset of measurable rolling, using the angle (θ) when measurable rolling commences. The objective of this test is an assessment of breakaway rolling friction characteristics to assist machine designers in the selection of rolling element bearings for instrument pivots and the like where breakaway friction is a concern.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 加购物车

定价： 590元 加购物车

4.1 This practice covers bearings and bearing components of all material compositions and grades. It may be used to develop a process for adequately handling bearings.4.2 Unless the proper conditions of an adequate facility, equipment, and trained personnel are available, it may be better not to inspect the bearings in-house. The danger of contaminating and damaging the bearings may be much greater than the possibility of receiving bearings that will not function.4.3 Bearings are easily damaged at the customers' receiving and test areas. In most cases, bearings should be accepted based on the bearing manufacturer’s certification. Certificates of quality (conformance) supplied by the bearing manufacturer may be furnished in lieu of actual performance of such testing by the receiving activity of the bearings. The certificate shall include the name of the purchaser, contract number/PO number, name of the manufacturer or supplier, item identification, name of the material, lot number, lot size, sample size, date of testing, test method, individual test results, and the specification requirements.4.4 This practice does not cover clean room requirements of miniature and instrument precision bearings. These bearings require clean room environments in accordance with ISO 14644-1 and ISO 14644-2.1.1 This practice covers requirements for the handling of all bearings and bearing components.1.2 This is a general practice. The individual bearing handling requirements shall be as specified herein or as specified in the contract or purchase order. In the event of any conflict between requirements of this practice and the individual bearing requirements of an OEM drawing, procurement specification, or other specification, the latter shall govern. Many companies, organizations, and bearing users have excellent facilities, equipment, and knowledgeable personnel for handling bearings. The thrust of this practice is for users that do not have this knowledge of bearings.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 加购物车

定价： 590元 加购物车

定价： 590元 加购物车

1.1 This specification covers bridge bearings that consist of an unconfined polyether urethane rotational element subjected to compression loads, along with a resisting mechanism to transmit shear and/or tension loads through the bearing. For expansion and/or contraction applications, an additional stainless steel flat surface slides against a carbon steel plate faced with sheet polytetrafluoroethylene (PTFE). The function of the bearing is to transfer loads and to accommodate any relative movement, including rotation between a bridge superstructure and its supporting structure, or both.1.2 The requirements stated in this specification are the minimums necessary for the manufacture of quality bearing devices. It may be necessary to increase these minimum values due to other design or construction conditions.1.3 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 加购物车

5.1 This test method differentiates among greases having distinctly different low-temperature characteristics. This test is used for specification purposes and correlates with its precursor which has been used to predict the performance of greases in automotive wheel bearings in low-temperature service.5 It is the responsibility of the user to determine the correlation with other types of service.1.1 This test method covers the determination of the extent to which a test grease retards the rotation of a specially-manufactured, spring-loaded, automotive-type wheel bearing assembly when subjected to low temperatures. Torque values, calculated from restraining-force determinations, are a measure of the viscous resistance of the grease. This test method was developed with greases giving torques of less than 35 N·m at −40 °C.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 WARNING—Mercury has been designated by many regulatory agencies as a hazardous substance that can cause serious medical issues. Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Use Caution when handling mercury and mercury-containing products. See the applicable product Safety Data Sheet (SDS) for additional information. The potential exists that selling mercury or mercury-containing products, or both, is prohibited by local or national law. Users must determine legality of sales in their location.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 加购物车

This specification covers sintered bronze, oil-impregnated bearings made primarily from elemental copper, tin, lead, and graphite powders. This specification covers the following variables: Grades (available in three bronze base compositions identifiable by different graphite contents and one leaded bronze grade) and Type (Grades 1 and 2 are available in four types described by specific density ranges. Grade 3 is available in two types and Grade 4 is available in one type). Sintered bronze bearings shall be made by molding or briquetting metal powder mixtures to the proper density. The material shall conform to the required chemical composition for copper, tin, graphite, iron, lead, zinc, nickel, and antimony. The density of bearings supplied impregnated with lubricant shall be within the prescribed limits. Oil content of bearings shall not be less than the prescribed value for each grade and type of material. The material of different grades and types shall conform to the prescribed radial crushing strength requirements. An acceptance specification for the minimum bearing breaking load may be established for any specific standard oil-impregnated bearing. Chemical analysis shall be made for each representative sample of chips, which may be obtained by milling, drilling, filing, or crushing a bearing with clean dry tools without lubrication.1.1 This specification covers porous metallic sleeve, flange, thrust, and spherical bronze-base bearings that are produced from mixed metal powders utilizing powder metallurgy (PM) technology and then impregnated with oil to supply operating lubrication.1.2 Included are the specifications for the chemical, physical, and mechanical requirements of those bronze-base PM materials that have been developed and standardized specifically for use in the manufacture of these self-lubricating bearings.1.3 This specification is applicable to the purchase of bronze-base bearings (oil-impregnated) that were formerly covered by military specifications and are intended for government or military applications. Those additional government requirements that only apply to military bearings are listed in the Supplementary Requirements section of this specification.1.4 This specification accompanies Specification B439 that covers the requirements for Iron-Base Powder Metallurgy (PM) Bearings, (Oil-Impregnated).1.5 Typical applications for bronze-base bearings are listed in Appendix X1.1.6 Bearing dimensional tolerance data are shown in Appendix X2, while engineering information regarding installation and operating parameters of PM bearings is included in Appendix X3. Additional useful information on self-lubricating bearings can be found in MPIF Standard 35, ISO 5755 and the technical literature.21.7 With the exception of the values for density and the mass used to determine density, for which the use of the gram per cubic centimetre (g/cm3) and gram (g) units is the industry standard, the values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.8 The following safety hazards caveat pertains only to the test methods described in this specification. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 843元 加购物车

定价： 590元 加购物车

定价： 843元 加购物车

定价： 646元 加购物车

This specification covers the standard requirements for porous metallic sleeve, flange, thrust, and spherical iron-base bearings that are produced from mixed metal powder metallurgy technology and then impregnated with oil to supply operating lubrication. Porous iron-base bearings shall be produced by compaction of a mixture of elemental iron powder and copper, tin, pre-alloyed bronze or graphite powders and sintering in a furnace having a protective atmosphere at a specified time and temperature cycle. The interconnected or open porosity in the bearings shall be filled to the required volume either by an extended soaking in hot oil or preferably by a vacuum impregnation operation with lubricating oil which is a high-grade turbine oil with antifoaming additives and containing corrosion and oxidation inhibitors. Each of the iron-base bearing material shall conform to the chemical composition requirements for iron, carbon, graphite, copper, and tin as shall be determined by chemical analysis. The physical properties for each of the bearing material shall be within the prescribed wet density, oil content, and impregnation efficiency limits. The radial crushing strength and bearing breaking load of the oil-impregnated bearing material determined on a plain sleeve bearing or a test specimen prepared from a flange or spherical bearing shall also meet the minimum and maximum mechanical strength values.1.1 This specification covers the requirements for porous iron-base metallic sleeve, flange, thrust, and spherical bearings that are produced from metal powders utilizing powder metallurgy (PM) technology and then impregnated with oil to supply operating lubrication.1.2 Listed are the chemical, physical, and mechanical specifications for those standardized ferrous PM materials that have been developed specifically for the manufacture of self-lubricating bearings.1.3 This specification is a companion to Specification B438 that covers the requirements for porous oil-impregnated bronze-base bearings.1.4 Typical applications for self-lubricating iron-base PM bearings are discussed in Appendix X1.1.5 Commercial bearing dimensional tolerance data are shown in Appendix X2, while engineering information regarding installation and operating parameters of PM bearings is included in Appendix X3. Additional useful information on self-lubricating bearings can be found in MPIF Standard 35 (Bearings), ISO 5755, and the technical literature.21.6 Units—With the exception of the values for density and the mass used to determine density, for which the use of the gram per cubic centimetre (g/cm3) and gram (g) units is the long-standing practice of the PM industry, the values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not to be regarded as standard.1.7 The following safety hazards caveat pertains only to the test methods described in this specification. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 646元 加购物车

定价： 590元 加购物车

定价： 515元 加购物车