ASTM_B_966_-_10.pdf

Designation:B96610Standard Test Method forPermeability of Powder Metallurgy(PM)Bearings UsingNitrogen Gas1This standard is issued under the fixed designation B966;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of the perme-ability of a PM bearing when subjected to pressurized nitrogenunder controlled conditions.1.2 The values stated in SI units are to be regarded as thestandard with the exception of flow rate for which the cm3/minunit is the industry standard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2B243 Terminology of Powder MetallurgyE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 IEEE/ASTM Standards:IEEE/ASTM SI-10 American National Standard for Use ofthe International System of Units(SI):The Modern MetricSystem3.Terminology3.1 Definitions of powder metallurgy(PM)terms can befound in Terminology B243.Additional descriptive material isavailable in the Related Materials section of Volume 02.05 ofthe Annual Book of ASTM Standards.4.Summary of Test Method4.1 Bearings are sampled and dried.4.2 A bearing is sealed between two plates and nitrogen isintroduced into the inner diameter(ID)of the bearing at astandard pressure.4.3 Nitrogen flow through the bearing is measured using aseries of rotameters(common tapered glass tube flow meters).5.Significance and Use5.1 In service,there is a space between a shaft and aself-lubricating PM bearing that contains an oil film when thebearing is operating properly.In the event the oil film isdisrupted or fails to form the bearing will exhibit increasedwear and possibly fail.Therefore the ability for oil to flowthrough the porosity of a PM bearing is critical to theperformance of the bearing.5.2 The porosity of the bearing must be open to the surfaceand interconnected within the bearing.This allows the oil in aself-lubricating PM bearing to flow during operation to thespace between the bearing and the shaft to form an oil film andprotect the shaft from wear.5.3 The ability of a gas to flow through the bearing reflectsthe openness and interconnected properties of the porosity inthe bearing.5.4 Data from this test can be used as an internal quality tooland can be reported to buyers of bearings.5.5 Anumber of other factors also affect the performance ofthe bearing and the movement of oil;factors such as the oilviscosity,operating temperature,load,shaft speed,surfacearea,surface finishes and others.This test provides informationon only one property and cannot be the sole consideration inthe design and testing of a bearing application.6.Apparatus6.1 Source of pressurized air(700 6 140 kPa).6.2 Source of pressurized nitrogen(200 6 34.5 kPa).6.3 Rotameters(calibrated at 34.5 6 0.34 kPa)Rotameter 1 0-50 cm3/minRotameter 2 0-500 cm3/minRotameter 3 0-2500 cm3/minRotameter 4 0-50000 cm3/min1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibility of Subcom-mittee B09.04 on Bearings.Current edition approved May 1,2010.Published June 2010.DOI:10.1520/B0966-10.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.3.1 Readability at maximum flow:Rotameter 1 2 cm3/minRotameter 2 5 cm3/minRotameter 3 25 cm3/minRotameter 4 200 cm3/minNOTE1Rotameters are manufactured using specific conditions andgases resulting in flows and readability that differ slightly from thosefound when performing an actual test.Acalibration done at the conditionsused in the actual testing will yield either a calculation or a conversionchart to correct the readings to the actual flows.6.4 Pressure gauges/regulators and suggested capacities.6.4.1 Incoming air regulator(minimum capacity 830 kPa).6.4.2 Nitrogen regulator(minimum capacity 100 kPa).6.4.3 Air to clamping device(700 6 140 kPa).6.4.4 Nitrogen to test piece(34.5 6 0.34 kPa).6.5 Device for clamping bearings between two plates.6.6 Tubing and valves as needed.6.7 The following figures are of a typical permeability testapparatus.These do not represent the only design capable ofperforming this test.7.Sample Preparation7.1 Thirty sample bearings shall be obtained randomly fromthe