ASTM D3337 method for determining life and torque of lubricating greases
ASTM D3337 standard test method for determining life and torque of lubricating greases in small ball bearings
5. Apparatus
5.1 The apparatus required for this test method is described in detail in Annex A1. A new R-4 bearing is used for each test. It is run at 12 000 r/min 1/2-lbf (2.2-N) radial load and 5-lbf (22-N) axial load.
6. Reagents and Materials
6.1 Grease Sample - Procure the grease sample from below the surface of the grease container. Do not let separated oil get in contact with the sample; pour the excess oil off if present. Screen the grease using a 40-µm retention filter. A technique for screening is described in Annex A2.
6.2 Test Bearing:
6.2.1 Specifications - the test bearing is size R-4.
6.2.2 Size - 0.2500 in. (6.350 mm) bore, 0.6250 in. (15.875 mm) OD, 0.1960 in. (4.978 mm) wide.
6.2.3 Material - Type 440C stainless steel, heat stabilized.
6.2.4 Precision Class - AFBMA (Anti-Friction Bearing Manufacturers Association) Class 7.
6.2.5 Radial Clearance - 0.0003 to 0.0005 in. (0.007 to 0.013 mm).
6.2.6 Retainer - stainless steel ribbon type.
6.2.7 Shields - removable with snap rings.
6.2.8 Packaging - bearing, shields, and snap rings packaged individually in clean and sealed envelopes.
7. Grease Packing of Test Bearing
7.1 Pack the test bearing in a clean environment with a quantity of test grease to fill one third of the free space in the bearing.
7.2 If it is necessary to determine the free space of a weighed bearing, place the bearing (with shields and snap rings removed) in a container of melted petrolatum of known density under vacuum. Let the petrolatum harden, remove bearing, and replace shields and snap rings. Clean the bearing of excess petrolatum and determine the weight increase. Using the density of petrolatum and bearing weight increase, compute the bearing free space. For the Barden bearing No. SR4SSW4, the one-third free space is 0.080 mL.
7.3 The test bearing may be packed on either a weight or a volume basis. A small spatula or a small syringe with a short needle can be used to place the test grease between the balls on both sides of the test bearing.
7.4 If the test bearing is packed on a weight basis, the density of the grease must be known in order to compute the weight of test grease equivalent to one-third the free space in the test bearing.
7.5 Immediately after packing the test grease in the test bearing, install the shields and snap rings. Then turn the bearing 100 revolutions in each direction at less than 200 r/min to distribute the test grease.
