AIA/NAS 661-2012 pdf download BEARINGS, BALL AND ROLLER, ROD END, ANTI- FRICTION, AIRFRAME
3. REQUIREMENTS
3.1 Materials.
3.1 .1 Metals. The steel used shall be such that the finished bearings will meet the requirements specified herein. The manufacturer shall use due care in subjecting the steel used to suitable check analysis and physical tests to satisfy the purchaser as to the steel used.
3.1 .2 Filled Epoxy Base Filler. When required by the appropriate code letter in the NAS Standard, the bearing shall be filled to within .062 of the shank end with Crest 31 1 9 Resin and Crest 71 03 curing agent as manufactured by the Crest Products, Co., Fountain Valley, CA. The mixing proportion of the resin-to-curing agent shall be 1 00:6.5 by weight. As an alternate filler use Hysol Resin RE-2038 with hardener HD-3475 manufactured by the Hysol Division, Dexter Corporation, Olean, New York. The mixing ratio by weight of RE-2038/HD-3475 is 1 00/25. The cured epoxy base filler shall withstand temperatures of –67 ºF to 250 ºF without excessive shrinkage or cracking.
3.2 Design and Construction. The bearings shall be of such design and construction as to meet the requirements specified herein. Except as otherwise specified, the details of the working parts shall be optional.
3.2.1 Raceways. The raceways of the inner and outer rings shall be of single piece construction.
3.3 Closures. Closures shall be provided to prevent the entrance of dust and to retain the lubricant throughout the range of temperature specified herein.
3.3.1 Type. The material of the sealed closure shall be a composition contact seal which will operate satisfactorily at conditions specified in Section
4. Closures of the seal type shall be readily removable by service activities for inspection and relubrication of the bearings, and shall be of such construction that they may be replaced without difficulty. Enclosures shall withstand temperatures of (–67 ºF to 250 ºF) without warpage or embrittlement which will prevent retention of the lubricant. Closures shall be compatible with the lubricant specified herein. 3.4 Dimensions and Tolerances. Dimensions and tolerances shall be as specified on the applicable NAS drawings.
3.5 Finish. The faces of inner ring shall have a smooth finish that will not exceed 63 microinches Ra per ASME B46.1 .
3.5.1 Races. The inner raceway and rolling elements shall be through-hardened. The outer raceway shall be hardened from a minimum of 1 5 percent to a maximum of 50 percent of the raceway thickness. The raceway and rolling elements shall have a high-grade lapped surface finish that will not exceed 8 microinches Ra per ASME B46.1 .
3.6 Hardness.
3.6.1 Metal Shank. The rod end metal shank shall have a uniform cross-sectional hardness and have a tensile strength between 1 25 KSI minimum and 1 80 KSI maximum.
3.6.2 Epoxy Base Filler. The epoxy base filler shall have a Barcol hardness between 30 minimum and 40 maximum.
AIA/NAS 661-2012 pdf download
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