From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Article from 'The Dragon' publication on an Air Draw Furnace using Fafnir Cylindrical Cartridges in a recirculating tempering unit.
| Identifier | ExFiles\Box 115\2\ scan0555 | |
| Date | 1st November 1940 guessed | |
| The DRAGON Air Draw Furnace Emphasizes Positive Control Fafnir Cylindrical Cartridges Employed In Eclipse Recirculating Tempering Unit THE MAKING of steel is a science in itself. In fact, one step alone in its fabrication—the process of heat treatment—has been the subject of much extensive study on the part of metallurgists. In brief, heat treatment consists of heating the steel to a point above its critical temperature and then quickly cooling it by quenching in a suitable medium, to obtain the desired hardness. However, this quenching operation may produce too excessive a hardness or brittleness for satisfactory use. It is the drawing operation, therefore, which overcomes these disadvantages. For this process, the steel is again heated, but this time below its critical temperature, which not only relieves the quenching strains but increases the toughness by removing some of the original hardness of the quench. Air furnaces, similar to the Rot-Air Draw Furnace, manufactured by the Eclipse Fuel Engineering Company, have become popular for this operation since they provide a uniform, positively controlled flow of hot air throughout the entire furnace charge. The Eclipse Rotair Air Draw Unit (a recirculating type of air rather than a simple steel plate or felt cartridge, is an integral part of the bearing itself. The design is made clear by the accompanying illustration. The two inner members, fixed in the bearing outer ring, form a trap for grease retention and dirt exclusion, while the outside plate, pressed on the inner ring, makes an effective slinger. Definite, though extremely close, tolerances exist between the individual members, and no rubbing contact material is employed, so that nothing is added to the total bearing friction. The outer member is of heavier stock for protection against abuse, and is treated to resist corrosion. RESULTS UNDER TESTS In accordance with the strict Fafnir creed that a new ball bearing should be “proved practical before proved first,” this new Mechani-Seal was subjected to over two years of experimentation and testing. A great many of these new Fafnirs were packed with different greases and run at varying speeds. In no case did the seals pump the lubricant from the bearing and, moreover, the greases, at the end of the gruelling tests, were found to be still in their original condition, and uncontaminated in any way. The Mechani-Seal Bearings were run in both horizontal- and vertical-position tests in specially designed, dust-filled “torture chambers.” Equivalent to thousands of hours of operation in normal service, these tests demonstrated the definite efficiency and worth of the Fafnir design over all other existing types of seals because the other designs failed at anywhere from ten to thirty hours, while the Mechani-Seal Bearings were still operating successfully at the end of each test. TYPES COMMERCIALLY AVAILABLE The Fafnir design is obtainable at present in a number of different variations—Single Seal (L Type), Double Seal (LL Type), Seal and Shield combinations (LD Type). This seal is applicable not only to standard Radial Type Bearings in the smaller sizes, but also to the well-known Fafnir Wide Inner Ring Bearing for positive mounting on shoulderless shafts. The outer ring can be furnished beveled on order, for self-alignment within correspondingly grooved housings. The wire-loc feature can likewise be supplied on order, providing a snap ring shoulder on the bearing outer ring for simplifying the mounting problem in certain more complicated assemblies. Backed by Fafnir’s quarter-century of experience and leading position in the industrial ball bearing field, this entirely new Mechani-Seal design constitutes a new development adding to the effectiveness of an already broad and popular line — in keeping with Fafnir’s policy of adapting its product to the needs of the user, and simplifying the entire problem in the process so far as humanly possible. [Image Captions] The fan shaft of the Air Draw Furnace is mounted on Fafnir Cylindrical Cartridges. Unretouched views of Mechani-Seal Bearings (with outer rings removed) after extensive operation in “Dust Box.” Notice clean and comparatively undisturbed condition of grease. 300 RPM 1000 RPM 2000 RPM | ||