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Bearing Raceway Honing

by Rick Mathis on October 24th, 2012

Engineers have long acknowledged that a series of balls rolling in a raceway is the most efficient means of minimizing friction between moving surfaces. This recognition has led to the use of anti-friction ball bearings in numerous applications from tiny precision instruments to huge machinery of all types

As bearing loads and operating speeds increased, functional characteristics of the ball raceway surfaces became correspondingly critical. At the same time, the demand for ball bearings followed a steady upswing. It was apparent there was a need for a process that would generate greater accuracy on a more productive scale than offered by the methods that were currently being used at the time.

Micromatic research and development of Microhoning techniques along these lines produced the first successful method for automatic processing and handling of raceway rings on multiple spindle machines. Production increased several times over the output of former methods. Even more significant was the ability of the Microhoning process to improve these raceway functional characteristics:
1) Curvature – true path across raceway;
2) Macro geometry – waviness around the raceway;
3) Micro geometry – surface roughness and lay of the raceway.

Processing economies were also affected. Microhoning capabilities made it possible to reduce grinding time and to eliminate polishing operations.

Since the quality of any bearing can be no better than the surface on which the balls roll, the slightest imperfections in the raceways tend to increase friction and noise, as well as reduced bearing life.

The noise that a bearing emits when rotated under load is more than an indication of surface condition and how smoothly the balls roll. It is an important functional factor in itself, especially in such instances as mounted type bearing used in industrial fan applications. Because the fans are usually mounted on structural steel and there is duct work around them, the noise of these fans is amplified several times over its natural level.

Quieter running, longer life bearings result from Microhoning’s ability to:
1) improve concentricity between raceway and bore;
2) remove high spots in raceways and true the plane of the track;
3) correct track curvature for a greater degree of contact with balls;
4) simultaneously improve both accuracy and surface finish.

Although the generation of torus-shaped surface of a bearing raceway might be considered a unique application of Microhoning, the above results are achieved through adaptation of basic Microhoning principles. Primarily, they are (a) a combination of motions that generates more accurate geometric form and keeps the abrasive stick self dressing, (b) low-velocity abrading with controlled pressure, (c) a float (in the tool) which allows the abrasive stick to align itself with the ball track.

Both inner and outer raceways are Microhoned on multiple spindle machines. The number of spindles is dependent upon the size of the bearing and production required. Positioned on an oscillating arm, the tools pivot about the center of the raceway arc. As the rings rotate, the abrasive sticks sweep across the tracks, removing irregularities and leaving a surface clean of smeared or deformed metal.

Techniques for locating, holding and rotating the rings are continually being improved to assure more uniform wall thickness and greater accuracy.

Through critical checks and comparative performance studies, bearing makers and users are convinced that bearings with Microhoned raceways run smoother, quieter and longer than those processed by any other method.

Although refinements in equipment and methods are always under constant cultivation, Microhoning on a production basis has been economically feasible for many years. Many very prominent bearing manufactures are currently utilizing the Microhoning process on a production basis.

Whether you need new raceway honing equipment or you would like to refurbish/retool your existing Micromatic Microhoning machines, Kenrie can help. Contact us through our website or call us at 616-494-3200.

From → Re-tools

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