TABLE OF CONTENTS Because of the high bulk density of steel media coupled with its low angle of repose, vibratory equipment design concepts must be modified when using steel media (Kittredge 1979). The media will not "roll" and "feed" like other media types because of the lack of frictional characteristics between the pieces and because of the low coefficient of friction between the media and the lining of the vibratory machine. The tub lining is the source of power to the media mass and, since the media is not abrasive, the media often skids on the lining as a bald tire would do on wet pavement.
Tub-type vibrators have not been successful in the ball burnishing market partly because of their lack of ability to roll the media mass, and also because of separation problems. Steel media flows so easily it is difficult to handle on a separating screen, which is external to the machine, and even more difficult to get back into the machine by means of a conveyor belt.
The round-type of vibratory machine, by its basic design, reduces the cross-sectional area of the steel media mass and has a built-in screen deck. The conveyorized handling of media is therefore eliminated. With steel media and its desire to flow, simplicity is an absolute must in equipment design. If the media never leaves the tub it eliminates the problem of returning it.
Most manufacturing engineers get a better appreciation for equipment design in steel burnishing applications when they...
