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the process of removing burrs, scale, molding sand, and corrosion from the metal surfaces of small blanks and parts and for improving the surface quality of articles (polishing). It is performed in drums. To speed up the process, abrasive materials such as sand, emery, or corundum are put in the drum (dry tumbling), or sometimes various solvents are added (wet tumbling). For polishing in drums, sawdust or leather cuttings are sometimes put in with the objects being polished (dry polishing), or solutions of soap or alkali are added (wet polishing). Eccentrically mounted drums are used for better mixing.
In vibration tumbling the working chamber is oscillated in various directions with a frequency of 15-50 cycles per second; the vibration provides complex mixing of the parts and abrasive particles. When fastened to the drum, large parts may be treated by vibration tumbling.
In hydraulic tumbling, cold surface hardening takes place, increasing the fatigue resistance of the parts being treated. In this process the parts are fastened inside a chamber within which a liquid containing small metal shot is moving.
D. I. BRASLAVSKII and V. M. RASKATOV