There are two basic types of mass finishing – barrel tumbling and vibratory tumbling. Each of these mass finishing methods have pros and cons. There are also a number of sub-varieties which we will discuss in future posts.
Barrel tumbling might be more familiar if described as rock tumbling. Inside the tumbler the parts and media are lifted by the corners of the barrel and allowed to bump, scrape and slide against each other. The media used will depend on whether you are trying to deburr or polish your parts. Barrel tumbling is also good for part-on-part tumbling (another future post – so many posts and so little time). While typically used wet, barrel tumbling can also be a dry tumbling process. The big down side to barrel tumbling is the loading and unloading of parts.
Vibratory tumbling is a little different. Similar to barrel tumbling the parts and media are sliding against each but in more of a ‘filing’ motion. The tumbling action is occurring in 100% of the load with a vibe versus only 20-30% of the load in a barrel tumbler. This allows a vibrator (you know what I mean) to typically offer shorter cycle times. Vibratory tumbling can abrade and smooth a surface with minimal affect on the edges while barrel tumbling loves to round the edges. Vibratory tumblers can offer very simple and even automatic separation of parts and media.
Generally, barrel tumbling is good for durable parts that require heavy deburring or high polishing and for processes that use a lot of weight (i.e., tumbling with steel media). Vibratory tumbling is great for general purpose deburring, surface finishing and for easy loading/un-loading of parts.