Older than the round bowl vibrator, the tub-type is rectangular in shape comparable to a traditional bath tub or horse trough. The primary difference between the bowl and tub is that these days tubs are generally dedicated to low volume production large parts finishing. A less fundamental difference of a practical nature is that as a general rule tub machines (unless of the through feed automated type) need to have the finished parts placed manually in the machines for finishing then removed the same way.
Tub vibrators can be used to finish very long parts, sometimes over 4000mm in length or the machines can be temporarily or permanently divided into a series of sections called compartments – the sizes of which can be varied longitudinally to suit varying component size.
When very long parts are involved, or more than one type of media is needed frequently tub units are often used.