Linear vibrators or In-line rail feeder / vibrators are very useful when used along with a vibratory bowl feeder. However, many people do not know the advantages of using one. The major advantages of using a linear vibrator ahead of a vibratory bowl feeder are  –

1. In case a pick and place mechanism is used to pick up the parts oriented by the vibratory bowl feeder, the linear vibrator can convey the parts slightly ahead so that the pick and place mechanism does not foul with the periphery of the bowl. A non-vibratory part can be provided at the end of the linear vibrator from where the component can be picked up by the pick and place unit.
2. In case of feeding to a centreless grinding machine, the linear vibrator can be used to convey the components from the bowl to the grinding machine work rest. The linear track can generate the same and consistent pressure on the components and this can result in a very good finish quality of the components. Further no backpressure is required and hence even a single component can flow through at a very easy pace.
3. In case of linear track vis a vis a gravity / inclined chute, the overall height or the loading height of the vibratory bowl feeder can be reduced by as much as 300 mm.
4. The linear track can act as a buffer so that the machine to which the bowl feeder is feeding does not suffer for want of components.
5. In case extra push is required for feeding onto the machine to which the bowl feeder is feeding, the linear vibrator can generate that extra push. This can ensure the vibratory bowl feeder does not get burdened due to the extra long chutes. Extra long chutes on the bowl feeder can result in generating dead spans on the bowl, which in turn result in inconsistency of feeding.
6. The linear vibratory track can help in easy movement of parts from the bowl feeder onwards to the next machine. This helps in eliminating backpressure on the bowl feeder resulting in better feeding and performance.
7. The running cost of a linear vibrator is negligible (15 VA to 300 VA depending upon the model chosen).
8. The cost of the linear vibrator too is very low if compared to the total price of the feeding system.

Hence, in many cases, it makes sense to use a linear vibrator in addition to a vibratory bowl feeder.