There are various types of bowls which can be used, namely, step, cylindrical, conical, outer track etc. All of these types have certain advantages and disadvantages inherent to their design & construction.

Cylindrical bowls – The biggest advantage is their low cost of construction and tooling. However, the disadvantage is that there are tracks one on top of another, which results in jamming of parts between two tracks, removing of which requires manual intervention. Another disadvantage is that due to tooling, especially in case of complicated tooling, the bowls becomes unwieldy and unbalanced. This results in the bowl not working properly on one side. The loading quantity or the volume in cylindrical bowls too is much less, resulting in regular replenishment at short intervals.

Step bowls - Step design bowls provide a lot of tooling flexibility, convenience and high loading volumes. Secondly, it is possible to provide irregular and complicated bowl tooling and shapes in case of step design bowls. As such there are no disadvantages of using step type bowls except that they are costlier to make. These can be used for any type of components. As there is no track on top of another, the problem of jamming of components between two tracks does not arise.

Conical bowls – Conical bowls are suitable only for certain types of components, which tend to overlap or are very flat. In these type of bowls too, as there is no track on top of another, the problem of jamming of components between two tracks does not arise. Conical bowls are most preferable in case of medical applications as they can be made to ensure there is welding crevice or gap anywhere in the bowl. Conical bowl can be fixed from the sides to result in much better working for medical applications.

Outer track bowls - These are also costlier to make but have some advantages like high loading capacity, optimum area for tooling. In case there is a requirement for high speed and complicated orientation, then outer track bowl is the only solution. However, the disadvantage is the high cost of such bowls. Further as the outer track bowl is an cylindrical bowl on the inside and therefore there are tracks one on top of another, which results in jamming of parts between two tracks, removing of which requires manual intervention.

Going through the above information, it can be concluded that step type bowl is the best for most parts being fed, not only from the point of view of the bowl tooler but also from the customer’s usage point of view.

In case of single coil vibratory bowl feeders, the coil is mounted centrally (either one coil or else two coils). The advantage is that one requires only a single coil, thus reducing the cost and secondly, the coil can be made powerful enough so that the same one can be used across models. However, there are certain major disadvantages of having a single or even two central coils. It leads to excessive vibrations at the centre, which reduce as the part moves away from the bowl centre. This results in a huge wastage of energy. Due to the eccentric and powerful load, there are possibilities of the springs and bolts breaking on a regular basis. To offset the extra load, the bowl needs to be made heavy or else extra counter weights need to be added to the bowl to balance it, further making the bowl needlessly heavy. The vibrations too are abnormal and heavy, resulting in damage to the parts being fed or resulting in a wrongly oriented part coming out. The bowl life too reduces due to this.

            In case of multiple coil vibratory bowl feeders, the coils are mounted on the periphery of the vibratory bowl feeder (three or four coils). However, for this the coils need to be correctly designed for each and every model. But the advantages are that firstly there is no extra energy wasted, thus saving on energy costs and secondly, the coils being on the periphery of the vibratory feeder, the vibrations are equally transferred to the bowl, leading to better performance of the vibratory bowl feeder. Secondly, being on the periphery, one can design the bowl having a slightly bigger diameter, which is not possible in case of a centrally mounted powerful coil. Further the chances of the springs and bolts breaking are drastically reduced, especially in the case of full wave vibratory bowl feeders. The bowl can be designed to be light weight and cast aluminium bowls can also be used. The life of the vibratory feeders and the bowl too is much more in case of multiple coils mounted at the periphery of the vibratory feeder.  

The number of components which can be loaded in a vibratory bowl feeder is limited either due to the volume or weight of the components. Volume is especially important in case of rubber or plastic components and weight when the components are metallic.

In case extra loading capacity is required, then the choice is to either use a bigger bowl feeder or else to use an auxiliary feeding unit like a flat vibratory hopper or elevator, silo etc. These auxiliary equipments can increase the loading quantity tremendously and the bowl feeder can become a totally man-less operation requiring refilling at longer intervals.

A Silo as well as a stock feeder is used to hold extra parts for replenishing the supply in a vibratory bowl feeder. While a stock feeder is set to operate automatically by a signal from a level control switch, thus eliminating either a deficiency or an over-supply of parts in the bowl, a Silo is mounted on the bowl itself and the components keep on percolating down from the bottom of the Silo into the bowl.

Thus a Silo and a stock feeder are competing products and while deciding on which one to opt for, the following points require consideration –

1.      Dimensions / sizes of the parts - In case of Silo, only certain parts like Needles, Rollers etc. It cannot be used for components like screws, hooks etc. Any size / dimension of parts can be accommodated in a hopper feeder.

2.      The disadvantage of Auxiliary Hoppers is the extra space which they occupy and plus the extra cost and electrical consumption and wiring required for the same. As against this, Silos offer the advantage of increased loading capacity and they do not require any Electrical Supply. The increase in height is also nominal. The overall Table size also does not increase to that extent.

Though the Silo has a lot of advantages, the only disadvantage is that it can only be used for certain components and this is its real limitation.