In most of the cases, it is better to have feeder bowls coated. Coatings can be either polyurethane spray coating, pasting of sheets on the bowl surface, teflon coating etc. The best solution lies in polyurethane spray coating. The advantages are firstly, in case of metallic components, the Noise Level can be drastically reduced by eliminating the Metal to Metal contact between the metallic bowl surface and the components. Another major problem faced by customers is of feeding oily components. Oily components reduce / eliminate the friction between the components and the Bowl track. As Vibrators work on the principle of Friction, this results in the components slipping and hence they are not able to feed properly. Proper type of coating can eliminate this. It is better to have a rough coating in case of oily components while in case of dry components, it is beneficial to have smooth coating. This improves the friction between the components and bowl, resulting in better movement of parts forward. Previously, PVC or polyurethane sheets were pasted to the bowl surface to act as lining. However, these have many disadvantages. First and foremost, in case the adhesion is not proper at any place, air bubbles get created and the whole sheet gets removed. Even if any adhesive is used, it gets removed in cases where there is oily residue on the components.

A few bowl feeder manufacturers in Europe have started using Polyamide bowls. These types of bowls have certain advantages like machining ease and repeatability but the disadvantages are the size (small) and type (conical). Step design bowls, which provide a lot of tooling flexibility, convenience and high loading volumes are not possible in case of polyamide bowls. Secondly, these bowls need to be machined on five axis CNC machines, making them costly to manufacture. However, in case the same bowl needs to be manufactured again, it is much easy to pull out the machining program and machine the bowl in the same way. However, some tooling needs to be hand made, which increases the labour content. Another advantage of polyamide bowls is that coating is not required as the bowl is not made of metal; the noise in case of metallic parts is less. Likewise, a disadvantage is that one cannot use oily parts on polyamide bowls as these bowls are smooth and the oily parts tend to slip and feeding is not proper. Hence, does it make sense to go for polyamide bowls? The answer is that only in case the parts are small and flat and many numbers of the same type of bowl are required.

Conical bowl is a bowl which is like a cone with the track welded to the inside of the cone. Conical bowls are required for certain types of components, which tend to overlap or are very flat. In these types 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 are most suitable for medical applications as firstly they can be welded in such a way that there is no crevice which can hold dust. Secondly, they can be fixed from the sides to result in much better working and to ensure that there is no dust present in the mounting holes for medical applications.

Most bowl feeder manufacturers usually use cylindrical bowls for most applications. The biggest advantage of cylindrical bowls is their low cost of construction, and tooling. Plus they are faster to make. However, the biggest disadvantage is that there are tracks one on top of one another, which results in jamming of parts between two tracks, removing of which requires manual intervention. Another disadvantage is that due to the tooling, especially in case of complicated tooling, the bowls becomes unwieldy and unbalanced. This results in the bowl not working properly on one side, resulting in either air jets required for pushing the parts forward at that particular area or else the minimum number of parts required in the bowl (for pushing the parts forward) increases. The loading quantity or the volume in cylindrical bowls too is much less, resulting in regular replenishment at short intervals. Though most bowl feeder manufacturers try to use cylindrical bowls, it is bound to create a lot of problems / hassles for the customer during long term usage. Hence, it is important to insist on the bowl feeder manufacturer not to use a cylindrical bowl and insist on a step / cascade type one. Some bowl feeder manufacturers call cylindrical bowls, outer pan types by having the orientation done on an outside track which is pitched downward to improve the separation and orientation of the parts. However, these become much more unwieldy and there is trouble with the parts moving properly at all places in the bowl, as indicated earlier. These too must be avoided. The best course of action is to ask the bowl feeder manufacturer to use a step / cascade type of bowl.

Vibrations have fascinated human beings since a very long time. Vibratory Bowl Feeders are around since the early part of the Twentieth Century. Till date no major alternative to a Vibratory Bowl Feeder has been invented. The only viable alternative is a Rotary Feeder which uses a motorised drive. However, it is definitely a very poor cousin of the Vibratory Bowl Feeder. For any part where a particular orientation is required, feeding through a vibratory bowl feeder is the only alternative. The first major distinction is that in a Rotary feeder, the parts which can be fed through a Rotary feeder are limited to certain flat caps where the diameter is more than the height, needles and rollers where the length is more than the diameter and any face can come out etc. As against this, in a vibratory bowl feeder almost any type of component can be handled. Second and most significant disadvantage of a Rotary feeder is that due to the positive pressure generated because of the rotating disc, the parts being fed are thrown against each other and against the wall of the feeder. This can result in damages to the parts. Compared to this, the parts do not get damaged in a vibratory bowl feeder. Even brittle and delicate parts can be handled in a vibratory bowl feeder. Thirdly, the speed or feed rate in case of a Rotary feeder can be as high as 40 metres per minute while that of a vibratory bowl feeder can be at the most 12 metres per minute. In fact, Elscint recently manufactured a Rotary feeder for flat drippers where the curved face was required to be up. A speed of 800 parts per minute was achieved for this 40 mm long flat dripper as against this, we could achieve a speed of just 200 parts per minute in case of a vibratory bowl feeder for the same component (for a different application where the speed requirement was much less). This is the only advantage of a Rotary feeder. Price of a vibratory bowl feeder is also much substantially less than that of a Rotary feeder.

Using a leveling screw for mounting stands made for vibratory bowl feeders is useful in many ways. First and foremost, it helps in leveling the stand in case the floor is not flat enough. In case the floor is not properly leveled, then the vibratory bowl feeder will be remains tilted on one side. This will result in the components not moving properly up the track in that area. If the orientation tooling is on that particular side, then the components will find it impossible to climb up on that side. The leveling screws help in reducing this possibility. Secondly, Elscint provides grouting arrangement on the leveling screws, which can help in grouting the stand to the ground. This is particularly useful in case of big vibratory part feeders, whose stands might have a tendency to jump / lose their position. Last but not the least, the leveling screws can help in providing a small height adjustment in case the stand does not have such a facility. Hence, it is always beneficial to have leveling screws for the mounting stands of vibratory bowl feeders.

The outlet height of a vibratory bowl feeder is between 100 mm to 500 mm, depending upon the model and the bowl used for the same. As a vibratory bowl feeder feeds to some machine or assembly operation, the required height, in the majority of the cases is more than this. Hence, there is a requirement of mounting the vibratory bowl feeder on a stand in order to match it with the machine or assembly table height. These stands can be cubical, single post, special, made of aluminum extruded sections etc. It always makes sense to purchase such stands from the bowl feeder manufacturer so that further work at the customer’s end is eliminated. In most of these stands, it is always beneficial to have a small extent of height adjustment. This ensures that minor adjustments at the time of integration are easy. In case the height adjustment required is just upto (+/-) 50 mm, this can be done by having this in the leveling screws below the stand. However, in most cases, the adjustment required is upto (+/-) 100 mm or even upto (+/-) 200 mm. This might be because the machine height is not finalized or if the bowl feeder is made to work for a variety of parts, with each part having a separate height requirement. In such a case, this adjustment can be provided with a height adjustment screw of appropriate length. Further in such a case, it is important that there is a provision to ensure that the screw does not rotate in 360 degrees, and proper provision is made for locking it. Elscint provides a keyway in the screw to ensure that it does not rotate and a proper locking arrangement is provided to ensure easy up and down movement as well as locking. The stands can be designed to not only mount the vibratory bowl feeder but also other things like hoppers, linear vibrators, gravity chutes etc. Further, if space is a constraint, one can opt for a single post stand which is a pillar type one as it helps conserve space. If not, then a cubical stand is most appropriate as it also provides some amount of storage space below the stand, where the tools and tooling of the vibratory bowl feeder can be stored.

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.