Many times one requires feeding components, one at a time and not one behind the other. Usually, components come out of the bowl feeder one behind another. For this purpose, a pneumatic escapement or singulator is required. It can work either mechanically through a cam operated system or else pneumatically by way of a single or double cylinder. The escapement or singulator stops one component and holds another. With a single stroke, one component is released while the one behind it is then stopped. This can find usage where the parts are to be packed in cartons, spouts are to be dropped into cartons, one part is to be picked up and operated upon. Further using an escapement with a gravity chute, one can use the stopped part for operations like drilling, tapping etc. The escapement can also be designed in such a way that on receipt of a signal from a relay / sensor or PLC, the escapement is actuated and a single component is released.

            Usually, most manufacturers use two pneumatic cylinders for these types of escapements, one for stopping one part and one for holding the part behind it. However, some manufacturers provide escapements which work on a single pneumatic cylinder. This results not only in saving the running cost but also the initial cost. Elscint, in fact, not only provides escapements with a single cylinder but also provides an F/R/L unit and solenoid valve along with all the electrical inputs like transformer and other circuitry so that using it becomes very hassle free and easy for the customer. The operation of this escapement can be with the help of a 24 V DC signal.

A Silo is an accessory which can be used along with a vibratory bowl feeder for providing higher capacities. Usually, the number of components which can be loaded in a vibratory bowl feeder is constrained by the weight and the volume of the components. In order to increase the loading capacity, usually auxiliary hoppers are provided. 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 like needles, rollers etc. It cannot be used for components like screws, hooks etc. The Silo sits on top of the bowl and is an integral part of the vibratory drive unit.

When it comes to accommodating various parts in a single bowl, then caps of various sizes are easy to accommodate in a single bowl with simple changeover tooling. For tooling a bowl for caps, three things are required. First being “wiper” which ensures that only a single cap moves forward while the ones on top of each other fall back in as well as those resting on their edge too fall back in. Then comes the “scallop”. It is the part with which the caps with the open side facing ground fall back into the bowl while the ones with the open side facing sky move forward. The third one is the part for ensuring that the caps coming out as “open side facing sky” are turned 180 degrees to make then “open side facing ground”. For accommodating various sizes of caps in a single bowl, the “wiper” needs to be adjusted up or down to ensure that only a single cap moves forward while the one on top of each other fall back as well as those resting on their edge too fall back in. Then the “scallop” needs to be changed as per the diameter of the cap. The third adjustment i.e. that for turning / twisting the caps in 180 degrees, too needs to be changed. However, Elscint has developed an innovative tooling for twisting the caps in 180 degrees that it need not be changed from cap to cap. The same tooling can accommodate a wide variety of caps. However, in case there is a huge variation in the diameters of the caps, then a slight adjustment is required. Elscint can accommodate caps having diameter from 15 mm to even upto dia 100 mm in the same bowl with this innovative tooling.

Most bowl manufacturers mount bowls on a single central screw. This is easy and good as far as removal and re-mounting is concerned. However, it results in a lot of problems with regard to the day to day operations. Due to a single screw fixing there is a tendency for the bowl to shift/rotate  due to heavy vibrations (mainly in the case of big  model bowls ). The shifting can be as much as 10 to 15 mm and can result in a mismatch between the bowl and the linear track or gravity chute. Secondly, due to a single screw fixing the vibrations are not transferred properly onto the bowl from the vibrator. Last but not the least, as there is a lot of pressure on a single screw, it has a tendency to break and the threading can slip. All this can result in the vibratory bowl feeder giving a lot of problems. As against this, Elscint provides mounting on 8 to 12 screws. Due to this, the chance of the bowl shifting does not even  remotely arise. Secondly, as the mounting are on PCD towards the periphery of the bowl, the vibrations are transferred properly and this results in a better movement of the parts on all sides of the bowl feeder. Some manufacturers also provide mounting on the sides of the bowl but this too has its limitations.

There are two places where coils of a vibratory bowl feeder are mounted. One is centrally (either one coil or else two coils) or else on the periphery of the vibratory bowl feeder (three or four coils). Most manufacturers mount the coils centrally. 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. But the disadvantage is that having a single central coil, leads to excessive vibrations at the centre, which reduce as the part moves away from the bowl centre. Whereas some manufacturers like Elscint mount the coils on the periphery of the vibratory bowl feeder. 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.

Usually vibratory bowl feeders are mounted on rubber grommets or anti-vibration pads. These have female threading at the bottom. If one wants to mount the vibratory bowl feeder on a plate, then you need to screw them from the bottom. This increases work. Secondly, being mounted directly on the rubber grommets or anti-vibration pads, the rubbers grommets have a tendency to shear over time or due to any extra pressure. Plus as they are unprotected, oil / coolant etc. can further damage the same. Elscint provides an extra mounting plate for the vibratory bowl feeder below the rubber grommets / anti-vibration pads. This helps in making mounting of the vibratory bowl feeders on plates or stands very easy but also protects the rubber grommets from coolant / oil and other residue which can reduce their life. This extra base plate is below the rubber grommets and is non-vibrating. Furthermore, the cover or the guard of the vibratory bowl feeder is affixed to this base plate and hence it does not vibrate, further reducing the noise of the vibratory bowl feeder.

Flat leaf springs used in vibratory feeders are subject to very high bending forces in a single plane. They must withstand high fatigue conditions as they are expected to deflect many millions of times during their lifetime. Springs of vibratory feeders deflect more than five million times a day in certain cases. Due to this, they need to be made of the correct material as should have high fatigue strength. The speed and performance of a vibratory feeder in many cases depends upon its springs. They need to have the correct length and width as well as thickness. In case the length is more, the chances of breakage increase. In case the width is more, the performance is affected, while in case of lesser width, the chances of breakage increase manifold. Similarly, in case of very less thickness, the springs break a lot while higher thickness will result in lesser vibrations and lesser speed for the vibratory feeders. Usually, leaf springs of vibrators are made of either spring steel or fibre or composite material. There are various advantages and disadvantages of using either of these. The properties of Spring Steel and Composite Springs are given in the following table-

Property                                                                                            Spring Steel             Composite / Fibre                    Units

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Flexural Strength                                                                               932                                760                                     MPa

Flexural Modulus                                                                                28                                  22                                     GPa

Tensile Strength                                                                                 800                                480                                    MPa

Tensile Modulus                                                                                  33                                  23                                     GPa

Compresive Strength at 0 degree                                                      724                               690                                    MPa

Compresive Strength at 90 degrees                                                  315                               690                                    MPa

Maximum stress for infinite fatigue life                                            138                               100                                    MPa

Thermal Conductivity                                                                       0.34                              0.34                                   W/M K

In this table, it is assumed that the correct type of processes have been undertaken on spring steel. As can be seen, spring steel springs are more effective in all respects vis a vis composite or fibre springs. Price of spring steel springs is almost 20% of that of composite springs. Additionally, one needs double the total thickness of composite springs as compared to spring steel springs, further increasing the cost.

If the spring steel springs are so effective, then why do some manufacturers still use composite springs? This is a good question. The answer is that in case of half wave bowl feeders, spring steel springs are of lesser thickness and that too only a few are required. This increases the stress on the springs and they break quite often (even once a day!). Hence, in such cases, composite springs are used in order to increase the thickness and reduce breakage. Secondly, in case of full wave bowl feeders, the springs are in a bunch and the stress on them is very less. This reduces their chances of breakage. Hence, to sum up, springs steel springs are the best for vibratory feeders.