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.

A storage hopper is used to hold extra parts for replenishing the supply in the bowl. Hoppers are 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.

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.

Vibratory Hoppers or Stock Hoppers can be of various sizes and dimensions and types like the top type and flat type. Amongst vibratory hoppers, the flat design is most popular. This has the added advantage of not increasing the loading height of the hopper too much and secondly increasing the loading capacity without compromising on the space required.

These types of hoppers can be provided either in Stainless Steel or Mild Steel. In case of mild steel, it is preferable to use a coating or lining like the Elscinthane PU coating from the inside. Coating is also required in case of metallic components when can otherwise make a lot of noise in the hopper.

For each hopper a vibratory controller / regulator is required for controlling / varying the speed of the hopper. Additionally a level controller for controlling the component level has to be provided. This is controlled by a level sensor mounted on the hopper itself. This provides a start / stop operation, thus resulting in increased efficiency of the downstream equipment like vibratory bowl feeders as well as centrifugal / rotary feeders.

            Hoppers ensure that the quantity of components loaded in the bowl always remains the same (with the help of the start stop function of the level controller) and hence can help in achieving better functioning and working of the bowl feeders.

Vibratory bowl feeders are the best feeding devices for automating the operation of centreless grinding machines, mainly the through feed types of centreless grinding machines. The vibratory bowl feeder is used for orienting the component in the correct manner / orientation, which usually is axial orientation.

After the component is oriented in the correct manner, it has to be further transported onto the work rest of the grinding machine. There are three possibilities for making this transfer-  

1. Gravity Chute – In case of the gravity chute, the back pressure of the components and the inclination of the chute result in movement of the components from the bowl to the work rest of the centreless grinding machine. The advantage of using a gravity chute is that it is cheaper to make as well as to maintain. But the disadvantage of the same is that due to the emphasis on back pressure and inclination, a few (7 to 8) components are always required in the chute for generating continous and consistent pressure for the grinding operation. This always may not be possible and can lead to uneven pressure and quality of the ground components suffer due to this.
2. Small Parts Conveyor Feeder – This is a conveyor kept ahead of the bowl feeder for conveying the components onto the work rest of the grinding machine. It can generate consistent and continous pressure on the components and works very well with excellent results. The disadvantage is the cost factor, which is high and additionally, for better results, a variable drive is required, which further adds to the cost of the conveyor. Add to this the usual maintenance costs associated with the geared motors, belts etc. and this does not become a cost effective solution.
3. Linear Track – A Linear track is a chute mounted on a linear vibrator which can do the work of conveying the components from the bowl to the grinding machine work rest. The linear track can generate the same 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.

Therefore, the best way for feeding of components to a centreless grinding machine is to provide for a linear track ahead of the bowl feeder. This is the best and cost effective solution for automating of a throughfeed centreless grinding machine.

While buying a vibratory bowl feeder, one requires to purchase some accessories along with the same. If the right type of accessories are purchased along with the vibratory bowl feeder, then integration with your machine becomes easy. Otherwise, one has to manufacture such accessories after the vibratory part feeder arrives and thus a lot of time is lost in the same. Secondly, as vibratory bowl feeder manufacturers keep a lot of accessories in stock, it helps to order these items from them so that integration issues are negligible. The various accessories which go along with a vibratory bowl feeder are listed down –

1. Coating / lining – These can be 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. 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, these results in the components slipping and hence they are not able to feed properly. Proper type of coating can eliminate this.
2. Stand – These can be cubical, single post, special, made of aluminum extruded sections etc. It always helps to purchase stands from the bowl feeder manufacturer so that further work at the customer’s end is eliminated
3. X-Y Tables – These are required for small adjustments on X and Y axis.
4. Portable Jacks – These are used for Z adjustments in case of smaller vibratory feeders where small amount of height adjustment is required
5. Hoppers – These are used for providing extra loading capacity. This way, one can purchase a smaller sized bowl feeder and have extra loading capacity by way of the hopper.
6. Silo – These are again used for extra loading capacity. These help increase the loading capacity of the bowl at a very low cost.
7. Noise Suppressors / Enclosures – These can be either of acrylic or mild steel lined with acoustic foam. These can help in reducing the noise levels drastically. This is especially useful in case of bigger bowls with heavy metallic components.
8. Gravity Chutes – These are gravity tracks made to move the components further from the bowl.
9. Linear Tracks – These are vibrating tracks which are used for moving the components further from the bowl.
10. Non-vibrating part – These are used to provide a nesting point for pick up ahead of the vibrating linear tracks.
11. Auto-Switch Off mechanism – This is switch on / switch off of the vibratory bowl feeder based on whether components are present in the linear track or gravity chute as the case may be. This can ensure that the vibratory bowl feeder does not remain working when the output is not being used. It can also save on energy costs.
12. Level Controller – This is useful in case a hopper is used along with the bowl feeder. This can help to start / stop the hopper once the level of components in the bowl feeder goes below a particular level.
13. Elevators – Similar to hoppers, these can enhance the loading capacity.
14. Escapement / Singulator – These are used for ensuring that a single component comes forward while the rest are held back. This is useful when only one component is to be used at a time.
15. Counter – This along with a sensor is used for counting the number of components being fed through the vibratory feeder.

 As can be seen, there are a lot of accessories which one can order along with a vibratory bowl feeder to ensure that it becomes a plug and play equipment. It is also better to ensure that one purchases vibratory bowl feeder from a manufacturer who offers all of these accessories under one roof and keeps most of them in ready stock so that delivery time is compressed.