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23 August, 2009

Vibratory bowl feeder terminology

  1. Untooled Bowl – A untooled bowl consists of a vertical band and a domed bottom with either an external helical track or an internal helical track. The internal track can also be inverted. It means a basic bowl which has not been tooled (adapted for the parts / components to be fed & oriented).
  2. Tooled Bowl – It means a basic bowl after tooling it (adapted for the parts / components to be fed & oriented). The tooling is custom designed for a particular component orientation & feed rate / speed.
  3. Orientation – The correct position of the part / component at the discharge chute as required by the assembly or placing operation.
  4. Feed rate – The number of parts discharged per minute or hour, as needed to maintain production requirements.
  5. Internal Tooling – Tooling / structure / plates / wipers etc. attached in the bowl for orienting the part in the required manner.
  6. External tooling – The structure / tooling / plates etc. attached to the outer band for the purpose of recirculating parts, to the inside of the bowl, that have been rejected by the orienting and selection devices.
  7. Final Selector – A tooled section designed specifically to segregate only those parts that are in the correct attitude.
  8. Air Jet – A small diameter tube mounted in place which is sometimes used to assist part movement. It is adjusted in the process of development to assist in orientation or final selection with the minimum amount of air pressure.
  9. Slot – An area with a stationary or adjustable gap which orients parts (bolts, screws, etc.) to a “hanging orientation”.
  10. Pre-orientor – Tooling to change the orientatino of a part to the proper position for final selection. A pre-orientor will generate higher feed rates and minimize recirculation of the parts, thus extending the life of the bowl, especially with regard to metal or abrasive parts.
  11. Back pressure Relief – An area of the bowl tooling just prior to the entrance to confinement where the parts will buckle if the discharge is full and recirculate in the bowl. This relieves part pressure which would otherwise cause jamming conditions or misoriented parts to bridge across the bowl tooling.
  12. Full Track Sensor / Auto-Switch Off Mechanism – A means of providing a pressure relief when the parts will not efficiently bubble-off of their own accord. This device can be either a proximity, fiber optic, or pneumatic type sensor to signal the feeder to start or stop. Also a sensor can activate an air jet to eject excess parts from the entrance to confinement, in which case the ‘bowl would continue to run (this is mostly used with multiple track bowls).
  13. Discharge Chute – A short section of track that is mounted to the bowl. The discharge chute controls parts in the orientation, achieved in the bowl and in most cases, conveys them to either to a horizontal vibratory straight line linear track or a gravity track.
  14. Confinement – A containing section used to control parts through the discharge chute. Confinements are designed in a manner to allow access to the parts by removal of “bolt-on” sections in most cases.
  15. Dust Hole – A dust hole is used to discharge small particles of foreign material from the bowl without interfering with flow of the piece parts.
  16. Quick Dump Chute – A quick-opening “window” that is provided to facilitate changing from one part to another when multiple styles or sizes of parts are being fed from the same bowl.
  17. Counter weight / balance – A solid steel block of predetermined size and weight that is added to the exterior of the bowl. The location is determined on a counter-balance wheel, in order to offset the weight of the external tooling, etc. (static balance).
  18. Storage Hopper – 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.
  19. Silo – A storage hopper mounted above the bowl which is used to hold extra parts for replenishing the supply in the bowl. The parts move down from the silo as and when they find place. The silo design is made in such a way that the weight of the parts kept in the silo does not come on the bowl / vibrator.
  20. Gravity Track – Gravity tracks are methods of conveying parts. This type track must be set on an angle great enough that gravity will convey the parts from the discharge chute of the feeding system.
  21. Magazine – This is also a method of conveying parts. A magazine is a track in which oriented parts are stacked.
  22. Escapement / Singulator – A pnuematic device placed at the end of the feeder discharge, horizontal straight line or gravity track to isolate the end part.
  23. Drive Unit / Driver / Base Unit – The force used to power the drive unit is accomplished by using one or more electromagnetic coils which act upon pole face plates to generate vibratory motion. The upper and lower members of the drive unit are constrained by leaf springs causing torsional vibration which is transferred to the top member in the form of feed motion. When the drive unit moves the parts at maximum efficiency with minimum current effort, the unit is said to be tuned to a natural frequency of the power source. The mass and diameter of the feeder bowl is the determining factor in tuning the unit. As this mass or diameter is increased, more leaf springs must be added. The rubber feet of the base drive play an important part in allowing the lower member of the drive unit to act as a pendulum to power the bowl.
  24. Coil Noise – A warning sound which indicates that the coil gap is set too close, causing the pole faces to strike. This condition will result in damage to the drive unit if not corrected.
  25. Tuning – Proper tuning is an important factor in achieving maximum speed. When a drive unit is improperly tuned (over or under-sprung) the spring tension does not correspond with the natural frequency of the feeder mass. Either condition prevents the mass from returning to its neutral position before the next magnetic pulse takes over thus restricting the full motion each 1/2 a second. Normal 50 Hz current produces 100 magnetic cycles per second, and transmits 100 mechanical cycles per second to the bowl. Tuning the unit to a natural frequency of either 50 Hz or 100 Hz, for proper balance between coil assembly energy development and spring tension, is of utmost importance to a smooth and efficient feed system. At this balance point it should be noted that parts will feed at maximum efficiency with minimum current draw. The addition or removal of springs may be necessary to obtain the balance needed. The same principles apply for 50 Hz except one half of the magnetic pulse is cut out, leaving only 50 mechanical movements per second (sometimes referred to as 1/2 wave or rectified current). The air gap between the coil assembly and armature plate is important. If the air gap needs to be reset, adjust it so the pole faces are as close as possible without striking. This will generate maximum power with minimum amperage draw. If the air gap is too small, the coil will clatter; if too large, the energy will not be used efficiently, causing the coil to overheat.
  26. Linear Vibrators / Straight Line Drive Units / Vibratory Tracks – Linear vibrators / straight line drive unit is designed to produce linear vibratory motion. It is used to power tracks that convey parts horizontally from the feeder bowl discharge to a dead nest or mechanism. It operates on same principles of Base Drive Unit.
  27. Isolation Springs – The lower spring packs that act to absorb vibratory motion and transmit it to the body of the straight line drive unit.
  28. Shims – The small parts placed between two springs.
  29. Rubber Grommets – Anti-vibration mounts kept to ensure that the vibrations of the vibratory feeder are not transfered to the bottom base plate.
  30. Coating / Lining – Coating of polyurethane either spray coated or pasted to ensure that the life of the bowl increases and extra friction is created.
  31. Oil Drain – A hole with a plug to ensure that excess oil accumulated in the bowl over time is drained out.
Monish Shet

Monish Shete is CEO of Elscint Automation, a 30 year old firm manufacturing vibratory bowl feeders and similar small part handing products. He personally has more than 25 years experience with last 15 years being with Elscint. This blog will help customers and laymen understand the intricacies of vibratory bowl feeders. One can find information about the finer aspects of vibratory bowl feeders which cannot be found anywhere else. Case studies and information about various innovative ways of feeding and orienting of different parts are given in this blog.


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