Bowl Feeders

Chapter One – What is a Bowl Feeder?

A bowl feeder is a vibratory instrument for supplying predominantly small parts and components to a production line for automation, or for sorting bulk items for rapid use. Vibratory bowl feeders are a robust and reliable solution for handling and sorting bulk materials and orienting them correctly for assembly purposes.

A self-contained bowl feeder system has a bowl that sits on a spring-loaded base that moves vertically. Small parts and components move up the bowl tooling via vibration. Bowl feeders can be a fairly flexible form of parts feeding to handle very small parts such as a pill or components that can be as large as six cubic inches (15 cm^3).

Although bowl feeders take up very little space, they are capable of arranging, selecting, feeding, and sorting parts in a very cost effective way. The effectiveness of a bowl feeder is measured by its output rate, part orientation, and the space it fills on the production floor. Bowl feeders can have an output rate as high as 1600 parts per minute.

Chapter Two – How Bowl Feeders Are Used?

Since bowl feeders are used to organize and singulate bulk samples of parts, they are essential in automation and material handling processes as an efficient and reliable method for enhancing manufacturing and assisting in the use of labor. Bowl feeders are used in automotive production, chemical processing, electronics manufacturing, food and beverage processing, foundry work, glass making, mining, packaging, pharmaceuticals, railroading, and recycling.

When a bowl tooler produces the bowl for a bowl feeder, they tool it such that the parts are guided along the circumference of the bowl on the inside and outside of the bowl. The length, shape, and size of the track are chosen to meet the required criteria for feeding the part, including orientation and direction. In some cases, a special coating is required to assist in the feeding process.

Uses for Bowl Feeders:

Feeding and Positioning Parts:

Bowl feeders can be designed with a simple plain feed or tooled and engineered for special part orientation, position, and selection. These factors are controlled by a variable speed controller with an electrical supply.

Automating Manual Labor:

Bowl feeders are a cost effective method for replacing manual labor. They are used for automatic feeding of parts to an assembly workstation and positioning of high-volume parts. The feeder is placed under a hopper that provides a continuous flow of material.

Counting Out Precise Parts:

A counting bowl feeder counts an exact number of parts to be placed in a process or for packaging. Single parts or several parts can be counted and matched using one or several bowl feeders. A counting feeder is customized according to the size and number of objects

A count and batch conveyor counts parts using the pre-programmed system and selects the proper number of parts at its exit. Essential to the system is programmable counting electronics for setting the required quantities. Additionally, the counting system is designed to reject and remove undesirable parts using selector blades.

Moving Parts With Pick and Place:

In pick and place, parts are directed to the work station in the correct position using a linear inline feeder to be securely assembled, They are used in situations where sending a part down a feed hose or tube will not place the part correctly, such as orienting a screw for placement.

The linear inline feeder is the final step in the feeding mechanism. It orients parts such that they are ready to be added to the operation. The pick and place process serves as the final screening since it forces parts to be oriented correctly. Ones that are misaligned fall out and return to the bowl feeder.

Inspecting and Detecting Parts:

Vision inspection systems check parts as they leave the bowl feeder. Parts that do not meet specifications programmed into the PLC as rejected and removed from the bowl. A proximity sensor detects an improperly oriented part and removes it from the feeder track. The initial detection of an incorrect part is completed using a camera. The PLC system compares the image from the camera to the programmed image. Any part that does not match is removed.

Chapter Three – How does a Bowl Feeder Work?

The term "bowl feeder" is a general description given to devices that feed parts for multiple and different applications. Basically, a bowl feeder uses mechanical vibrations or centrifugal force to move parts along a conveying track to an assembly, shipping, inspection line, and other operations.

The unique designs of bowl feeders do not make it possible to describe all of the features of every type. There are certain commonalities between bowl feeders, which include the bowl and base plate.

Hoppers in Bowl Feeders:

The hopper is the storage area for parts prior to being sent to the feeder bowl. It eliminates overloading or insufficient quantities in the feeder bowl and can be monitored by a level control switch. Hoppers operate automatically using a signal from the level control switch. The use of hoppers eliminates any chance of an oversupply or deficiency of parts in the bowl.

The three types of hoppers are manufacturing, coating, and controlling

• Manufacturing Hoppers - Manufacturing hoppers are known as stock hoppers and can be top types or flat types. Flat types are more popular since they do not increase the loading height.
• Coating - Coated hoppers are helpful when metal parts are being fed into the bowl since they reduce the amount of noise created in the feeding process
• Controlling - Every hopper has a controller for controlling and varying the speed of the hopper. A level controller monitors the component level using a level sensor, which controls the start and stop of the hopper. A controller is necessary to ensure the proper quantity of parts is always in the bowl.

Feeder Bowl Diameter:

The diameter of a bowl feeder is the central element of the process. Its design has to fit the type of material that it will convey. A crucial factor in the design of a bowl feeder is the diameter of the feeder bowl, which should be ten times the length of the part to be fed. In correct feeding, parts make contact with the bowl track.

If the bowl diameter is too large, the bowl will not work. Parts will jump, and orientation and proper feeding will not take place. If the diameter of the bowl is too small, the base unit will protrude, and the drive unit will be of too high a capacity.

Correct bowl diameter is essential, especially when part orientation and a high speed rate are important. This aspect of the bowl feeder selection process requires an experienced engineer and manufacturer to assist in the selection and design process.

Base Unit:

The base unit is the drive unit for the feeder system. It is selected according to the materials that will be fed, which includes their size, weight, length, and the number of parts that will be in the bowl. The base unit is supported by three or four leaf springs, which ensure that the bowl only moves in a vertical direction. Under the feeder base are one to six electromagnets that create magnetic vibrations that are converted into mechanical vibrations.

Square base bowl feeders need a large reaction mass to operate and create a great deal of vibration. Round bases have less mass reaction and vibrate less. Additionally, a common base for multiple feeders generates cross talk, which can enhance or reduce feeder operation as the group of feeders’ wave forms add to or subtract from each other.

Linear Feeder:

Linear feeders accumulate and orient parts from the feeder bowl to be moved to assembly or other machines. The four types of linear feeders are vibratory, conveyor, airveyor, and gravity. Except for conveyor linear feed systems, all linear feeders increase the amount of noise created by feeder bowls but are a necessity for proper pick placement.

• Vibratory Inline Feeder Systems - Vibratory inline feeder systems are paired with vibratory feeders to move parts from the bowl to the pick point while maintaining part orientation. They are ideal for small parts, durable, and are low friction. Vibratory inline feeder systems are six inches long (15 cm) or longer. Aside from their basic design, they come with different special features such as controllers and extended drive bars.
• Conveyor Linear Feeder Systems - Conveyor linear feeder systems are normally paired with centrifugal bowl feeders. They are capable of high accumulation and operate quietly at high speeds. Conveyor linear feeder systems normally have a control system that increases their efficiency.
• Airveyor Inline Feeder Systems - Airveyor inline feeder systems are an ideal solution when elevation change is required. They work at very high speeds but are gentle on parts. Airveyor inline feeder systems use blowers to move parts and are the perfect solution for rapidly moving lightweight parts. The one stipulation for the use of an airveyor inline feeder system is that the parts to be conveyed have a shape where air causes drag on them.
• Gravity Track Linear Feeder Systems - The force that guides a gravity track linear feeder system is gravity without any form of mechanical energy. They are the least expensive of the linear feeding systems, produce less noise, and do not require any form of consumable parts or maintenance. Gravity track linear feeder systems have to be located at a higher elevation for the downward angle track to be effective.

Feed Rate:

The feed rate is the number of parts that will be moved over a set period of time; it is expressed in parts per minute. It depends on the configuration of the parts, the need for positioning, how many tracks there are, and the size of the unit. An important step in determining the feed rate is a thorough examination of the part being fed. There are six basic factors that have to be examined to determine the feed rate.

• Part characteristics - Part characteristics include their dimensions and make up.
• Composition - Composition refers to the materials or metals used to produce the part, which determine wear characteristics and friction coefficient.
• Orientation - Understanding the necessary orientation of a part is an essential part of bowl feeders' function. Knowing how a part should be positioned when it is being fed to the pick point is very important and strongly influences the feed rate.
• Weight - The weight and center of gravity of a part will influence its orientation and will have an impact on the feeding system.
• Process - All bowl feeders are part of a larger system and must be able to be integrated easily into the existing system. Being aware of the characteristics of a system makes the insertion of a bowl feeder easier.
• Part Condition - A major factor in the determination of feed rate is whether a part is oily, wet, or moldy. Each of these conditions dramatically influences the feed rate. Dry parts are easy to feed, while production parts that have been stamped and lubed require special preparation. Parts that are wet and have been wet lubed tend to stick to the sides of the bowl feeder.

Generally, a large vibratory bowl feeder can move 45 to 50 feet (13.7 to 15.2 m) of parts per minute or 600 inches (1524 cm) per minute. A centrifugal bowl feeder can move 3000 inches (7620 cm) per minute.

Feeder Bowl Level Control:

Feeder bowls will only operate properly if the number of parts in the bowl is the correct amount. Too many parts may damage the parts, while too few parts will slow the process.

Sensors monitor the number of parts in the bowl to ensure that there is the right amount. An essential feature of bowl level control is the addition of a hopper to the feeder system. The hopper should have a level control switch that senses the need for more parts in the bowl and automatically dispenses them. As the feeder bowl empties, the amplitude of its vibrations will increase. Such a condition can lead to reduced feed rates due to too high of an amplitude.

Feeder Track Detection:

Feed track detection is designed to prevent jamming and clogging. Sensors turn off the track if it gets too full. The image below has a sensor at the entrance and discharge of the feeder.

Amplitude Controller:

Base units, inline linear feeders, hoppers, and orienting rolls have to have a method for limiting their vibration speed. Amplitude controllers are necessary for all vibratory systems since the system would otherwise operate at maximum speed, all the time. They are necessary to compensate for changes in feeder cycle rates.

Amplitude controllers have counter electromagnetic field (EMR) and infrared (IR) feedback to stabilize the motor speed of the feeder system. Electronic limiting reduces the motor starting current, which prolongs the life of the motor and semiconductor. The majority of motors for vibratory bowl feeders have direct current (DC).

The amplitude controller monitors the rate of the vibration on a bowl feeder. If a bowl feeder does not have a controller, it will run at its maximum output, which necessitates the use of a variable rate controller to keep vibrations uniform.

Noise Reduction:

Noise in a bowl feeder is caused by the movement of parts in the bowl. It can get so loud that workers have to wear noise-reducing gear, such as decibel-reducing earmuffs. Sound enclosures are used to reduce noise levels created by the bowl feeder process. Additionally, the bowls of bowl feeders are lined with noise suppressing materials, which protect parts and reduce noise.

Chapter Four – Types of Bowl Feeders

Bowl feeders are divided into various parts depending on how they move, their material and their design. Though all types have a bowl, the way the parts are manipulated varies depending on the existing process, rate requirements, orientation requirements, and part material.

Vibratory:

Vibratory bowl feeders are the most common style and are most readily found when searching the internet. They use a vibratory drive unit to move parts through the bowl. Vibratory bowl feeders are like a workhorse and seldom need maintenance if properly maintained. In cases where a vibratory bowl feeder is moving oily, greasy, or dirty parts, it may need to be regularly cleaned.

Centrifugal:

Centrifugal bowl feeders, common referred to as rotary bowl feeders, are more complex than vibratory bowl feeders. They use a bowl that spins and forces parts to the outside of the bowl. Centrifugal bowl feeders are ideal for high-rate applications that do not require part orientation or manipulation. The common style of centrifugal bowl feeders has a center disc and outer tube that spin at different speeds. Parts inside the bowl are moved in a circular direction by centrifugal force that pushes them to the edge of a conical-shaped disk inside the bowl.

The system of a centrifugal bowl feeder is capable of moving 1000 parts per minute and operating silently without vibrations. They are ideal for fragile, small parts made of plastic, rubber, or metal.

Conical:

Conical bowl feeders, or cascade bowl feeders, are a type of vibratory bowl feeder with a cone shaped bowl. Parts are positioned on the inside wall to reduce part circulation and abrasion to assist or when a specific angle required to feed the pan. The process is used for parts with simple geometries. They have an open cavity design for use in clean rooms, the pharmaceutical industry, and food processing.

Custom Bowl Feeders:

The majority of bowl feeders can easily fit into any production or assembly operation. It is one of the reasons that bowl feeders have become such a vital part of manufacturing. The adaptability of bowl feeders to be inserted into part allocation systems improves efficiency and cost effectiveness.

The generic nature of bowl feeders broadens their application but does not make them inclusive for all types of production. The challenge of designing a feeding system for unusual and unique conditions is what bowl feeder manufacturers use to improve their perspective and customer service. Each detail of a process is studied and examined such that the design of the feeding system exactly fits the assembly process, smoothly and effectively.

Chapter Five – Types of Bowls for a Bowl Feeder

The central feature of a bowl feeder is its bowl, which can come in varying sizes and shapes. The most common bowl designs are cylindrical, conical, stepped, and polyamide.

The diameter of the bowl is a crucial feature of a bowl feeder and determines the size, shape, and type of parts that the feeder can handle.

Cylindrical:

Cylindrical bowls are used for most part feeder applications due to their low cost of construction and tooling. Also referred to as outer pan bowls, the orientation of parts is done on the outside track, which is pitched downward to improve separation and orientation. Cylindrical bowls are widely used for small parts because of their restrictive capacity.

Conical:

Conical bowls have a higher capacity with a diameter that helps in pre-separation. They can have an increased number of tracks and track widths.

Outside Track:

Outside track bowls are used for operations where exact part orientation is required and a higher feed rate with multiple lines. The track is angled downward for parts to separate more quickly. When parts buckle, they fall into the inside bowl.

Stepped:

The feeding track on a stepped bowl is wider, making it ideal for pre-oriented parts. It has a larger bowl that prevents parts from getting jammed.

Polyamide:

Polyamide bowls are made of plastic, which allows parts to slide more easily and avoids the issues of steel on steel. The properties of plastic allow for greater flexibility in the shaping of the bowl and increased noise reduction.

Bowl Materials:

Bowls are typically made from cast aluminum, plastic, certain grades of steel, and stainless steel.

Track Configurations

High Negative:

Negative tracks have a negative angle for flat nonuniform parts.

Positive:

Positive tracks are at an angle that is less than 90o between the track and wall.

Multiple:

Multiple track bowls have several tracks along the side of the bowl.

Radius:

Radius form tracks have a groove and are used for cylindrical parts.

V-Shaped:

V-shaped tracks have a groove of varying angles depending on the requirements of the part.

Negative:

In negative tracks, the distance between the wall and track is larger than 90o and is used for caps and rectangular stamped parts.

Chapter Six – Industries that Use Bowl Feeders

Bowl feeders have become an essential automation device for many industries rely on bowl feeders for speeding up productivity and assembly. The number of production processes that use bowl feeders is wide and varied. Their easy use and lack of maintenance have made them an ideal choice in helping speed up production.

Automotive Industry:

The speed of automotive production requires parts to be fed with the proper orientation and for feeders to be able to handle a wide variety of sizes and shapes. Cascade bowl feeders are used to supply small components, such as screws, bolts, and dowels. Large parts are fed using an outside track bowl feeder, as seen in the image below.

Electronics Industry:

The electronics industry uses bowl feeders for sorting and positioning electrical components, such as pins, tubes, and fasteners.

Pharmaceutical Industry:

One of the specifications for the pharmaceutical industry is cleanliness. Bowl feeders have to be able to move materials without any concern for contaminates, so they are designed to exacting specifications, which include special metals. An important qualification is their ability to meet Food and Drug Administration guidelines. To meet cleanliness requirements, bowl feeders for the pharmaceutical industry are made using stainless steel grades 304 and 316L.

Ordnance:

Bowl feeders can be engineered and designed to handle explosive materials.

Food Production:

The food production industry is constantly looking for methods to improve productivity. Bowl feeders have become an integral part of the industry‘s changes. The biggest problem, with food production is the stringent regulations regarding contaminants and sanitary conditions. Food bowl feeders can move 500 pieces per minute at sizes ranging from 30 to 50 inches (76.2 to 127 cm).

Packaging:

The consumer packing industry is ever-changing as new lids in various shapes and sizes are produced. Engineering feeders to meet the ever-developing demand is a challenge for the bowl feeder industry. Systems need to be easy to change and adjust.

Cosmetics:

An essential part of the cosmetics industry is the appearance of the container. Feeder systems for cosmetics have to be efficient to avoid part recirculation and avoid irregularities. Parts have to be in perfect condition after going through the bowl feeder process.

Conclusion

• A bowl feeder is a mechanism for supplying small parts and components to a production line or for sorting bulk items for rapid use.
• A bowl feeder uses mechanical vibrations and centrifugal force to move parts along a conveying track to an assembly, shipping, inspection line, and other operations.
• There are a vast number of industries that use bowl feeders as a method of automation.
• Bowl feeders are divided according to their method of moving materials.
• The central feature of a bowl feeder is its bowl, which can come in varying sizes and shapes.