power and free conveyor

Power & Free conveyors have been among the most versatile and productive conveyor systems available. Modern advancements in control and automation devices have greatly added to the contributions that this style of conveyor can make in the areas of just-in-time (JIT) delivery, flexible manufacturing and other advanced manufacturing methods.

A power-and-free system utilizes a free rail and multiple drive rails to transport parts through the various stages of the process at different speeds. The drive rail, which has a chain and drive like the continuous speed conveyor systems, sits above the free rail. Two load supporting
trolleys/ tracks, connected by a load bar, ride on the free rail below( one above another). Similar to trolley conveyor due to use of discretely spaced carriers transported by an overhead chain; however, the power-and-free conveyor uses two tracks: one powered( conveyor chain) and the other nonpowered (or free)(load carrying trolley) .

Power track chain engages the trolleys and moves the load to a predetermined location. The load can be dropped and picked up by another drive. This gives the power-and-free conveyor the flexibility to move product at different speeds, to stop and accumulate product onload bars, or to route product to different locations.

Termed an Inverted Power-and-Free Conveyor when tracks are located on the floor.

How it works?

Controls for power-and-free systems utilize programmable logic controllers (PLC) for operation. The carriers are fitted with coded identification methods to indicate to the PLC how they are to be routed through the system. A mechanical flag or bar code is used to identify each carrier. The loader inputs the process information related to the carrier. As the carrier approaches a switch point, the flag is read by a photoeye and the PLC determines which way to route the carrier.

The operator may interface with the control system with simple indicating lights or a more sophisticated system like a touch screen or other graphical system.

The controls for any conveyor system should include a simple to understand input process to avoid operator error. Audible alarms should be included to announce a start up of the drive. System status can be monitored and details of daily operation can be stored and retrieved.Careful thought should be given to what control features are needed.

Advantage:

• With a power-and-free system, the two trolleys can be moved onto separate rails to make it possible to reverse the direction of the part without a turn. The flexibility of a power-and-free system can make them a very desirable asset in certain situations.


• Processing, assembly, machining, painting, inspection, load/unload and shipping are but a few of the activities that can be performed all at the same time within the system.


• The system is useful when product mix calls for different procedures to be randomly applied to parts and assemblies. This makes Power & Free systems ideal for JIT and flexible manufacturing systems.


• Through the use of computers and automated readers, it is possible to keep track of the status of all components in the system. This enables engineering and production personnel to manage production more closely.


• Power & Free setups can interface with today's robots, process equipment, and other systems offering greater productivity, flexibility and control.
  
• Power & free conveyors provide the unique ability to stop individual loads without stopping the entire production line. They offer a wide range of features including: variable chain speeds, high-speed indexing, on-line storage, and adaptability to changes in elevation - all designed to maximize your production capacity。

Disadvantage:

However, power-and-free systems are complex designs that must be carefully balanced to avoid problems. They are also very expensive and they require more conscientious maintenance and care in operation.

Power and Free conveyors are well suited for applications such as:

• Paint lines where products need to be routed to multiple spray booths or where accumulation in an oven or elsewhere is advantageous
• "Live" overhead storage of products, where high density is key
• Work in progress
• Assembly lines, where non-synchronous movement is required

Latest trend and types of power and free conveyor:

Like the highly successful ATS Supertrak™, the innovative, new Econotrak™ power & free conveyor offers multi-axis flexibility based on the unique ATS cantilevered pallet design.

A lean version of the highly successful ATS Supertrak™, the innovative, Econotrak™ power & free conveyor from ATS Automation Tooling Systems Inc. Offers many of the same benefits, at lower cost – speed, simplicity, flexibility and long life. Econotrak™ offers performance and cost advantages over conventional belt- and chain-drive conveyors, particularly in high-volume applications such as those in the medical and automotive industries.

Like synchronous belt-drive conveyors, the Econotrak™’s belt moves continuously, driven by a variable-speed AC motor and VFD, but that’s where the similarity ends. Econotrak™’s pallets engage the belt by means of a toothed pulley with an integrated clutch. Tooling on the leading edge of the pallet disengages the clutch when actuated.

Although Econotrak™ is competitive in price with other conveyors, it offers important advantages in speed, productivity and flexibility. Its cantilevered pallet design, allows full multi-sided access to pallets and fixtures, eliminating the need for lift & locates. Multi-axis operations can be performed right on the pallets, saving cycle time.

In addition, because the pallets are not in continuous contact with the belt, there’s less load on the drive motors. This enables Econotrak™ to support more pallets, eliminating the need for multiple conveyor loops. Alternatively, it can reduce the number of drives required. Because wear is not applied to the belt during stops, as with other conveyors, belts and motors last longer. The result is lower maintenance costs. Expanding the system is easy on the budget too, since the system is made from low-cost, industry-standard components.

ATS has long been recognized as an innovation leader in the automation industry. Econotrak™ is a prime example of how ATS is advancing 21st century automation to meet that commitment.

Inverted power and free conveyor:

SSI Flush with Floor Inverted Power & Free Conveyor
moving product through a paint booth

It is designed based on the theory of Power & Free Conveyor, but inverted upside-down. It is a new type of conveyor with high efficiency. Despite all the features of Power & Free Conveyor, it has more features:

1. Work-pieces are on the conveyors and it is impossible for anything to drop from guide-way onto the work-pieces.
2. It can be installed at the same level of the ground, then workers can work very close to work-pieces and improve the work efficiency.
3. If it is cooperated with over-head traveling dryer, a lot of energy can be saved.
4. If it is used in fitting shop, it can be installed under ground to bring convenience, and keep the workshop in a clean position.

The Inverted Power & Free is one of the most popular systems on the market, and has satisfied customers worldwide. It ensures significantly increased operating efficiency and flexibility, making it adaptable to virtually any kind of production line.

It is ideal for production, assembly and finishing operations where workstations must be supplied on a continuous basis, as well as for use in harsh environments such as wash and paint booths, bake ovens, etc. They are designed to accommodate industrial applications, which demand a high degree of versatility and adaptability.

Inverted power and free conveyor systems provides advantages:

• They provide complete accessibility to the product which makes it ideal to use with automation for assembly operations or painting, No bulky carriers are required, resulting in lower costs and less energy to move loads, Systems are clean, as no conveyor debris falls on the product, Systems are generally floor mounted thereby eliminating costly ceiling reinforcement.
• Inverted power and free conveyors can also be mounted in pits and equipped with floor covers and seals to allow traffic across aisles.
• The free trolleys utilize guide wheels on two levels to ensure greater stability.
  Open track construction allows for removal of carriers, trolleys, wheels and chain anywhere in the system.
• The chain is guided through the entire system. Tracks are constructed from standard angle section to allow precise tolerances in a wide variety of materials and sizes.
• Track construction can vary to fit your requirements.