Dearborn Mid-West Company

Automated Electrified Monorails


Overview

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An Automated Electrified Monorail (AEM) is an overhead conveyor monorail system in which each carrier is equipped with its own electric drive and controls, making it self-powered and propelled. Conductor bars mounted on the track supply electric power to the individual carrier's motors, as well as control and communication data to its control panel.

DMW's AEM track is made of extruded high strength aluminum. Aluminum is clean, light weight, and dimensionally accurate. Precision drilling and cutting are made easier, with the use of aluminum.

DMW's AEM systems have the ability to operate at a wide range of speeds from slow to very fast, and they can precisely control acceleration, deceleration, and braking. The AEM's greater flexibility of speed and controls bring performance advantages to transport applications and to assembly operations. AEMs also perform well in buffer and storage applications.

180 mm AEM – Sheet Metal Parts Delivery Conveyor


AEM Selection

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With its self-powered carriers and integrated computer control systems, the AEM offers a degree of flexibility that other fixed-track material handling systems have difficulty matching. For example, sliding or rotating switches allow carriers to transfer horizontally from one track to another, or from one process to another. Vertical drop and lift stations, which take up very little room, permit AEM carriers to move vertically. Unassisted and assisted incline and decline track sections let the carriers make more gradual (and less expensive) changes in elevation. Inclines and declines provide a steady flow of carriers, rather than the individual cycling of vertical lifts. Either method may be used. The selection decision should be based on layout, throughput, and cost requirements.

The AEM has few process limitations, and it offers a highly flexible material handling solution for the right applications. On any technological spectrum showing the full range of different overhead handling systems, the AEM would be labeled the most sophisticated. AEM systems rely on sophisticated control logic and software.

Due to the AEM's high speed capabilities and flexibility, it is compatible with a variety of manufacturing and assembly processes. The ability to run at high speeds can be a great advantage when cycle times are critical. Moving in and out of production cells is accomplished quickly and quietly with an AEM.

Sortation, scheduling, and broadcasting requirements lend themselves well to the AEM because of its high speed and ability to switch tracks. When production operations require longer dwell times for a carrier at a critical machine interface point, an AEM can accommodate that need. An AEM carrier can enter and exit stop stations at higher speeds when necessary to help ease machine cycle time requirements.

AEMs are used in a broad range of industries, both in North America and overseas. They do have some application limitations, based mostly on the workplace environment. Applications such as paint booths, ovens, wash booths, and water tests all require special considerations.

240 mm AEM – General Assembly Production Conveyor


Manufacturing and Production Flexibility

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AEM systems make good use of available building space. As with other overhead handling systems, an AEM requires very little floor space. With the use of sloped track and vertical lifts, the AEM path can be laid out on multiple levels. As production layouts change, the AEM path can change as well. Switches, tracks, and carriers can be easily added or removed. Similarly, additional carriers can be added to provide greater throughput.

One of the goals of flexible assembly is to allow time for a job to be done right the first time, or at least to have the part correctly repaired and ready to go to the next step before it is released. In addition, stationary workstations give workers a better chance to perform tasks correctly. Inventory and work-in-process control are simplified due, in part, to the flexibility of the AEM. Because each carrier can be outfitted with its own identification, such as a bar code label, the carrier can carry vital process and product information specific to that carrier. This data can be tracked by a programmable logic controller (PLC).

Seat System


Reliability and Maintainability

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On average, an AEM system requires less mechanical maintenance than a conventional overhead chain conveyor. In comparison to a chain conveyor, an AEM requires minimal lubrication other than for trolley wheels and possibly the drive motor. However, as with all automated systems, a far greater level of expertise in electronics is needed by maintenance technicians. One important aspect of AEM maintenance is the regular inspection of the carriers. A typical AEM system may have over 100 carriers, their motors, and other electronics. Repair spurs offer the best means for inspecting and servicing the carriers. Because AEMs are designed to communicate with PLCs, carrier diagnostics can be a part of the maintenance program. The PLC can isolate problems with a specific carrier and thereby minimize downtime. Track switches and vertical lifts also should be part of a regularly scheduled maintenance inspection program.

Many AEM production systems with 60 carriers or more have automatic checking stations that check for braking, collector shoe wear, slow-down controls, and proximity sensing.

The performance history of the AEM in North America shows that these systems have accumulated good records of reliability, like those in Europe, which have been in use for over 25 years. AEM system downtime has typically not been a limiting factor to overall production. A fairly simple AEM can operate for long periods with minimal attention. However, a full-time technician with sufficient skills would be needed to monitor a large, complex AEM systems.

Seat System


Protecting Product Quality

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DMW's AEM protects the quality of a part that it is handling and can go a long way toward preventing product damage through the smooth operation of the AEM during acceleration, deceleration, and vertical transfer. Because the AEM is virtually dirt-free, it is an excellent choice in final trim operations where preserving paint finish is extremely important.


Operator Safety Issues

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DMW's AEMs help to create a positive, user-friendly work environment. They integrate well with ergonomically-designed workstations and give employees 360° access to parts. In comparison to most overhead chain conveyors, the AEM is virtually silent, which can enhance the working environment.

As with other types of powered industrial equipment, the AEMs depend on electrical power where every precaution is taken to minimizw safety risks. Covered bus bars and low-voltage power systems are ways of protecting production workers. Proper training of all production workers, supervisors, and maintenance staff that work with AEMs is vital.


Equipment Cost Considerations

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Costs incurred for an AEM system are directly related to what the system is asked to do. In general, the more flexibility that is required, the greater the cost. A system that requires accumulation and sortation capabilities will cost more than one that just requires quick transport from one work area to the next. The main reason is the relatively high per-carrier cost when compared with either OHPF systems or overhead trolley conveyors.

The benefits of increased throughput and the lower cost of production labor need to be analyzed and weighed against the cost of the system. Higher training costs should be factored in as well.


Types of AEM Conveyors

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180 mm AEM:

DMW's 180 mm AEM system can carry loads up to 2400 lbs. (1090 kg), using tandem trolleys on monoplane systems. The load capacity of the system is dependent on speeds, angles of inclines, and the number of tractors used.

240 mm AEM:

DMW's 240 mm AEM system can carry loads up to 15,650 lbs. (7114 kg), using tandem trolleys on monoplane systems. As with the 180 mm system, the load capacity of the system is dependent on speeds, angles of inclines, and the number of tractors used.