Advantages of Electric Shaker Conveyors and Top Tips

February 26, 2020

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When metal stamping operations run full, everything moves fast. Part throughputs can reach 100 parts/min. or more. After each punch, metal trim falls away through the die, collected as scrap for recycling or sale. But all of that production quickly halts should scrap not clear away.

Efficient, reliable clearing of scrap from metal stamping presses is critical to overall plant productivity and pro???tability. Shaker conveyors provide such capability, but they must be properly designed, engineered, installed and operated to deliver trouble-free performance.

Four Causes of Shaker Failure

Based on the experience of designing, engineering, installing and servicing scrap shaker systems, we have found most failures of shaker conveyors have root causes in four key areas:

Uneven pan loads. Basic physics suggests that uneven pan loads can stress shaker systems designed for more balanced loads. Operators should ensure installation of an equal number of pans with even spacing on each side of a shaker system’s crossbar. If not, the uneven weight load of scrap metal can cause the top plate of the shaker system to twist with each movement. This twisting action places extra stress on the system’s motor and bearings, causing either or both to fail. Some setups may require uneven pan loads. Here, solutions exist. For example, Magnetic Products, Inc. (MPI) has developed a rack-and-pinion (RP) system. This utilizes an RP gear setup at the end of the extrusion to prevent the twisting movement from uneven loads.

Jams. Scrap or parts falling through a die can bounce and end up in various locations around the press, jamming between the shaker-system pans or drive components. When these jams occur, clear them out to prevent excessive wear on the motor and its linear bearings.

Insufficient support and leveling of pans. When installing pans, make sure that they are level with the press bed. Inclining or declining pans can add unwanted torque to the motor, creating excess wear. To better support pans and reduce friction from metal-on-metal contact, use ultra-high-molecular-weight polyethylene pads or lining.

Poor pan installation. Crooked or loose pans, or pans banging against other objects, can create additional operating stresses, leading to premature bearing or motor failures. A solid installation can be achieved in several ways. Quick-release pan-mount brackets such as those offered by MPI offer a solution. These brackets lock down the pan securely while also enabling quick and flexible changes in pan placement. Another tip: Crossbars to which the pans mount should not exceed the manufacturer’s maximum recommended length. Be sure to follow the stated length recommendations.

Advantages of Electric Shaker Conveyors

Properly installed and maintained electric shaker systems eliminate the common causes of operating failures noted above while providing years of trouble-free service. In addition, they also deliver significant performance and cost advantages over their pneumatically driven counterparts. Advantages include the following:

Efficiency. Electric shaker conveyors eliminate disruptions caused by maintenance and repairs frequently required by pneumatic shaker systems, thus providing immediate and significant boosts in shop-floor efficiency. Also eliminated: wasteful leaks in air tubing, which can run thousands of feet, along with the need for air compressors, thus freeing valuable floor space.
Reliability. Given the harsh operating conditions encountered in metal stamping plants, electric shaker conveyors are designed, engineered and built to be extremely reliable. Some systems, including MPI’s M-series models, for example, avoid using seals and damping components that require maintenance and repairs. More-complicated pneumatic models feature more parts and assemblies that can break down. Except for the need to clear infrequent jams, electric shaker systems can provide years of trouble-free service.
Simplicity. Pneumatic systems require compressed air from compressors, often located far from stamping presses. The compressors, tubing and connections required with these shaking systems constitute a complicated infrastructure that requires lubrication, plus periodic and as-needed maintenance and repair. Electric shaker systems operate virtually maintenance-free with much longer service intervals and fewer required spare parts.
Energy savings. Electric shaker systems use 71 percent less energy as compared with 3.4-ft.3/min. pneumatic setups. Given the number of stamping presses in a plant and how long they run—assuming similar run times for their scrap handling systems—annual energy-cost savings from electric shaker conveyors can total tens of thousands of dollars. Less energy consumption means a lower carbon footprint for stamping plants.
Maintenance. Electric shaker systems, virtually maintenance-free, save hundreds of hours in plant maintenance over a year’s time, enabling staff to focus on other maintenance tasks possibly deferred due to upkeep required on pneumatic shaker systems. Pneumatic conveyors require regular lubrication of air lines and seals to prevent leaks, and this maintenance must be conducted over many thousands of feet of tubing typically found in medium- to large-sized stamping plants.
Flexibility. Electric shaker conveyors offer flexibility to meet a variety of production configurations, and ease reconfigurations as well. For example, MPI’s M-series units are engineered for industry-standard T-slot configurations—common in stamping plants. Pneumatic units prove more difficult to install, and reconfiguring production lines also requires reconfiguration of long-run air lines.
Less noise. Noise in stamping plants is a given—an environmental condition subject to limits set by the U.S. Occupational Safety & Health Administration. Pneumatic shaker systems emitting loud air bursts with each trim clearing present a bigger issue. Electric shaker systems operate almost noiselessly via relatively small motors.
Extensibility. In the age of IoT and Industry 4.0, as stamping operations increasingly utilize plant-floor sensors and controllers that communicate with higher-level manufacturing execution systems, electric shaker systems can be configured to connect with these networks. For example, although most electric shaker conveyors feature simple On/Off switches or wire directly to the press, a variable-frequency drive can provide finer control of the shaker motor’s operation. Also, sensors can monitor shaker amperage to alert operators of a jam. A technician then can clear the jam before scrap backs up. MF