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Everything you should know about electromechanical cylinders

Learn more about a suitable replacement for traditional hydraulic or pneumatic rod-style cylinders

Electromechanical cylinders are shown.

When it comes to metal fabrication, the applications for an electromechanical cylinder are quite varied, including press-fitting, punching, crimping, bending, embossing, assembling, riveting, deep drawing, shaping, bonding, inserting, welding, clipping, testing, and measuring.

For fabrication applications such as forming and riveting, electromechanical cylinders (EMC) present new options when back-and-forth actuation is required, especially with heavy load and force requirements. A thorough understanding of the new developments in EMC technology can help to improve machine operation and productivity.

What Is an EMC?

An EMC is a preengineered, compact, screw-driven, rod-style actuator. Rod-style cylinders are designed to push and pull mechanical elements of a more complex system, such as drawing material to change its shape, function, or assembly.

Unlike the traditional hydraulic or pneumatic rod-style cylinders, an EMC is designed to be a safer, quieter, and cleaner solution that only requires energy on demand rather than constant power. It uses a low-friction ball screw assembly or a high-force roller screw assembly to convert the rotational motion from an electric motor to a linear extend or retract motion of a piston rod. With the use of precision-machined ball or roller screws, machinery designers and technicians can achieve infinite positional requirements with accuracies measured in microns.

Which Applications Could EMCs Be Used for in Metal Fabrication?

The applications for an EMC are quite vast when it comes to metal fabrication. Applications include but are not limited to press-fitting, punching, crimping, bending, embossing, assembling, riveting, deep drawing, shaping, bonding, inserting, welding, clipping, testing, and measuring.

Historically, when lower force requirements were needed, pneumatic actuation could be employed to provide the required force. Traditional pneumatics must have air compressors and plumbing to supply the air required to perform actuator tasks. In some cases this could work, but when working with a pneumatic cylinder, a fabricator is typically limited to having two positions: fully extended or fully retracted.

For higher force requirements or multiple position needs, hydraulics traditionally are the go-to solution for metal fabrication applications. Hydraulics are capable of extreme forces, but they have the disadvantage of fluid leaks and high-pressure hose blowouts.

When the application requirements fall within the force range of an EMC, a metal fabricator has the ability to save money on energy costs and reduce its carbon footprint with energy on demand while avoiding safety hazards and cleanliness issues. In addition, EMCs allow a manufacturer to have the flexibility to change position for different tooling and fixtures for producing different parts on the same machine.

How Has EMC Technology Changed Over the Years?

EMCs, also known as electromechanical actuators, were first introduced to the automation industry in the 1960s. Since that time, the technology has come a long way, from the actuator construction itself to sensors, motors, and drives, and even the mechanical system cooling.

Because of the rotary motion of the screw assembly, today’s EMCs require anti-rotation of the ball or roller nut to turn rotary motion into linear motion. EMCs now have the anti-rotation feature internal to the actuator, so applying torque to the connection components is no longer required. The connection components and mounting technology have not changed much, but other accessories, such as force sensors or external guidance, can now be integrated into them. Positional and home magnetic field sensors can also be applied to the EMC.

Motors and drives have evolved as well. Today they have higher output capacity, more safety-oriented capabilities, are able to provide Industry 4.0 capabilities, and have absolute encoders for positional feedback accuracy.

An individual EMC is shown.

To dissipate heat during operation, some new EMCs have water-cooling features.

The mechanical elements of the ball screw or roller screw drive inherently create heat generation due to friction. Heat can cause steel to expand, generating more wear to the rolling elements of the nut assembly and spindle. When this happens, a manufacturer has to schedule cool-down periods or ensure that an oversized EMC was specified for the application so that it can achieve the desired lifespan. Developments to counteract this include sealed units submerging the mechanical screw components in an oil bath to dissipate heat and gun-drilling the spindles to allow for water cooling for your highest power output needs. This water-cooling feature is new and can be found on recently introduced high-power actuators.

Anything Else to Consider Related to EMCs?

A manufacturer should consider the lifespan of its machines and of the components that are put into the machines. It also helps to lean on local experts to assist with sizing and application questions.

If a company is replacing traditional pneumatics and hydraulics, it should know the force needed in the application and not what the current system is capable of. Sizing an application based on the incumbent system’s maximum capability could have a negative effect for the new EMC, motor, and drive sizing.

Finally, quality should be a top priority with an electromechanical solution. This will save companies time and money in the long run.

About the Author

Carter Paden

EMC-HP Product Manager

5150 Prairie Stone Pkwy.

Hoffman Estates, IL 60192