Motion Control

Choosing Stepper- or Servo-Driven Actuators to Replace Air Cylinders

Pneumatic (air) cylinders are widely used in industrial automation due to their low per-axis cost and high-speed/force capabilities. They have a long history of being popular workhorses in the automation industry. However, there are many reasons to use electric actuators in place of air cylinders: reduced machine downtime, reduced energy consumption, increased precision, and increased speed. In addition, electric actuators can be powered by servo or stepper motors, in conjunction with a control device, to provide linear motion. Advantages of Electric Linear ActuatorsReduced downtime. Electric linear actuators (whether screw- or belt-driven) are very low-maintenance. Regreasing may be the only regular maintenance necessary, and many screw-driven models are lubricated for the life of the actuator.

Posted in: Articles, Aerospace, Motion Control

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Custom Machines Create Engine Lip Skins on Boeing Aircraft

MJC Engineering, a custom machine tool builder in Huntington Beach, CA, specializes in metal-spinning machines for such applications as sheet spinning, flow forming, wheel spinning, and rotary forging. The company was commissioned to build a series of metal-spinning machines for GKN for use at its plants in Camarillo, CA and Orangeburg, SC. These machines produce lip skins for the engine housings on Boeing 777X and 737MAX aircraft. Using CNC from Siemens Industry (Elk Grove Village, IL) and robotic handling technology — in addition to its proprietary servopump-controlled Green Power™ hydraulic power unit that saves up to 40% on energy — the MJC team devised a unique solution to an engineering challenge brought to them by GKN.

Posted in: Application Briefs, Aviation, Motion Control

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Precision Robotics and Automation: Hexapods Advance Production Processes

Hexapods — six-legged parallel-kinematic machines — are quickly gaining ground in a broad range of industrial automation applications after “learning” how to directly communicate with PLC or CNC controllers via Fieldbus interfaces. As far as the semiconductor and electronics industry, automobile industry, and precision assembly are concerned, many production processes have become inconceivable without them. Today, the six-axis positioning systems are available with load capacity from 2 kg to 2000 kg, and travel from 10 to hundreds of millimeters while maintaining submicron precision. Hexapods are used for aligning the smallest optical components in the latest silicon photonics production processes, for controlling automated labeling machines, and positioning entire body parts for automotive production. The intrinsic hexapod features contribute to a wealth of new possibilities in robotics.

Posted in: Articles, Motion Control, Machinery & Automation, Robotics

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Motor Controller Provides Custom Electronic Control Solution

A Fortune 200 company needed a turnkey, DC voltage, agency-compliant electronic control solution capable of providing motion control with memory position capabilities and auto run/sense features for a multi-motor application involving four motors. Particularly important to the design criteria was the development of an interactive system of wireless remote control capabilities and other user interface devices, including iPhone and iPad interconnect devices. It was a complicated job, and the company would need to partner with experts who could deliver a time- and cost-effective solution.

Posted in: Application Briefs, Motors & Drives

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Advantages of Servo Motor and Direct Drive Technology

For many years, stepper motors have been the most popular type of electric motor designed into instrumentation for a wide variety of reasons. Stepper motors have become increasingly commoditized, and can be sourced easily. In addition, the growing “maker movement” has simultaneously made them more popular and reduced their cost. Unlike servo motors, stepper motors don’t require tuning to optimize their performance. What’s more, scaling and motion commands are typically quick and simple to execute using stepper motors. Servo motors often require a bit more expertise in executing complicated (torque, velocity, or position) loop closures. Finally, micro-stepping allows most modern drive electronics to step or increment a stepper motor to a resolution of 50,800 steps per revolution or higher.

Posted in: Articles, Motion Control, Motors & Drives

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An Inside Look at Electromechanical Power-Off Braking Options

Making the right choice between spring set and permanent magnet brakes can impact safety, durability, maintenance, and performance. Power-off brakes are designed to hold or stop motion in the absence of power. Adding an electrical current releases the brake, freeing the load for motion. Given the safety ramifications of keeping a system locked in place until it is powered up, motion control system designers tend to specify power-off brakes more often than power-on brakes. There are, however, two different failsafe brake technologies: one uses compression springs to hold its load in place, and the other uses permanent magnets. Each has specific strengths and weaknesses, and knowing the difference can impact safety, durability, cost, and performance.

Posted in: Articles, Motion Control, Electronic brake controls, Springs, Magnetic materials

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Multiphysics CAE of a Shock Absorber

Figure 1. CAE simulation of a shock absorber. Shock absorbers are important parts of vehicles. The shock absorber is used to observe the vibrations from shock loads due to irregularities of the road surface, and operates without affecting the stability, steering, or handling of the vehicle. Generally, for light vehicles, cylindrical coil springs are used as suspension elements. The application described in this article attempts to analyze performance of a shock absorber with different suspension springs. This analysis includes comparative modeling and analysis of solid height, damping performance, oscillation capabilities of closed coil conical and cylindrical compression springs, and a suggested suitable design for improved performance.

Posted in: Application Briefs, Motion Control, Dampers and shock absorbers, Springs, CAD, CAM, and CAE, Performance tests

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