Motion Control

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, Optimization, Energy conservation, Electric drives, Electric motors

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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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Rotary Valve

RotaVal Ltd. (Wiltshire, UK) introduced a heavy-duty rotary valve for use where solids handled and operating conditions combine to cause abrasive erosion within the valve. It has on-site component replacement. The valves are used in discharging materials such as cement, PFA, granite dust, silica sand, and mineral powders under adverse pressure conditions. Standard valves are manufactured in cast iron, SG iron, Ni-hard, and carbon steel. The replaceable body liner can be hard chromed or ceramic coated. Rotor shaft sealing options include various types of gland packing, mechanical seals, and air or grease purge.

Posted in: Products, Motion Control

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Voice Coil Actuator

The LAH15-19-000A linear voice coil actuator from BEI Kimco (Vista, CA) provides low hysteresis/ low friction with bi-directional position control. It is suited for applications where low friction and high force accuracy are needed. The low-friction design features a patent-pending symmetrical flex circuit that prevents friction caused by movement. A solid brass ball cage with captured steel balls also reduces friction. The actuator offers a hysteresis of 10 mN. Other features include a peak force of 4.7 N, a total stroke of 7.4 mm, and a compact size of 38 mm in diameter by 48.3 mm in length.

Posted in: Products, Motion Control

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Compact Robot

ABB Robotics (Auburn Hills, MI) introduced the IRB 1660ID compact robot for arc welding and machine tending applications. It features a DressPack design that allows users to program and simulate predictable cable movements, a rigid upper arm with a reach of 1.55 m, and a payload of 6 kg. It is able to accommodate heavier weld torches, and provides wire feeding control near the arc. TrueMove™ technology provides 0.05-mm path repeatability. The integrated DressPack allows the robot to move at maximum acceleration and speed for machine tending applications. The risk of collision in confined spaces is also eliminated, and the 1,390° working range of axes 4, 5, and 6 enables agility in CNC machines.

Posted in: Products, Manufacturing & Prototyping, Motion Control

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Block Spindle

Suhner Industrial Products Corp. Automation Division (Rome, GA) introduced the BEX8 high-speed machining block spindle capable of maintaining rigidity and precision at operations up to 25,000 rpm. The spindle weighs 33 lbs. and can be mounted directly onto robotic arms for fully automated machining operations in automotive, appliance, off-highway, and other industries. The standard motor supplied is either 0.37kW or 0.75kW, and the standard toolholder supplied is ER20.

Posted in: Products, Manufacturing & Prototyping, Motion Control

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