Direct-drive linear (DDL) motion technology had its start in the machine tool industries: high-quality machining, honing, grinding, punching, and laser cutting. Linear motor systems have expanded into gantries/material handling, flying cut-off equipment, metal forming, assembly shuttles/conveyors, and food-processing machinery. See photos, suppliers, links.

This distinct motion technology eliminates all rotary-to-linear conversion devices between motor and load—such as ball screws, gear boxes, rack-and-pinions, and belts- to obtain high-dynamic performance in a growing number of applications.

Linear drive systems offering both automatic reversal of the traversing nut and the ability to adjust speed almost invariably require a variety of sometimes costly components. These include control systems, sensors, clutches, encoders, reversible variable-speed motors, and gearboxes. Training personnel to operate these systems further adds to the overall investment. What's more, equipment investment and maintenance is a specialized business requiring skilled technicians and labor.

Highly precise linear positioning systems, such as those used to focus and scan in measuring and inspection equipment often need two different motion modes: a rapid one (100 mm/sec) followed by a slower one (20 nm/sec). The fast mode reduces move time, while the slower mode ensures precision.

Here's a look at the pros and cons of various direct-drive rotary systems. Direct-drive rotary (DDR) systems are available in frameless, housed, and the newly developed cartridge motor format.

Servodrives synchronize rotary and linear movements. To fully and efficiently control the overall winding process, Elmo Motion Control designed a master-slave electronic-cam system in which the target-spool rotary motor serves as the master, and a linear motor acts as a slave.

Some adjustable-speed drives can be equipped with capabilities to maintain operations even when there is a power outage for short periods of time. Many things can cause short duration power problems, including lightning, mometary high-voltage faults, high-voltage switching, amongst other things. These short disruptions can reek havoc to critical processes. This article deals with overcoming these problems, for example, by equipping the drive with some form of ride-through capability.

This article is part two of a series of articles and talks about the types of adjustable-speed drives best suited to common applications and how to avoid pitfalls. Seven of the most frequently encountered applications are discussed at length.

The world of mounting adjustable-speed drive controllers directly on to motors is changing. Although motors with built-on controllers have been made, the applications remained limited. But new technologies for industrial and commercial applications are enabling mounting drive controllers directly to motors. Technological breakthroughs will allow integral horsepower AC motors to include more sophisticated controls.

A new piezoelectric device that turne a screw ensures linear positioning with high precision and range. Now screw travel entails no creep or hysteresis. Its called a Picomotor and it was designed originally as a position for lasers and other optic systems. As it turns out, its uses run well beyond such devices.

This article answers questions on electrical adjustable-speed drives.  Examples include, "is a digital drive design better than an analog design," "when should a vector control be chosen over a conventional converter?"

This is a Q&A article on lubrication tips.  Questions include how to determine whether or not to use oil or grease in a particular machine application; and if solid lubrication would help equipment operate more effeciently under high loads at high temperatures.

Where it was once condidered too costly to use regeneration with adjustable-frequency drives to return energy to the AC power line, line regeneration is now one of the more common schemes used as a viable method for controlled deceleration.

To eliminate jarring starts and stops of a high-inertia cable system, use a flux vector adjustable speed drive.  This will lower power requirements, boost productivity and reduce component wear and tear.

One way to achieve higher productivity and quality at lower operating costs is to convert a single-axis, high horsepower drive to a multi-axis, servo-controlled operation.