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	Ballscrews? Or linear motors? It’s a popular debate, but it’s like comparing apples to oranges. One technology does not fit all. And only a thorough examination of each individual application—instead of a cursory comparison of specifications—will lead you down the right path. On the up side, ballscrews deliver high levels of accuracy and thrust, as well as optimal deceleration during loss of power. They provide extremely beneficial dampening, which minimizes chatter. They are ideal for applications requiring less than 13 feet of travel in ferrous material. Low-speed ballscrews are optimal for applications with low feedrates or low levels of spindle utilization. Unfortunately, the maximum rpm of the ballscrew depends on its diameter and length, which can be problematic in applications with longer workpieces. And as the mass of the ballscrew increases with its length, acceleration is limited and stiffness decreases. Linear motors, meanwhile, provide high levels of velocity and acceleration. Since there is no correlation between performance and the length of travel, linear motors can provide fast drive speeds regardless of size. This makes linear motors desirable for a variety of applications, like extremely large structural airframe components. On the downside, the attractive force of a linear motor’s magnets is typically three times greater than the thrust force. So a motor with 2,000 lb. of thrust would subject the linear guideways to an additional 6,000 lb. load, potentially crushing the linear guideways. Controlling deceleration during a power outage is a challenge with linear motors and the electromagnetic fields created by them can prove to be a safety issue for operators with pacemakers. So with all of the pros and cons, which is the best way to go? There is no perfect answer and no single solution that’s optimal for every application. In evaluating a high-performance machining center, and the technology supporting it, compare the requirements of a particular application to the strengths and limitations of the available technologies. Rather than getting into "spec wars," work closely with your supplier. Make sure the supplier not only provides the right technology, but also supports the application after installation. Ballscrew and linear motor technology has improved over time and, based on current industry research and development, this evolution will continue. The debate over which technology is superior may also continue, but one thing is certain: the application approach will always help you select the right technologies. Copyright © 2001 - 2008 by Makino, Inc. All rights reserved.