With the advancement of direct drive technology, the comparison between linear motors and traditional "rotary servo motor + ball screw" drive systems has become a hot topic in the industry. Many of the world's leading manufacturers of machining centers are now incorporating linear motors into their high-speed machine tools, recognizing their potential for enhanced performance.
In terms of precision, linear motors offer significant advantages. They eliminate interpolation hysteresis caused by mechanical transmission, resulting in higher positioning, repeatability, and absolute accuracy. These benefits are achieved through position detection feedback control, which is more straightforward to implement. A linear motor can achieve a positioning accuracy of up to 0.1μm, while the traditional system typically reaches 2–5μm. The latter requires a complex setup including CNC-servo motors, gapless couplings, thrust bearings, cooling systems, high-precision rolling guides, nut seats, and a workbench with a closed-loop transmission system. This makes it heavier and more demanding in terms of grating scale accuracy. To maintain stability, the traditional system often needs dual-axis driving. In contrast, linear motors generate more heat and require advanced cooling solutions, which increases their cost.
When it comes to speed, linear motors shine. They can reach speeds of up to 300 m/min with accelerations of 10g, while ball screws max out at around 120 m/min and 1.5g. This gives linear motors a clear edge in both speed and acceleration. Once the heating issue is fully resolved, their performance can be further improved. On the other hand, ball screw systems have inherent limitations in speed and are difficult to enhance significantly over time.
Regarding lifespan, linear motors have a major advantage. Since there is no physical contact between the moving and fixed parts, they do not suffer from wear due to high-speed reciprocating motion. This ensures consistent positioning accuracy over long-term use, making them ideal for high-precision applications. Ball screws, however, experience wear from friction during high-speed operation, which can degrade their accuracy over time. As a result, they struggle to meet the demands of precision-critical tasks.
Overall, linear motors represent a significant leap forward in motion control technology, offering superior performance in accuracy, speed, and longevity—though they come with higher costs and technical challenges that must be addressed.
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