The history of linear motors dates back to the early 1840s, when Wheaton developed small, unsuccessful linear motors. Over the next 160 years, the technology went through three major phases: experimental exploration, development and application, and commercialization. By the 1970s, linear motors began to enter a stage of independent application. Their use has expanded rapidly, leading to the creation of various useful devices such as steel pipe conveyors, coal conveyors, electric doors, and electric windows. Notably, magnetic levitation trains driven by linear motors have achieved speeds over 500 km/h, coming close to the speed of aircraft. In China, research on linear motors started in the early 1970s. Currently, applications include factory automation, electromagnetic hammers, and punching machines. While some progress has been made, there remains a significant gap compared to foreign countries in terms of practical application and promotion. Many domestic institutions are now paying more attention to this field [1]. **The Status Quo of Linear Motors in CNC Machine Tools** In recent years, the integration of linear motors into CNC machines has gained widespread popularity globally. This trend is driven by the need for high-speed and ultra-high-speed machining to improve production efficiency and part quality. A responsive, fast, and lightweight drive system is essential to achieve feed speeds exceeding 40–50 m/min. Traditional systems using "rotary motor + ball screw" can only reach up to 30 m/min with an acceleration of 3 m/s². In contrast, linear motor-driven tables offer speeds 30 times faster, accelerations 10 times greater (up to 10g), and seven times higher stiffness. They also eliminate dead zones and provide high-frequency response due to low inertia. In 1993, Germany's ZxCell-O introduced the world’s first HSC-240 high-speed machining center powered by a linear motor. It reached a spindle speed of 24,000 rpm, a feed rate of 60 m/min, and an acceleration of 1g, achieving a contour accuracy of 0.004 mm at 20 m/min. The U.S. company Ingersoll followed with the HVM-800, featuring a 20,000 rpm spindle and a 75.20 m/min feed rate. Since 1996, Japan has developed various linear motor-driven machines, including horizontal machining centers, high-speed tools, ultra-high-speed small machines, and precision mirror-processing equipment [1]. In China, Zhejiang University developed a press machine driven by a linear motor, while the Institute of Production Engineering designed a parallel mechanism coordinate measuring machine using a cylindrical linear motor [2]. In 2001, Nanjing Sikai launched a self-developed digital linear motor lathe. At the 8th China International Machine Tool Exhibition in 2003, Beijing Electric Power High-Tech exhibited the VS1250 linear motor machining center, with a spindle speed of 15,000 rpm. **How Linear Motors Work** A linear motor converts electrical energy directly into linear motion without any intermediate mechanical conversion. It can be viewed as a radial cut of a rotary motor, flattened into a plane, as shown in Figure 1. The side that evolved from the stator is called the primary, and the one from the rotor is the secondary. In practice, their lengths are adjusted to ensure consistent coupling over the travel range. Typically, the primary is shorter than the secondary, which helps reduce manufacturing and operational costs. The working principle of a linear motor is similar to that of a rotary motor. For example, in a linear induction motor, when the primary winding is connected to an AC power source, it generates a traveling wave magnetic field. This induces an electromotive force in the secondary, generating current that interacts with the magnetic field to produce electromagnetic thrust. If the primary is fixed, the secondary moves linearly under the thrust; otherwise, the primary moves. **Linear Motor Drive Control Technology** A successful linear motor application requires not only a high-performance motor but also a reliable control system that meets technical and economic requirements. With advancements in automatic control and microcomputer technology, various control methods have emerged. Research in this area can be divided into three categories: traditional control, modern control, and intelligent control. Traditional techniques like PID feedback and decoupling control are widely used in AC servo systems. PID control incorporates past, present, and future information, offering strong robustness. Decoupling and vector control techniques are often used to enhance performance. When the object model is stable and linear, traditional control methods are effective. However, in high-precision applications, nonlinear effects and environmental changes must be considered. This has led to the development of modern control methods such as adaptive control, sliding mode control, and robust control. In recent years, intelligent control methods like fuzzy logic and neural networks have also been applied. These methods combine existing techniques to improve control performance [3]. **Examples of Linear Motor Applications in CNC Machines** **Piston Turning CNC System** Due to its fast response and high accuracy, linear motor-based linear motion mechanisms have been successfully used in CNC turning and grinding of special-shaped parts. The National University of Defense Technology developed a high-frequency, large-stroke digital feed unit based on a linear motor. When used in CNC piston machines, it features a table size of 600mm × 320mm, a stroke of 100mm, and a maximum thrust of 160N with an acceleration of up to 13g. Since the linear motor mover is fixed to the table, only closed-loop control is used. Figure 2 shows the control system schematic. **Open CNC System with Linear Motor** This system uses a PC and an open programmable controller to form a numerical control system. It employs a general-purpose microcomputer and Windows platform, with a motion controller as the core. The overall design is shown in Figure 3, consisting of a PC, motion control card, servo drive, linear motor, and numerical control table. The motion control card model is PCI-8132, which supports two-axis motion control, linear and circular interpolation, and position feedback. System software is developed on the Windows platform using modular programming. It includes user input/output interfaces and preprocessing modules. The G-code is read, compiled, and executed to drive the linear motor. The program flow is illustrated in Figure 4. In this system, the Parker 406LXR series linear motor is used. For a two-axis NC workbench, the X-axis uses the 406T07 model with a 550mm stroke, and the Y-axis uses the 406T05 model with a 450mm stroke. **Conclusion** High-speed machining centers equipped with linear servo motors have become a key technology in the global machine tool industry. They are being adopted in automotive and aerospace sectors, showing promising results. Linear motor technology has also entered industrial applications worldwide. However, domestic research in this area is still in its early stages, with a significant gap remaining. This article discusses the current applications of linear motors and highlights that many technical challenges remain to be addressed in the future.

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