Before the advent of linear motors, almost all linear motion required complex transmission mechanisms to achieve this function. With the development of linear motors, the space for traditional structures has been continuously squeezed. In certain special environments, such as under heavy loads and vertical motion, traditional linear structures (mainly lead screw modules) still play an irreplaceable and excellent role. Furthermore, linear motors are increasingly occupying more and more applications. The replacement of traditional mechanical structures by linear motors has become a recognized trend in the industry and is being accepted by more and more sectors.
So what kind of "charm" allows linear motors to suddenly become the industry's "new favorite," even overshadowing ball screw modules that have dominated the market for many years?
Advantages of linear motors
The advantages of linear motors can be summarized as follows:
(1) In terms of mechanical structure: Linear motors have a very simple mechanical structure. There is no mechanical contact during movement, and the power transmission is generated in the air gap. There is no friction other than the linear motor guide rail. Linear motors do not need to go through intermediate conversion mechanisms to generate linear motion directly, which greatly simplifies the system structure and reduces the moment of inertia.
(2) In terms of motion control: the dynamic response performance and positioning accuracy of linear motors are greatly improved, and their reliability can be guaranteed. Since linear motors eliminate intermediate transmission links that affect accuracy, the accuracy of the system depends almost entirely on the position detection element, and with a suitable feedback device, it can even reach sub-micron level accuracy.
(3) In terms of operation: The linear motor stroke is theoretically unlimited and its performance will not be affected by changes in the stroke size.
(4) In terms of smooth motion: The linear motor has no other mechanical connection or conversion device except for the linear guide rail or air bearing that plays a supporting role, which makes it run very smoothly when equipped with a high-performance guide rail.
(5) In terms of acceleration: linear motors can provide a large acceleration and a wide speed range. The maximum acceleration can reach 10G, and the speed can range from a few micrometers per second to several meters. Its advantages are more significant, especially at high speeds.
(6) In terms of electromechanical maintenance: linear motors are easy to maintain. Due to the small number of parts and the lack of mechanical contact during movement, the wear of parts is greatly reduced. They require little or no maintenance and have a longer service life.
(7) In terms of speed: linear motors are suitable for high-speed linear motion because there is no centrifugal force constraint. Ordinary materials can also achieve high speeds. Usually, the gap between the primary and secondary is maintained by air cushions or magnetic cushions. There is no mechanical contact during movement, so there is no friction and noise in the moving parts. Therefore, there is no wear on the transmission parts, which can greatly reduce mechanical loss and avoid noise caused by cables, steel cables, gears and pulleys, thereby improving overall efficiency.
(8) In terms of adaptability: The primary iron core of the linear motor can be sealed with epoxy resin as a whole, which has good anti-corrosion and moisture-proof properties, making it easy to use in humid, dusty and harmful gas environments. Moreover, it can be designed into various structures to meet the needs of different situations.
Key considerations for linear motor applications
Linear motors possess unparalleled advantages, but their inherent limitations include the following drawbacks. Therefore, when making a design selection, a comprehensive consideration is necessary to choose the optimal configuration. Key considerations include:
(1) Linear motors consume a lot of electricity, especially when performing high load and high acceleration movements, the instantaneous current of the motor will bring a heavy load to the power supply system of the equipment.
(2) The high vibration of linear motors is also a shortcoming that cannot be ignored. The dynamic rigidity of linear motors is extremely low, which cannot play a buffering and damping role. When moving at high speed, it is easy to cause resonance in other parts of the equipment, thus affecting the overall performance of the equipment.
(3) Linear motors generate a lot of heat. The linear motor mover fixed at the bottom of the workbench is a high-heat component. If the installation position is not conducive to natural heat dissipation, it will pose a great challenge to the constant temperature control of the equipment.
(4) Linear motors cannot self-lock. In order to ensure operational safety, the motion axis driven by the linear motor, especially the vertical motion axis, must be equipped with an additional locking mechanism, which increases the complexity of the equipment.
summary
As is well known, the main advantages of linear motors are high speed and high acceleration. Taking machine tools as an example, during machine tool processing, when the acceleration exceeds 10 m/s², the saved auxiliary time is not significant in terms of the overall machining time; high acceleration is only meaningful in machining processes with very short machining times. In other words, for the cutting and machining of single, complex parts such as molds and fan blades, the advantages of linear motors are not obvious.
For the reasons mentioned above, equipment manufacturers that choose to develop linear motors adopt a strategy of maximizing their strengths and minimizing their weaknesses. First, they apply linear motors to applications involving mass production, numerous positioning movements, and frequent directional changes, such as automotive parts processing machine tools, rapid prototyping machines, and semiconductor manufacturing machines. Second, they apply them to applications with low loads and a wide range of processes, such as electrical discharge machining (EDM) machines, plasma cutting machines, and waterjet cutting machines.
As a registered member of the Japan MECHATROLINK Association and CC-LinK Association, Aoyin has accumulated over ten years of R&D experience in Japan and possesses leading technology in the field of linear motors. It has extensive technical experience in the production and application of various types of linear motors and serves a wide range of well-known companies. In addition, Aoyin can provide non-standard design and special customization services to meet the needs of special users.
