In the manufacturing of modern household appliances, industrial machinery, and other equipment, assembly has ceased to be a task that requires extensive time and manpower. As the specifications of 3C products become increasingly smaller, users are placing ever-higher demands on product volume and the speed of product updates. Consequently, conventional manual assembly methods—both in terms of skill level and speed—can no longer meet these requirements. Thus, automated assembly lines have emerged as a natural response to these challenges.

Among all assembly tasks, tightening screws is the one that involves the greatest workload and is the most tedious. Just consider the smartphones we use in our daily lives—each one requires hundreds of screws to be securely fastened into place. In new-energy vehicles, the number of screws used for lithium batteries can even exceed a thousand. Most importantly, every single screw must be tightened with precise angles and torque specifications; any deviation whatsoever could lead to serious consequences. If these tasks were performed manually by ordinary workers, not only would labor costs be virtually unlimited, but the risk of product defects would also soar. Therefore, in virtually every assembly scenario, a screw-tightening system has become an essential piece of equipment.

Currently, tightening systems on the market are broadly categorized into servo tightening systems and hollow-cup motor tightening systems.

Servo tightening system:

A servo tightening system is an automated tightening device that allows the torque, angle, and other output parameters of a conventional screwdriver to vary freely in response to an input signal (or a set value). The so-called servo tightening system relies primarily on the precise pulse-based positioning capability of a servo motor to perform accurate tightening operations. Essentially, when the servo motor receives a pulse, it rotates by a corresponding angle, enabling precise control over both torque and positioning. Moreover, the pulses emitted by the servo motor after rotation can be synchronized with the pulses it receives, ultimately providing feedback on parameters such as torque during the tightening process and achieving closed-loop control.

The basic servo tightening system consists of three components: the controller, the cable, and the servo screwdriver.
Controller: Includes a built-in power supply, servo driver, display screen, and main control board. Its primary functions are to issue commands to the screwdriver, drive the operation of the servo motor, and display feedback values.

Cables: Their primary function is to transmit commands and feedback data.

Servo screwdriver: In addition to the accessories found in a conventional screwdriver, this model features a built-in servo motor. Its primary functions include performing tightening operations according to instructions and providing feedback on parameters such as torque and rotation angle.

Main application scenarios: Servo tightening systems are primarily used in assembly applications that demand high precision, zero error, and data feedback. Their main drawback stems from the characteristics of servo motors: they are not suitable for applications requiring high torque with large inertia.

Hollow-cup motor tightening system:

The key features of the hollow-cup motor tightening system stem from the coreless nature of the hollow-cup motor. As is well known, the internal structures of conventional linear motors, stepper motors, and servo motors all require rotors made of iron cores. However, the absence of an iron core in the hollow-cup motor allows it to be significantly smaller and lighter than conventional motors. Moreover, its performance is superior to that of conventional iron-core motors: while the energy conversion efficiency of a typical iron-core motor tops out at around 70%, the hollow-cup motor can achieve an efficiency of up to 90%. Additionally, the hollow-cup motor boasts a response speed that far surpasses that of iron-core motors.

This characteristic enables the electric screwdrivers used in hollow-cup motor tightening systems to be exceptionally lightweight. Currently, most hollow-cup motor tightening systems on the market still adopt a screwgun-like structure; when paired with encoders and controllers, they can also provide feedback on tightening data. However, due to the higher cost of hollow-cup motors, hollow-cup motor-based tightening systems naturally tend to be more expensive than servo-based tightening systems. Typically, the cost of a hollow-cup motor-based tightening system from foreign brands ranges around 30,000 to 40,000 yuan per unit. Therefore, manufacturers with relatively low torque requirements generally still opt for the more affordable servo-based tightening systems.

Main application scenarios: Suitable for high-torque applications such as the automotive industry, where hollow-cup motors are used in tightening systems manufactured by well-known brands like Matador and Atlas. These motors are primarily targeted at the automotive sector. However, in terms of precision requirements, they still do not reach the level of servo motors.

In addition to the basic tightening system, a complete machine tightening system must also be equipped with a feeder, PLC, computer, and display screen. This allows the system to be integrated into an automated production line as a fully automated machine-tightening system.