Servo electric screwdrivers and pneumatic electric screwdrivers are both mature products. They mainly solve the power-source problem for driving screws, reduce labor intensity, and offer simple torque-adjustment functions that basically satisfy ordinary torque-control needs. Because these tools are inexpensive, mature, and easy to use, they are widely used in all kinds of screw-driving applications. They can be operated manually or embedded in automated equipment to replace manual labor completely.

A servo electric screwdriver consists of:

• A servo motor that supplies torque

• A coupling connected to the motor output shaft

• A fixed sleeve and bit attached to the lower end of the coupling

• A flange structure that is fastened to the servo motor for support and protection

Inside the bit sleeve is a spring; a retaining ring sits at the upper end of the spring, and a mounting hole is located between the spring and the ring. The connecting seat and the bit are joined through the sleeve, and the bit can be installed or removed quickly. Compared with ordinary electric screwdrivers, servo electric screwdrivers achieve a higher tightening yield; they are mainly used for small screws and guarantee consistent torque every cycle, greatly reducing common defects such as floating (gaps), thread stripping, and missed tightenings.

In a pneumatic electric screwdriver, the screwdriver body, suction tube, and suction nozzle are sealed together to form a closed cavity. The body and the tube are threaded together; a spring inside the tube pushes against the nozzle so the nozzle can slide back and forth. During the tightening operation, air is drawn through the suction port, creating negative pressure in the cavity; the suction nozzle picks up the screw for automatic feeding, and the bit—connected to the screwdriver body—then drives the screw home.

Differences between servo and pneumatic electric screwdrivers

Pneumatic screwdriver

• Power source: compressed air

• High power-to-weight ratio, about 25 % cheaper than a servo unit

• No reaction torque, so it is widely used on the shop floor

• Advantages: high speed, fast rundown, relatively low cost

• Disadvantages: loud noise, torque cannot be fully controlled

• Main use: driving small screws into large components

• Features: speed is adjustable, clutch can disengage automatically, can drive screwdriver bits; light weight, small size, easy to control; usually has auto-shut-off at preset torque; often equipped with automatic screw feeding; noise and vibration are obviously lower than in older designs, improving working conditions

Servo electric screwdriver

• Delivers stable, traceable torque values, but its use is limited by installation space, joint accessibility, and higher price

• Power source: electricity

• Characteristics: high precision, easy operation, but higher price and produces reaction torque

In a threaded joint, the correct preload is the key to long-term reliable operation. In precision assemblies—e.g., bolts in compressors or high-pressure piping—too little preload allows the bolt to loosen and fall out, while too much preload over-stretches the bolt and causes fatigue failure, shortening bolt life. If an ordinary pneumatic screwdriver is used in these cases, the preload depends almost entirely on the operator’s feel; accurate control is impossible, and normal equipment operation cannot be guaranteed. A servo electric screwdriver, however, can deliver an accurate torque value, thereby controlling the preload precisely and ensuring a high-quality threaded joint.

Enterprises should choose the screwdriver that best matches their product’s application scenario, so that they can raise capacity, secure quality, and cut production costs, finally achieving better economic returns.