Time：2026-10-21
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In modern industrial manufacturing and non-standard automated assembly lines, automatic screw tightening is a critical process. Yet many production lines frequently suffer from two major defects: screw floating (stand-off) and thread stripping. The industry habitually blames improper torque control and tries to fix it by constantly fine-tuning the electric screwdriver's torque setting. In reality, the more likely culprit is poor control of axial downforce. Each stage of screw driving requires appropriate axial downforce. Traditional mechanisms relying on springs or air cylinders cannot deliver dynamic pressure adjustment. Only a high-precision servo tightening module—with real-time downforce regulation and full-position monitoring—truly solves floating and stripping.
When a screw is driven into a workpiece, the force is not a single tangential torque; it is accompanied by a continuous axial thrust. The required axial downforce differs fundamentally across tightening stages:
Characteristics: The bit feeds the screw axially; the screw has not entered the thread hole and bears no contact load; only posture stability is needed.
Control logic: With no thread-engagement resistance, high-speed feeding causes no thread damage and maximizes cycle efficiency.
Characteristics: The screw tip reaches the thread hole entrance and is about to engage—a high-risk zone for thread damage.
Risk control: If feeding is too fast or axial pressure too high, the starting threads suffer impact, chipping, or plastic deformation, leading directly to jamming and stripped threads.
Characteristics: The screw's starting thread has aligned and engaged stably; the thread pair is in continuous engagement.
Control logic: Threads are fully engaged and guided; medium axial pressure keeps the bit seated in the screw slot, preventing axial movement and ensuring stable torque transmission.
Characteristics: The screw head face is fully seated against the workpiece; the thread pair transitions from engagement to clamp load.
Risk control: Insufficient axial pressure lets the bit slip in the screw slot, preventing torque from reaching the thread pair, causing the screw to stall and ultimately resulting in floating.
Traditional modules use spring or air-cylinder downforce. Spring force varies linearly with compression and cannot be adjusted flexibly; air-cylinder force fluctuates with air pressure and stays constant, unable to switch pressure instantly between stages. This "hard-on-hard" structure naturally struggles to avoid frequent floating and stripping.
To overcome these limits, Danikor servo tightening modules adopt high-precision servo-driven control, elevating axial feeding and downforce to a new level of "flexibility and digitalization." They finely adjust motion and force within millisecond response, allocating the optimal downforce to each stage—ensuring an impact-free, damage-free process and greatly improving yield for sensitive and precision parts.
Initial stage: No axial pressure needed; fast advance compresses idle stroke and improves cycle time.
Hole-entry to thread-contact: Reduce feeding speed in advance; switch to micro axial pressure + low feed speed for smooth initial engagement, avoiding rigid impact and protecting the starting thread form.
Thread engagement: Switch to medium axial pressure + high feed speed for continuous driving, maximizing engagement efficiency while ensuring quality.
Tightening stage: Maintain stable medium axial pressure matched with high torque output at low speed for final tightening, ensuring accurate torque transmission and full seating.
Beyond this, Danikor servo tightening modules use the servo system's built-in high-precision position detection to monitor actual Z-axis depth and position in real time, automatically identifying whether the screw reaches its target seating depth—helping detect floating without extra displacement sensors, saving hardware and cabling cost. They also monitor full-factor data—speed, position, torque, pressure, and time—across the entire process, supporting efficient information exchange with the client/PLC for logical control and providing comprehensive digital traceability for Industry 4.0 smart factories.
With core advantages of real-time controllable downforce and sensorless floating detection, Danikor servo tightening modules give automation integrators and manufacturers a reliable, cost-effective tightening solution—reducing floating and stripping risks while raising assembly-line efficiency and digital management.
Screw floating—where the screw fails to seat fully—is most often caused by insufficient axial downforce during the final tightening stage. When downforce is too low, the bit slips in the screw slot, torque cannot transfer to the thread pair, and the screw stalls before reaching its target depth.
Thread stripping is usually caused by excessive axial pressure or feed speed as the screw tip enters the thread hole. The starting threads suffer impact, chipping, or plastic deformation, which leads to jamming and stripped threads later in the process.
A servo tightening module applies real-time dynamic downforce control, allocating the right pressure to each of the four tightening stages within millisecond response: high speed with no pressure at entry, micro pressure at hole contact, medium pressure during engagement, and stable medium pressure at final tightening—so the process stays impact-free and damage-free.
Instead of adding a separate displacement sensor, the module uses the servo system's built-in high-precision position detection to monitor actual Z-axis depth in real time and automatically determine whether the screw has reached its target seating depth, cutting hardware and cabling cost while improving error-proofing.
Yes. They monitor full-factor data—speed, position, torque, pressure, and time—across the whole process and support efficient information exchange with the client/PLC for logical control, providing digital traceability for Industry 4.0 smart factories.
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