A torque screwdriver limits rotational force to a specific value. When the set torque is reached, the driver clicks, slips, or signals - preventing over-tightening. This matters whenever fastener tension is critical: electronics, aerospace, medical devices, firearms, and data centre equipment.
Types of Torque Screwdrivers
| Type | How It Works | Torque Range | Best For |
|---|---|---|---|
| Preset | Factory-set to one torque value; clutch slips at that value | 0.04 – 13.5 Nm | Production lines, repetitive work at one spec |
| Adjustable | User-adjustable dial or collar sets the target torque | 0.1 – 27 Nm | General workshop use, varying fastener specs |
| Digital / Electronic | LCD display shows real-time torque; beeps or vibrates at target | 0.005 – 13.5 Nm | Laboratories, quality control, audit-ready work |
| Cam-Over | Free-spins after reaching torque (no further tightening possible) | 0.02 – 6 Nm | Delicate electronics, optics |
When You Need a Torque Screwdriver
- Electronics assembly - circuit boards and connectors crack under excess torque
- Aerospace and defence - every fastener has a documented torque spec for safety
- Medical devices - prosthetics, implants, and surgical tools require exact fastener tension
- Data centres - server rack screws have torque specs to avoid damaging server chassis
- Firearms - scope mounts, action screws, and accessories have specific inch-pound specs
- Automotive - some interior trim and sensor screws require torque-limited fastening
Calibration
Torque screwdrivers must be calibrated regularly to maintain accuracy. Most manufacturers recommend annual calibration, or every 5,000 cycles - whichever comes first. ISO 6789 governs torque tool calibration standards. Adjustable drivers should be set to the lowest value when stored to relieve spring tension.
Store adjustable torque screwdrivers at their lowest setting. Leaving the spring compressed at a high setting causes it to lose accuracy over time.
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