Torque Screwdriver Calibration Basics

Torque assembly tool calibration program from Express Assembly

Calibrating a torque screwdriver or torque meter insures that it performs within its technical specification. Most torque screwdrivers have a minimum and maximum torque value, along with a standard torque deviation percentage. When you have a screwdriver calibrated, you ensure that a screwdriver maintains its standard torque deviation percentage at its minimum, maximum, and several torque values between these points.

What do I get when I send a screwdriver for calibration?
When you send a tool for calibration, you are asking technicians to compare the instrument to a traceable standard maintained by the National Institute of Standards and Technology (NIST). If the tool is “out of cal”, it is adjusted to meet the standard. You’ll get a report showing how far out of calibration the instrument was before, and how far out it is after.

How do I know if a tool needs to be calibrated?
Sometimes, you’ll note that something isn’t working right. Maybe the fasteners are under or over fastening or the driver head is wearing strangely. Often, however, you won’t notice anything obvious but the tool is no longer meeting the standard maintained by the National Institute of Standards and Technology (NIST).

How often should a tool be calibrated?
The default period between recalibrations is 5000 cycles or 12 months, but it depends on how the tool is used. Tools that receive heavy use, are tossed around, or used in extreme temperatures will need to be calibrated more often. If torque tolerance affects the safety of an application – think aircraft or auto assembly, for example – you will also want to calibrate your tools more frequently. Torque screwdrivers that are overloaded by 25% or more of its maximum should also be recalibrated.

What if I don’t calibrate my torque screwdriver?
Regular torque tool calibration and re-calibration guarantees repeatable accuracy and adherence to international assembly tool standards. If you delay or skip a calibration, your tool will not operate at peak performance.

How long does calibration take?

Express Assembly’s standard turnaround is one day after we receive the tool. Get more information about our torque screwdriver calibration program


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