Torque Figures Are Quoted At The Tool, Not At The Screw

Torque numbers are the headline specification for driving and tightening tools, and they describe the tool rather than the job. What arrives at the fastener is what remains after friction has taken its share.

Torque is a twisting effort, not a force

Torque is the product of a force and the distance from the axis at which it acts, which is why a longer handle produces more of it for the same effort.

It says nothing about speed or about how long the effort can be sustained, so a high figure can coexist with a tool that stalls quickly under continuous load.

Power is torque combined with rotational speed, which is why two tools quoting the same torque can complete a task in very different times.

Most applied torque is consumed by friction

When tightening a threaded fastener, only a small fraction of the applied torque becomes clamping force, with the remainder lost to friction under the head and in the threads.

The proportion depends on surface finish, plating, lubrication and cleanliness, so the same torque setting produces widely varying clamp loads on nominally identical joints.

This is the reason critical assemblies specify a condition as well as a value, and why applying a dry specification to a lubricated fastener overloads it substantially.

Rated figures come from favourable measurements

Manufacturers measure output under a defined test, often with a fresh battery, a rigid load and a short measurement period that avoids heat build-up.

Maximum figures may be instantaneous peaks rather than values the tool can sustain, particularly for impact mechanisms that deliver energy in blows rather than continuously.

The distinction matters because a fastener responds to sustained torque, while a peak reading records a moment that may have lasted a fraction of a second.

Impact and continuous torque are different products

An impact mechanism stores energy in a rotating mass and releases it as a hammer blow, which produces very high momentary torque with little reaction felt by the user.

A continuous drive applies steady torque, and everything it applies to the fastener is also applied to the user's wrist, which limits what is usable in practice.

Comparing the two on a single number is therefore misleading, since the impact figure describes a mechanism the other tool does not have.

Measuring is more reliable than setting

A torque wrench applies a controlled value, but its accuracy depends on calibration, on the smoothness of the pull and on it being stored unloaded.

Angle-based tightening sidesteps the friction problem entirely, snugging the joint and then turning a specified further amount, since rotation relates directly to stretch.

Where a specification gives both a torque and an angle, the torque is establishing a starting condition and the angle is doing the actual work.