How to Reduce Human Error and Improve Angle Accuracy During the Tightening Process
Across the market, the adoption of production automation increases year by year. This trend is driven not only by labor costs and efficiency demands; in some precision-sensitive workstations, automation has become the primary method to avoid human influence and determine batch stability and product qualification. However, not all workstations can achieve standardized assembly! During manual tightening with handheld tools, the tool's movement can significantly affect the output angle—especially when angle is a key parameter in the tightening strategy.
Critical Connections
For critical connections, screw counting is necessary. In addition to controlling torque variables, additional monitoring variables are required. Typically, we monitor the angle, which helps identify situations where torque meets the standard but actual clamping force does not.
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In scenarios involving self-tapping bolts or high bolt utilization, strict requirements for clamping force make angle-based control strategies essential. This approach prevents workpiece damage or bolt failure, avoiding direct economic losses.
In the above requirements, both angle and torque variables are equally important. These can be relatively easily achieved through automated production lines equipped with sensor-based tools or tightening spindles. However, for workstations with complex, variable, or non-replicable tightening angles, manual assembly remains necessary. Examples include the fixation of automotive seat assemblies to the chassis, rear seatbelt buckles, and other similar workstations. The question then arises: how can we ensure high-precision requirements during manual assembly and correct the human-induced angular errors caused by handheld tightening screwdrivers?
Two solutions can be adopted: reaction fixtures or tightening tools integrated with gyroscopes.
Reaction Fixtures
In practice, both the reaction force from the tool and the operator's stance can cause the tool to rotate at a certain angle. While we monitor/control the clamping force through angle measurement, the angle itself may already have a significant error. A common method to prevent tool movement is to fix the tool in place—this is known as a reaction fixture, including:
Using the methods above, almost all human-induced angle errors encountered in conventional tightening can be effectively resolved.