Fastening Technology – Precise Testing of Bolt and Nut Assemblies

Bolted joints are among the oldest and most essential elements in mechanical engineering. Manufacturing screws and nuts is one task – testing their mechanical performance is another.

The TesT Series 205 testing machines are specifically designed for rotational testing of bolt and nut assemblies, accurately measuring the key physical parameters preload force, tightening torque, and rotation angle. Since preload force cannot be directly measured during industrial assembly, the 205 machines are used to determine the relationship between preload and the measurable quantities under controlled laboratory conditions. 

TesT provides testing systems for bolt sizes from M3 to M80 for coefficient of friction determination, test rigs for temperature-dependent tests up to 150 °C, and vibration test stands according to DIN 65151 (Junker test) for evaluating loosening behavior. Additionally, four-component sensors enable direct measurement of preload force, total torque, under-head torque, and thread torque – without relying on calculated values.

The result: precise, reproducible test data for the design, quality assurance, and optimization of modern fastening systems.