Modular friction test rig for measuring torque and tension in threaded fasteners

Abstract: This report describes the development of a modular friction test rig for threaded fasteners. This device can measure the shank torque and the clamp force during the tightening of threaded bolts, with a size of M3-M14 and clamp length of 30-160mm. The design allows the use of several load and torque cells and the range is up to 100kN clamp load and 200Nm applied torque. The test rig will be used for research purposes by Atlas Copco to determine the frictional characteristics in tightening and will allow the experiments on bolts with several materials, coatings and surface finishes. This report concludes to a design proposal evaluated with analytical methods and a prototype 3D model that demonstrate the working principle of the test rig. The measurements are taken from custom-made sensors that are developed with high standards, are easily interchangeable and can be calibrated individually. In addition, a device is developed to allow the user to change the stiffness of the joint. Finally, a future recommendation is made to allow the measurement of the under-head torque. This proposal is a breakthrough compared to other test rigs, and will assist in verifying the friction measurements and having high precision results.