As a structural engineer, when we need proper pre-tension in a bolted connection, where mistakes would be catastrophic, we use tensioning tools, otherwise we torque it.
For most general engineering purposes, canvassing for the use of tensioning systems is a waste of time. More advance is achieved by educating craft/technician level users to make any useful effort to tighten threaded fasteners (usually a torque wrench, please) and by educating engineers to design viable bolted joints. We have only 17 years left until the 200th anniversary of Joseph Whitworth's standardised threaded fastener and I think 200 years is more than enough time to have spent learning how to use it. 🤔
@@PhuongLe-gg4ge In aviation and automotive production there are still many applications where threaded fasteners are used for convenience and maintainability when other fastening methods might be functionally better. Many such applications are not very effective and can be difficult to maintain. An ideal threaded fastener joint uses a LONG bolt or stud so that there is plenty of stretch and this makes the joint very effective and resilient. It can never be as simple as 'heavy duty' (do you mean ISO 8.8/SAE 5?) need torque or tensioning. In automotive, many engine bolts are designed to fine tolerances of clamping and require highly reliable and somtimes complex tightening methods. This is increasingly true for important chassis components. Torque wrenches are rejected by many because of the wide tolerances of this method and the twist put into the saft of the fastener by applying a torque. However, torque wrenches simple to use, are far better than nothing, and can be superior to tensioning methods done badly!
Princuple Stress in the torqued bolt is also higher for a given pre load. Torque shear plus bolt tension stress as a pose to tensile only when employing bolt pre tension. Many thanks for the video
what about the other variables in regards to the +/- factor? Just curious where the percentages are coming from. does thread type play into it as well?
if you lubricate you change the preload of the bolt, for the same preload you have to use a lower torque, and you still have the 30% of error for that.
