Friction Factors - Fastening Theory Part 2
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- Опубликовано: 16 мар 2017
- www.flexibleassembly.com/
In this episode of Fastening Theory we cover some of the friction factors that effect tightening such as part tolerance, alignment, material, lubricant, fastener type, materials and more. 
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Another excellent video.
Thank you again! If you have any ideas for a part 4 let us know!
Thank you for this video
Well explained
Great, basic information. I really wish you had gone more into information about what happens to the fastener as tension is applied, like how the bolt is elongated, changing the tolerance of the inclined plane, while creating maximum clamping pressure, and how further tension or excess torque leads to failure. I thought that would be discussed, given the graph that was shown at the beginning of the part 1. In any case, this is good info, but is definitely missing that key part.
Thank you! You bring up excellent points, we should do a follow-up on this video including that information.
Flexible Assembly Systems Inc That sounds great! Still, though, I've already shared this video with someone. Looking forward to future ones!
So far great, Looking forward to Part 3, explaining the queries raised byTravis already!!
Great video, how did you do the animations?
Thank you. I used 3D software similar to Blender to animate the video, then cut it all together in Adobe Premiere.
Hey what is dynamic torque range, static torque range on a bolt or nut..?
Can u make videos on fasters selection in design?
Which is the better method of measuring residual torque, Re-tightening Torque method or loosening torque and why?
Assuming no glue or loctite was used the best method for auditing residual torque is the breakaway strategy. Using a torque wrench equipped with a transducer (and gyroscope for added accuracy) the operator can use a residual torque audit strategy to slowly apply fastening torque to the bolt until it rotates. Most torque audit strategies use this method as it doesn't require re-tightening the bolt. The downside to this strategy is that in doing a reading you are risking over-torquing the bolt. It's recommended to very slightly under-torque the bolt originally by the amount which you have determined through testing that it will over-torque during the audit process.
If over-tightening is a concern, then a safer bet is to use the loosening strategy, however this has the downside of now having to re-tighten the bolt after you have confirmed what the residual torque was.
A third method would be the loosening-tightening strategy. The operator would use a wrench with a gyroscope to loosen the bolt by a certain degree (say 10 degrees), then tighten the bolt by the same amount they loosened it (10 degrees) and measure the peak torque which was recorded. If a gyro tool isn't available then a mark can be made on the bolt to ensure it has been tightened back to the same angle.
In all cases factors such as rust in the bolt, tolerances of the parts and operator influence can effect repeat-ability. Wrenches that include a gyroscope and transducer can use algorithms to negate the effects of operator error. Either way it is impossible to measure the residual torque in a joint without actively effecting how much clamp force is applied during the test. Hope this helps!
How we can check, how much torque applied in fasteners with the help of Digital Torque meter.
Video please....
Hello! We have a entire playlist of different torque testing tools. I suggest checking out the ST Wrench from Atlas Copco. ruclips.net/p/PLXtz_Anwq59iX5p9KaVZ-y7s3QWRi9z7A
You dont talk about what effect threadpitch has on tranforming torque to clamping force. What happens when the pitch is changed either way?
That is a good point. I didn't do much research into that particular question. A smaller thread pitch increases the surface area on a bolt, which would also increase the friction within the bolted assembly where the bolt interfaces with the nut. My guess is that a smaller pitch requires more force to overcome the extra friction. Definitely a good topic for another video!
Cool
Where's part 3?
Part 3 is in the making, it should be finished soon!