Pre Load in a Fastener explained in the simplest way possible - Pre-Load = Clamping Force
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- เผยแพร่เมื่อ 23 ก.พ. 2023
- The term Pre-load is commonly used in the Engineering Sector but the meaning of it is not often fully understood. This video sets out to visually explain this in a simple way for everyone.
Once it is understood the importance of maintaining the pre-load for certain applications becomes apparent and that is where our other videos might be worth watching too.
The other videos explain the ways of testing bolt securing devices for their performance in maintaining the load using the Junker Test Method to DIN 25201.
They also show how some devices are only to be used as "Loss Prevention Devices" where it might be important a nut does not fall off the fastener but it is not that critical that it maintains the load in it. Such as in a food plant where the bolted joint might not have major loading but you can not allow for a loose part to fall into production for example.
You can see the variances in performance and how some more traditional devices are clearly not up to the task for the more Critical bolted joints that are subjected to joint movement or vibration.
We aim to assist people with any Fasteners problems so please visit our website and get in touch if you need support.
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Thanks for eXplaining the "wedge-washers" in detail. I was afraid the video would just "cut off" before I knew anything about them
I agree.. good washers can extend the life of a joint and maintain adequate fastening loads, as with variations in temperature steel bolts can slowly unload due to permanent stretch. They also help prevent a bolt from unscrewing if it becomes load deformed. Note; this is why old bolts are not to be re-used in the application that they are taken out of, such as car engine head bolts and studs. In the USA you can access these at McMaster, MSC Industrial Supply and other industrial outlets.
wonderful video folks!
We were looking at a bolt for a bridge the WHOLE TIME!
In the absence of a wedge washer, use loctite. If you're a farmer, just damage the thread below the nut with a punch.
As others mentioned, they show the addition of wedge washers but no explanation to further brilliant design. I have used them in many applications during my maintenance career and they are definitely the best solution to lock washer use.
".....then Wedge-Washer is the perfect solution"..... he says. Okay, HOW I ask. They just end the video with that statement and nothing to back up that statement.
Go to their previous video.
This tells us more about screws borrowed from aunt.
pretty deep lore
Alright, send me some wedge washers. I would like to include in my next round of testing.
untrue, if the bolt is preloaded pull force can be significantly larger than bolt preload. The bolt usually takes 10-20% of the pull force if preloaded. This is to do with clamped material stiffness which is times larger than the bolt stiffness.
one thing he didn't say . once you preload a bolt any force bellow the preload does NOT add to the tension in the bolt.
What do you mean,
Can you please explain your sentence more easily?
@@MEDDY-c1d
Imagine you have a piece of pipe and a rubber band that goes through it. On each end of the rubber band you have a washer or a ball or anything that won't fit inside the pipe. The rubber band is shorter than the pipe, so the balls or washers at the end of the pipe are constantly forced together, against the edges of the pipe. Now, imagine pulling any of the two balls or washers away from the edge of the pipe. As you start pulling, the force will increase, before the ball or washer finally starts moving away from the edge of the pipe, as you exceed the preload tension, but until that happens, the force in the rubber band itself (which represents the screw) stays the same. So, you can pull or hang a load from that ball or washer and as long as the force of the load doesn't exceed the preload force (the one that's already present in the rubber band or a screw), the force inside the rubber band or a screw will remain the same and the parts will stay pressed together. If you have 1 ton of preload, you can pull with up to 1 ton of force, before the fastener will stretch further, the force inside the fastener will increase beyond that 1 ton, and a gap will start forming between the clamped parts, but if you pull with half a ton, the force inside the screw will remain at 1 ton - the only thing that will change is the clamping force, which will decrease by the amount that you're loading the fastener with. So, if you pull with 1 ton, you'll have 0 clamping pressure left.
this is not true. the Bolt and the clamped members have their own corresponding stiffnesses and the stiffness constant of each will determine the proportion of load taken by the bolt vs by the members.
It does effect the tension, what you're saying is you put some force somewhere and it doesn't effect the system that's perpectual system
Just watched a video of (i presume an engineer) explain this concept quite ambiguous
excellente
1:05 надпись - прелоад, что это?
pretty cool ad
Wow..
Never seen a washer like that. Where is this from?
Called a nordlock washer.
Preload is same as proof load?
No. a proof load is a load that is as much as twice the rated pre-load specification before deformation and load degradation is observable under the specified loading requirement
It's more like an elastic cord than a spring.
Metric bolts are classed. Not graded.
'
better use lock nylon metalnuts
Wedge Washer more like "Lock Washer"!
No.
"Simple explaination"
Explanation.
Are people's comprehension skill that bad now? It minimises the effect of vibration and subsequently reduces the likelihood of them loosening.
We're so fd
*EVERY* video with synthesized voice gets an _automatic thumbs down!_ 👎🏻
fake
a