Self-tightening nut that provides tight fastening with a unique screw thread
akihabaranews.com
akihabaranews.com
It's certainly interesting that they're managing to keep the tightness up without resorting to any truly strange designs.
However as some have noted, cost will keep it from being adopted. Let's face it, fastening is the last thing considered in a project and the last thing bought. Even for large projects it's at most a few percent of budget and people are desperate to limit it's cost as much as possible.
Also, truly there's no need for a product like this unless the stress on the bolt, nut and what's being fastened have to be manage just perfectly. Otherwise the simplest solution to relaxation is just tightening more. Then it relaxes to an appropriate stress.
Almost all bolts in the world are under-tightened. Greater analysis of the joint you're tightening rather than a fancier nut will pay off many more dividends.
Let me clarify. I applaud the effort, fastening needs research and development badly, but this is no miracle nut, rather it's a specialized application.
Well personally I know a few scenarios were the nut has keep steady when its hard to do. But for that case I prefer two nuts stacked on top of each other.
You learn something new everyday.
[1] https://www.google.com/search?q=nylock+nut&espv=2&source=lnm...
But think about the bolts and nuts that hold the exhaust system to a car engine. Temperatures are going to be very high and nylon wouldn't withstand those temperatures. Things like that.
[1] http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/1990000...
Engine blocks.
Further engine blocks are pretty cheap, all things considered. Turbines have tighter engineering constraints and wider price constraints so I would look there before looking at reciprocating ICEs.
Yes the bolts must be torqued properly but that has more to do with ensuring that even pressure is applied across a huge gasket face than anything to do with the bolts self-loosening. If the heads on an engine were steel and much thicker you could do the same job with a couple of bolts instead of a dozen.
If an auto manufacturer was enterprising they could probably move some of the oil passages away from the coolant and combustion (which by their nature need to be close to one another) and they could make cavities for o-rings and seal the oil from the coolant a lot more effectively. But the failure rate for head gaskets is fairly low already and that would be adding a fair amount of cost and fiddly-ness to a not-that-big problem. When I say "fairly low" what I mean is that it might comprise 10% of engine failures but engine failures are already pretty rare, so 10% of 1% isn't all that big of a deal. Those are made-up numbers, btw, so don't crucify me if they're wrong.
Ensuring that even pressure continues to be applied cross a huge gasket face is somewhat helped if the nuts do not become loose.
http://olybrake.com/pdf/fel_pro_torque_specs_guide.pdf
Most of the plain old torque specs in that brochure are at least 60 ft-lbs and there are some upwards of 100ft-lbs. That is no joke. If the bolt is a grade 5, 5/8" nominal diameter tightened to 57 ft-lbs that's over 4 tons of clamp force. At 82 ft-lbs it's just shy of 6 tons. At 113 ft-lbs it's over 7 tons. That's PER BOLT.
https://www.fastenal.com/content/feds/pdf/Torque-Tension%20C...
Applying 60 or 80 or 100 ft-lbs of torque to a bolt will cause huge amounts of clamp force which highly motivates the bolt not to wiggle loose. A lot of the problems where bolts (or nuts) self-loosen in high vibration environments is due to a torque spec for a sub-maximal amount of clamp force. If you're making machine tools and you need to tension ball-screw bearings (an application mentioned in the video) you can't torque the shit out of things because of the bearing pre-load needing to be a substantial but not insane level. A few hundred pounds of preload (a reasonable range for CNC spindles or ball-screws) can be achieved with only a few foot-pounds of torque; it's exactly what the machine needs but not enough for the bolt to keep itself from working loose.
Engine heads and head gaskets are complicated because you have to apply a lot of clamp force very evenly over a large area. The bolts are more than good enough for this, I've got several friends who are mechanics and none of them has heard of a head bolt that's loosened itself. The problem is that manufacturers often use "inferior" (less expensive) grades of head gaskets because the failure rate is already quite good.
EDIT: I don't disagree that needing to maintain even pressure is necessary (it is), nor do I disagree that nuts which can't wiggle loose doesn't help mitigate the problem. What I'm trying to say is that the failures which do happen are caused by the weakest link, and that in many cases the weakest link these days isn't the bolts or the heads or the block or whatever, but the gasket itself.
At least, that's what i want them to do :P
http://www.technologystudent.com/joints/comnut1.htm
Of course, this adds some extra overhead when disassembling the part, but the nut won't come loose unless there's a different problem (e.g. corrosion).
This is incredibly true IME. When I was working at Xerox, they were in the process of switching to vastly inferior fasteners just to save a couple bucks per $500K machine.
Not the biggest market, sure, but it's a market where you could very plausibly sell a single fastener for ten-plus dollars with the right marketing.
I doubt I'd buy a 10 dollar but either but if you marketed it as aero I know some who would ;)
I wonder how all the patents and trademarks collide vs the "semi-well known" Hytorc nut, which is basically the same idea but with an integral washer at the base. Hytorc's are strange little differentially threaded nuts, so instead of the tension coming from a spring half moon shape, the tension comes from the secondary fine threading. They're kind of expensive, outta my price league, so I'm guessing this new nut is going to be out of my league.
Where I do see it making an impact, is "every gram counts" and if you took every washer and lockwasher off an instrument panel and replaced the nuts with these, you might save a small but measurable mass, which translates directly into a small but measurable increase in payload or range or lower fuel consumption or performance. Even on a small plane this might be a pound or two, but imagine a giant jetliner and it adds up to a respectable mass, probably financially a good idea... if its ever aerospace rated.
Note that there's kind of big gap between being listed for sale on a foreign web page with no documentation at all and no specs or datasheets or certs, and being COTS at a place like "aircraft spruce and specialties". For laughs I went there and the price to beat for certified aerospace grade locknuts is like 48 cents a piece, so I donno if this new gadget can compete in the aerospace market at the typical 100x price markup... I mean sure saving weight and fuel is cool, but not if each aircraft certified nut costs $500.
http://www.ztec-izushi.co.jp/english/
I think this is the product on Alibaba:
http://jp1009830113.trustpass.alibaba.com/product/128852485-...
It's not that unusual an idea. Pipe threads and fittings have both sides of the thread in contact, to prevent leaks. Look up "National Pipe Thread". There are lots of self-locking thread designs, such as Wide-Lock (http://www.threadcheck.com/self-locking-thread/), Spiral-Lock (http://www.youtube.com/watch?v=0hCgeimks94).
A bolt with nut is supposed to work like a kind of high-tension spring pulling the pieces being fastened together. For large safety critical projects there is a technology to directly measure the tension of the bolt so that you know you have tightened the nut enough: http://www.checkline.com/product/TI-MINIMAX
This is better than a torque spec (where you don't know the friction exactly, so the bolt tension is an estimate).
Where the holds because of the constant pulling and tension unscrew themselves form the wall and start to rotate, until some unlucky bastard goes for it...
It's definitely safer than a plain nut, agreed, but is it noticeably safer than any of the other thread locking solutions out there?
It seems there's very little money in fixing spun holds.
Gyms clearly don't use loctite, but I think it's just because the problem doesn't warrant the slight increase in mess and hassle.
(fun to read the nuclear engineering forum..)
By the way, you can use two nuts to prevent loosening:
http://en.wikipedia.org/wiki/Nut_%28hardware%29#Use_of_two_n...
this could be cheaper than a much more expensive single nut. This article section explains how vibration causes loosening. The second nut ensures that the first nut stays in firm contact with the bolt threads even during moments when the pre-load is momentarily lost due to vibration, and so cannot rotate loose.
There's one thing that might be problematic with this design. The nut has a threaded c-shape insert. Due to the threading, when it is in the "wedged" position, it doesn't just have to close the gap between the tips of the "C" (let's suppose that this deformation is in the horizontal plane), it also has to deform vertically due to the threading.
This vertical plus horizontal deformation must be either harsh on the material, require a relatively small amount of "wedge" (reducing the usefulness), or have a complex initial shape in anticipation of this type of deformation.
Stage 8 and safety wire seem simpler and they should offer more predictable torque for critical applications. Hoping to see some comparisons to existing solutions and failure analysis.