Due to the washer style can be used with a wide range of fasteners. The most common type, in my experience, due to the ease of use, has a little bit of colored goo inside the arched cells. The goo squirts out when the specified torque is reached.
That being said, there are a lot of approaches to this same problem. Another common technique is breakaway bolts that are driven with a piece that snaps away when a certain torque is reached: https://youtu.be/lrCoi3gaLfU
Smartbolts seem to be useful in applications where there is an expectation the bolts will loosen over time/the maintenance lifetime, reducing/easing inspection time.
Installing to a known torque and painting a line on the fastener is a lot less expensive, which becomes important when your project has potentially tens of thousands of key fasteners, like a bridge.
But for something like an MRI machine where there’s fewer fasteners and higher stakes - would make a lot of sense to use Smartbolt I think.
A problem with installation is that torque is only a proxy for tension. Torque alone is not incredibly accurate, so there are a lot of cases that could benefit from an easier way to accurately indicate tension than by externally measuring the stretch of the bolt (which often is not an option)
True, but this caveat is generally pre-empted in design phase through safety factor principles - multiply certain design parameters by a coefficient greater than 1 to account for the inaccuracy in things like torque-tension correlation.
I’m not getting your point here, won’t there always be inherent trade offs?
If you scale the specified torque, you risk over-tensioning.
If you scale the dimensions of the fastener, that has lots of consequences.
Is there some safety factor here you can add “for free” that I’m not seeing?
Otherwise, why is it that you “generally” pre-empt this caveat with safety factor versus coming up with a more reliable way to achieve the right tension?
The general idea is that proper bolt installation is a solved problem…at least in so far as ordinary industrial/commercial/construction applications are concerned. There’s an informed experienced trade base, a well established supply chain, and sound engineering practices already.
To put it another way, the right tension includes a safety factor. And engineering practice specifies testing and inspection and proven materials.
That safety factor and testing and inspection has costs associated with it.
Basically, it is a "solved problem" by designing things stronger than they have to be, and spending more on testing and inspection than necessary.
I'm sure the cases where these things are economical are fairly few, at least today, but if everyone took your attitude no progress would happen at all.
Safety factors; testing; and inspection are engineering.
The Smartbolt doesn't eliminate engineering.
More importantly, safety factors; testing; and inspection are progress. We have robust assemblies built first time based on rational analysis and formal processes. We have sky scrapers, suspension bridges, and space telescopes.
Obviously it doesn't eliminate all engineering. What it could do, though, is reduce costs. The idea is you could potentially achieve the same level of safety with less material or less testing.
Those things are progress in a sense, sure, but...
It's as if someone finds a way to make an alloy less prone to metal fatigue, and you just say "but you can use thicker metal, and test more." Sure, but.... well I don't see the point explaining this further to you, but I assume people reading this that don't see everything in black and white already understand.
Does that give you the ability to have nuanced, big-picture, long-term view thinking?
You might as well argue that someone who works in a bank must understand macro-economics, or that someone in the military must have an excellent grasp of foreign policy.
You are steeped in the status quo. Your thinking on this is expected.
There's a fantastic set of two textbooks covering bolted joint design by John H. Bickford. One for gasketed assemblies and another for non-gasketed assemblies, if you want to really _really_ dive deep into it.
At the end of the day you get the final clamping force by multiplying a bunch of modification factors together that have been empirically measured and the bolting procedure has been verified. When you step outside any of the parameters you've verified in the past, you have to substantiate the math with experimental proof. The size of the fastener, fastener style (e.g., stud vs. bolt), fastener length, thread pitch, torquing method, presence of a washer, presence and type of lubricant, fastener material, base part material, and bolt arrangement ALL play into the final bolt assembly procedure. A lot of these are well-known and published.
Nobody is out there on assemblies like this just slinging unsubstantiated numbers around, at least if they're doing their due diligence.
In case anyone else needs to look this up, torque-plus-angle means seating the threaded fastener to a base torque, and achieving the target tension from there by further turning the fastener a specified angle. So super duper simple and something that many of us have done instinctively or from instructions, now we know there is a term for this general technique. Cf https://dannysengineportal.com/torque-specification-torque-t...
Yeah, a quality torque wrench isn't cheap (particularly the kind you find in fixed installations like auto repair shops and factories) but there's got to be some crossover when you are buying enough bolts that you're better spending money on tools that are more idiot proof.
I install automated and semi-automated equipment in factories, sometimes including threaded fasteners, and the overwhelming majority of QC issues I observe (both on the devices being manufactured and on the mechanical equipment I'm delivering and writing code for) are not inaccuracies in torque or clamping load, but instead, failure to torque a bolt at all. The cycle was started but someone hit the E-stop mid cycle, and the fasteners were barely finger tight but you can't tell by looking at it.
A torque wrench is better than a Smartbolt once it's put on the fastener, but the Smartbolt can be measured just by looking at it.
An HN company does a similar thing with RFID tags for grease zerks:
Again, it's not so much about measuring that the precisely right amount of grease was dispensed, but that every one of the 37 grease points was at least near the tip of the gun once every 30 days for the life of the equipment; the operator didn't forget about that one zerk that's hard to see and grease only 36 zerks for 5 years...
A problem with many torque wrenches is that they click (or beep) when the set torque is reached, but they do not prevent tightening beyond that, nor do they have any way to indicate how much overtightened the fastener might be. It seems to me that these bolts have the same issue.
Ever wonder why the tire shop has tightened your wheel lug nuts so tight that you can't get them off with the hand wrench when you need to change a tire? They spin them on with a pneumatic impact wrench, and then "check" the torque with a torque wrench. Of course it clicks, because the nuts are already way too tight.
Powered torque wrenches like Milwaulkee's (designed for electricians) and assembly line fastener drivers absolutely stop at the proper torque.
If you think dealership/tire shop/corner shop garage techs touch a torque wrench for lug nuts, you're dreaming. They blast each nut on with the gun and walk away.
Techs never are incentivized to get everything done as fast as possible because they're paid by book rate, and there's zero disincentive for not doing it properly.
Torque sticks were an attempt to address the problem but most techs can't even be bothered with those.
Proper torque for lug nuts is multi-step anyway. Star pattern partial tightening, with the wheel placed correctly on the hub if it doesn't have a concentric ring - then full tightening, then re-checking after the vehicle has been driven for a few minutes, because of fretting between the wheel, rotor, and hub surfaces...even if you've carefully prepped the surfaces, which again, no automotive tech does.
That explains a lot. Had a tire shop tighten the bolts on my old car so extremely tight that the threading on the bolts were broken. Every time I changed the tires after that I had to use a wrench with a looong bar attached to loosen the bolts (In Norwegian we call this a “latmannsarm which directly translates to lazy man arm, not sure what the English word would be). No matter how much grease or how much care I took to not tighten too hard the bolts were stuck next season. Glad the car is sold and not my problem anymore.
(I could of course have bought new bolts, but I always forgot about it after spending 2 hours changing the tires …)
Not mentioned on that page, but you can make one out of two ordinary wrenches, which is both practical and may impress your friends! All I found online describing this was a video: https://youtu.be/5DShRItYxLA
Adding on to that, tensioning bolts using torque is convenient and inexpensive but not very accurate at all. Some data reproduced in Shigley's Mechanical Engineering Design showed a +/- 30% variation in tension for properly torqued bolts, if my memory is correct.
Emphasis on properly torqued: in the field threads or bolt heads might be dirty, or torque wrenches might be out of calibration, adding even more uncertainty.
Torquing to a known torque and painting marks is fine...except there's no guarantee the clamp load hasn't changed due to all the mating surfaces wearing.
There's also too many variables in the real world if the application is critical enough. Clamp load changes with how many times the fasteners have been assembled due to the threads getting polished, how clean and dry the fasteners are, etc.
Ah; so that's what those are for. I've seen them on lorry wheels, but never got around to formulating a sensible query for a search engine. These becoming commonplace seems like a recent thing (as in last decade or so).
I'm not an ME or anything, but it would seem washers attest to pressure (tension) at some point in time (when the nut was tightened -unless the washer is "springy", which I doubt as it seems it simply yields at some point), whereas smartbolts attest to the tension when you look at them --so during maintenance and not only during installation, so from that PoV, they are more useful (informative).
That’s true, but you can have a qualified inspector mark bolts with goo with a paint line that straddles to the fastening surface. Then you can just inspect the paint line for movement, which gets you most of the same functionality at significantly lower cost.
Of course, that requires a trustworthy inspector, which is one application where smartbolts become useful, if you don’t have a trustworthy inspector available at install time. But many projects that have importantly torqued fasteners (bridges, buildings, rollercoasters) have certified inspectors anyway… which is why smartbolts are a niche product I think.
Speaking to the trust problem - if you trust the operator of the torquing install device, you don’t need fancy torque indication at all, just mark the paint line at install. That is the most cost effective.
That line is fine if the bolt winding itself loose is your only failure scenario, but some might have others as well. What of they clamp a part that can subtly deform in certain exceptional situations? Then you could have a bolt with zero tension that is still perfectly aligned with the marker line from when it was properly torqued.
What I find somewhat surprising is that they make the "ok" indication black. The cry for attention state in red seems nicely intuitive at first glance, but given the market they serve they should be far more concerned with false negatives than with false positives and I imagine that it would be very easy for dirt or bad lighting to make a red indicator remain unnoticed in an inspection. Perhaps the color choice is an inherent property of the chemistry involved?
It's not chemical. It's mechanical. It basically covers the red with a black liquid when it's good. A different color probably wouldn't cover the red as well. The bolt is basically hollow to do this.
The paint line is the most common method I have seen. I was an inspector and for fasteners in a critical load path we would use an ultrasound machine to measure the length of the bolt (these were installed in flange like connections). We would measure them when first installed and compare measurements after that piece of equipment was used.
For really critical components we would disassemble them after every use and would perform multiple tests on each piece including fasteners.
Totally agree. And two cents to add. The so called smart bolt adds movable parts in side a part supposed to be inertia and at the same time might compromise the strength in comparison with ones with the same profile and body material. And when faulty, it actually more dangerous than ordinary ones: now your torque wrench and the bolt gives different readings, which one to trust?
There's no moving parts. The bolt is hollow with a pin projecting from the tip of the bolt back to the head. When put under tension, the outside of the Bolt stretches, but the inside pin doesn't. It's not as strong as a solid bolt of the same size and material. But that's something you engineer around.
Yes, that seems like a cheaper option; however, I think when you have constant stresses over time, bolts can stretch or simply parts can wear over time and a paint score or even a frozen nut won't reveal lessened tension. Though maybe in this case the issue would have become a concern way before the bolts start to indicate a problem?
Interestingly that has kind of moved upstream to a design phase consideration in modern times due to the incredible depth of understanding we have about materials. Structures can be designed such that their expected loading will not stress fasteners beyond their ‘yield strength’, which is well characterized.
Maybe the following has been designed out; however, I've on occasion seen the following wear pattern which compromises the initial strength of a fastener (usually due to friction over time):
First, I love the plain text diagram! (Edit: not fatigue) This failure should be predictable during the design phase and that fastener is either wrongly specified or should have a recommended number of cycles after which it should be inspected and replaced if found to be out of specification.
Of course, many items in our built world do not receive the same level of design scrutiny as I would wish, nor the maintenance regime…
Unless I'm misunderstanding the diagram, it does not look like fatigue at all but rather yielding from shear loading.
The definition of fatigue is a small crack (in fact microscopic in the beginning) that grows through the application of cyclical loading (typically about 10k cycles is the lower bound for high cycle fatigue, which does not involve macro yielding).
Thus a fatigue failure would look like a fully ruptured part , usually with two distinct zones of the fracture face: one smooth zone from crack growth ( sometimes with characteristic "beach marks") and the final sudden rupture which is usually rough.
What I was trying to convey, which I didn’t do well in the diagram, was you have a bolt holding two plates together or a splice, and you have wear on the bolt shank -not necessarily shearing.
Out of curiosity, on a somewhat related topic, have you tried nord-lock washers [1] in any of your applications? We looked at them for a small work boat we designed and built, but they were a bit pricey and it was just a prototype, so we ended up just using a dab of lock tight to avoid vibration. Was always curious to find someone who had practical experience with these things. I may use them on an upcoming autonomous boat project where there's nobody around to do rounds and tighten loose bolts that have shaken loose unexpectedly.
When I worked on railway vehicles (bogies for passengers vehicles, more accurately), Nord locks (or equivalent clones) were standard on all structural joints.
Especially on a prototype I'd recommend them. Prototypes are really expensive, a complete supply of Nord locks for your project is probably less than a single one-off CNC part.
Note that Nord locks are specced to be single use. Not that I've never reused some on prototypes, but, well, I'd never do it on a life-critical joint that is meant to be taken apart often.
I have used Nord-lock washers, they are demonstrated to be one of, if not the most effective thread locking washer devices under heavy vibration, but as you say they are quite pricey. I would certainly recommend them if you have the time/cost budget, especially for something like an autonomous boat where vibration is expected and routine inspection is challenging or impossible.
When I’ve used them, it’s been for critical fasteners where ease of assembly was important, and could not be effectively decoupled from vibration, and where our recommended inspection/maintenance cycle was not guaranteed.
You might also consider something like a pinned castle nut, or safety wire, etc. These are not as simple to specify or install but more cost effective. Also, I’ve seen safety wire used as a conductive link to detect failure in a remote application.
> When I’ve used them, it’s been for critical fasteners where ease of assembly was important, and could not be effectively decoupled from vibration, and where our recommended inspection/maintenance cycle was not guaranteed.
Taken to heart - sincerely appreciate the insight!
"I have used Nord-lock washers, they are demonstrated to be one of the most effective thread locking devices under heavy vibration, but as you say they are quite pricey."
Which is odd, given their simplicity and ease of manufacture, etc.
NordLocks are excellent - I was told about them by a very experienced racecar engineer who helped me work on my racecars - he couldn't say enough good about them, and recommended them for anything close to critical importance (or that you just wanted to stay fastened). Another engineer friend had a biz providing racecar component kits (think brakes, suspension, etc.), and also enthusiastically all his kits with NordLocks. I've had less experience but never seem them fail. Good stuff
The thing about torques is that they’re often written into safety standards, and safety standards often have to explicitly detail how critical values are measured. So until fancy bolts are recognised in the current standards as best practice for confirming correct torquing (are they? I dunno), it’s gonna be really hard to get them into production.
The bolts I worry most about coming off are this in my car wheels. I’m not sure I could use washers there and they are recessed in the rim so the gap isn’t inspectable. That seems to be the biggest benefit of these, that the only part of a bolt that is always inspectable/servicable is the top and that’s where the indication is?
Just curious = how do these SmartBolts handle under full tension load AND fire conditions...
You have effectively drilled out the core of a bolt and replaced it with "goo" and you are using this as an indicator of the health of that fastening node?
So what if you burn out the goo? What if you get side/compression damage on the device -- what does the thing do when you over-tight/strip?
isnt a "goo core" less structurally strong than a solid bolt? Is a bolt tightened to a setting using a SmartBolt vs a regular bolt with tension wrench going to manage the same loads or not?
> isnt a "goo core" less structurally strong than a solid bolt?
Yes, the oil used in the centre offers zero structural support.
> Is a bolt tightened to a setting using a SmartBolt vs a regular bolt with tension wrench going to manage the same loads or not?
Depends on what the original bolt is made out of, and what the SmartBolt is made out of. Two different bolts are always going to have different properties, it up to the designer to match the size and strength of the bolt to their application. You would need to validate you design with SmartBolts to ensure they have the properties demanded by your application, you wouldn’t just swap normal bolts for SmartBolts without making sure SmartBolts were at least as strong as the original bolts.
At Boeing, I learned that bolts should be lubricated before torquing them in order to ensure an accurate torque. I initially thought wouldn't the lubrication allow the bolt to unwind itself? Surprisingly, no.
Since then, on my car, I always put a bit of grease on a bolt beforehand. It keeps the water out, preventing the bolt from rusting itself together. It makes for an accurate torque. I've never had one unscrew itself, and I can always get the lug nuts off!
Of course, you still need to use lock washers. For critical bolts, use a cotter pin or a safety wire.
> lubricating the threads can cause over-tensioning of the bolt if you torque it to the (typically) unlubricated torque spec
This is correct. My main exposure to it was from the ASME's boiler and pressure vessel post construction code - ASME BPVC PCC-1 - which is entirely about bolted joint assembly and torquing procedures.
I grease all the threads on my bicycle ever since I had a bottom bracket seize into a frame and lost the frame. I have heard that you shouldn't grease lug nuts on a car, though. I'm not sure why, so take it with a a large pinch of salt. It might be simply because most people don't regularly check the torque on the nuts and in that case it's more desirable to have them seize than fail.
Many bolts have a lubed spec and a dry spec. The dry one is, of course, completely unreliable. If it is lubed and ain't turning smoothly, take it out and clean the threads. Or get a better grade of bolts.
Anecdotally, I've been using loctite C5A (copper anti-seize) on lug nuts for years without an issue. I also torque them to the manufacturer spec with a torque wrench twice a year (when I switch summer/winter tires).
I use hi temp wheel bearing grease for the lug nut lube, as it won't melt and run when hot. Don't want grease dripping on the brakes! The amount is also a tiny dab, half a drop is plenty. I don't use a torque wrench, just give em a hard twist, lower the tire to contact the ground, then twist them all again just to be sure.
If you live up north, every autumn take off every lug nut on every car wheel, and one at a time oil it and put it back on. You'll thank yourself when you're caught with a flat in freezing cold and howling winter winds.
In the UK (and elsewhere?) Lorry tyres have plastic caps on the bolts, with arrows aligned to each other in pairs, or some regular pattern. It's easy to see at a glance if a bolt has loosened.
I was one of the folks who put together the steel for a waterslide in a certain amusement park in California. Our method consisting of putting a mark across the bolt and nut after tightening it all the way down with a spud wrench, and then using a breaker bar until the mark on the nut was at the 4 o'clock position( or maybe it was 8, I don't recall ).
The inspectors would then use a telescope to check every mark. Completely blew my mind that they relied on this method, rather than something that measured the force directly.
Totally, but the crazy part is that there is nothing preventing you from making these marks without following the appropriate tightening procedure. When the project is several months late and people are working 16 hour days, the temptation to cut corners is high.
> making these marks without following the appropriate tightening procedure
If you didn't torque the bolt tight enough then it will come loose sooner, and the lines won't line up. I'm sure there are situations where the torque of the bolt is critical for handling peak load on the system, but for a lot of situations where a torque wrench keeps you from damaging by over-tightening, and makes sure you got it tight enough that it stays tight.
I should say there's one other failure mode a torque wrench can test that that the paint doesn't by itself, and that's a failing bolt. If you've ever seen a broken bolt, and the entire surface isn't uniformly shiny, then you've seen a bolt that cracked a long time ago and then failed recently. That crack is going to show up as less torque. So if the bolt hasn't spun but the torque has dropped, you might have a problem, rather than having a freak incident where the nut spun exactly 360° since you checked it last.
I could see an argument for using paint and smartbolts for fasteners with epic failure modes, like people dying or generators exploding.
Is it standard for there to be a follow-up bolt inspection some time after the initial assembly? This was a one-time gig for us, as we were welders by trade and boss-man got the contract from a family friend, so I'm not familiar with inspection standards.
For what it's worth, we tightened all the bolts down according to the procedure, despite pressure from boss-man to do otherwise for a few of them.
I haven't wrenched professionally for anything bigger than a bicycle, and in that case one of the most expensive components (labor and parts) can be damaged immediately by too much torque or over time by not enough, so you did not want to do that without a torque wrench. Or at least not until you had muscle memory for what 'enough' felt like.
On bikes, car repair and a few other items, mine and others, I've seen sheared off bolts. In at least two of those I was involved with the tightening prior to failure, and the lightbulb moment where we figured out why the sequence of events made sense.
"Nice video. Couple of points:
1: As per the title of your video, its worth emphasizing that these are tension indicating bolts, not torque indicating bolts.
2: With any bolted connection its the tension that is important. Whilst torque and tension should be correlated, that relationship varies considerably from bolt to bolt, lubricant to lubricant, hot to cold, state of corrosion etc...
3: So a bolt torqued to say 100NM may well have a tension variance of over 100%. The result is that bolts are often over or under tensioned, which can compromise the entire bolted connection.
4: Bolts like this (I've personally used Rotabolts, which are similar in concept but in my opinion better as they rely on a mechanical indication rather than a subjective color hue.) are very useful for certain applications, for example, sub-sea connections where divers have limited time and feeling, and sea conditions affect the bolt lubrication.
5: Other uses are for ensuring correct bolted connections on sensitive flanges, again offshore and sub-sea sees a lot of this.
6: Bolts like this are, in summary, brilliant for when you need a good quality bolted connection with correctly tensioned bolts. For most applications however they are unnecessary.
Keep up the good work!
:-)" - drawingboard82
Side note: youtube mobile when I tried to copy the comment wants me to sign in, to just copy a comment! wtf youtube! I just opened it in newspipe instead and copied from there
One thing missing here, but talked about (albeit not very clearly) in the video is that it’s not even a tension indicator, but rather, extension indicator. As long as we are in elastic regime, tension and extension are the same thing (Hooke’s law). However, once you go beyond it, tension goes down even as extension goes up. This is what the canuck meant when he talks about people tightening the loose bolt by giving it extra tweak, around minute 3:40 in the video. Once you leave the elastic regime, the bolt holding strength is permanently reduced, and by periodic tightening, sooner or later you’ll see it yield altogether.
It's annoying that, as you scroll down the page, the bolt animates to show it turning, but it scrolls out of view before it gets to the point where the main feature of the product would be shown.
Conop: an electric heater temporarily modifies the crystal structure and axially overloads the bolt, breaking it. We used these on a satellite that I worked on with deployable panels.
I've always liked ultrasonic bolt length measurement as the ultra high reliability way of measuring preload.
It can also be used for confirming the correct preload is still present, with the downside of having to track the original length of every fastener (which isn't really a big deal in high reliability applications)
I consult with a seismic expert at UC Berkeley about once yearly and he's pretty cavalier about pre-loading ...
Which is to say, he wants me to "pre-load the shit out of it".
Which is to say, our "indicator" is that we start to bend the HDB with the threaded rod. For instance, if we have two of these, horizontally, on either end of threaded rod:
SmartBolts won’t help if nobody looks at them. Unfortunately most rollercoaster accidents are caused by humans simply failing inspect structures, ignoring the results of inspections or disabling safety systems. Rather than inspections being too difficult to perform.
I can guarantee a roller coaster track at any modern amusement park in America is inspected far more frequently and is much safer to travel on than the interstate highways and bridges that get you to the parking lot.
I worked at an amusement park during summers in highschool and coaster track maintenance was serious business. The entire tracks were walked and inspected end to end twice a day (at open and at close). There was a meticulous paper trail of any and all maintenance, measurements, conditions, etc. Their insurers demanded a high standard because ultimately it would have cost the park millions and millions of dollars in liabilities if there were accidents.
Thanks! Forgive me but I gotta ask- how would you describe the socioeconomic class of the folks the park served? Can they afford to sue over small, non life-threatening accidents caused by minor safety breaches? Was the park ever sued, and how did it go? (My line of inquiry is coming from having seen abhorrent safety standards upheld at a major mainstream park, that was the poor people park in the region - the same company had another nearby park for the suburbanites, that was much nicer)
In my experience, the most common safety practice on chairlift (poles) is a double-nut. It's very common to see all through North America - no washer, just two nuts stacked.
I've never inspected them to see if they have indicators painted on, etc. - one would assume they should ...
I've also noticed that the nuts go on top. I've always wondered if this was so it was completely obvious if a bolt dropped out (i.e. sunlight coming through the hole).
I am surprised there aren't already some chip for it, or is there ?
Something based on RF-energy harvesting, you beam it with radio waves, it uses the energy to take a pressure measurement and send you back the result, along with the id of the bolt. And you inspect all your factory bolts in a matter of seconds, and everything is nicely logged, even those hard to inspect bolts.
To measure the pressure either some piezo-resistance, or some capacive-sensing between two washer separated by a squeezie dielectric (Could a FR4 pcb-washer hold the pressure ?), or an integrated MEMS-pressure sensor.
If your technician needs to tighten the bolt, he has to get close so he can transmit more RF energy so you can even have a led, that could turn on when the pressure is right.
In some real deal applications like connecting rods on engines you can stick your head into. Techs will measure when a bolt has reached a correct torque spec when the bolt has stretched to certain dimension measured with a micrometer.
Torque is also very misleading depending on material. Steel bolts stretch in what feels very linear. Stainless steel bolts, when those are tightened up it's like hitting a wall going from loose to tight.
Click sticks (torque wrenches) also have something to say. Where you hold your hand on the wrench will affect the torque value. Usually there is a line on the handle showing you exactly where your hand should be placed and pulling from.
I guess I don't see the practical application. These will fill with grime in days if not seconds, depending on application. A torque wrench and loctite more or less make something like this unnecessary.
If it's for some specific scientific applications, more power to them. But let's not pretend they just saw something so obvious everyone else has been missing.
Edit to add: I actually feel like these should be reverse designed. A small tit that sticks up would probably be much more evident than a hole in most applications.
If you think the head of a bolt with an indentation in it is going to stay clean, especially one that has to stay tight, then you have not held a wrench often enough, my friend.
Once that red spot gets dirty, you're not going to be able to tell if it's brick red because it's loose, or brick red because it has dirt on it. It's probably going to take you longer to clean the bolt than to get the torque wrench on it.
Not all tension controlled scenarios are dirty though. Working with a lot of stainless recently in controlled environments, galling is a big friction variable so instrumented bolts can be crticial.
Look at the pictures on the website and I think you'll follow me.
I was thinking of brown specifically but black has the same effect. When it's partially covered the color will be the average of the two. Probably black if it's near pavement, brown if exposed to nature.
Could be interesting to apply this to crew boats which A) people are used to paying a lot for the equipment and B) people often have to assemble and disassemble with bolts, and loose bolts are certainly a point of failure during a race.
Wait I didn’t read anything about requiring a subscription to a cloud service before I can tighten the bolt. Nor how my phone will be involved in the process. And no blockchain?
This isn’t “Smart” as I have understood we define it now.
Seems like something that would be very useful for furniture or mechanisms that are self assembled like Ikea, chairs etc by regular people. Easy visual inspection when things are loose.
This is a bad name. The word "smart" implies the bolt can connect to my phone via bluetooth and I can download an app that will tell me the status of the bolt.
It does imply that... Nowadays, unfortunately. This is bad, because "connect to my phone via bluetooth and I can download an app" is often not a very smart way at all to do something.
Yet another example of how marketing abuse of language fucks up everything.
I was just thinking that these don't have wifi, an ip address, contact the mothership via aws to make sure the maintenance contract is paid up and TOS clicked...such a missed opportunity...
Due to the washer style can be used with a wide range of fasteners. The most common type, in my experience, due to the ease of use, has a little bit of colored goo inside the arched cells. The goo squirts out when the specified torque is reached.
That being said, there are a lot of approaches to this same problem. Another common technique is breakaway bolts that are driven with a piece that snaps away when a certain torque is reached: https://youtu.be/lrCoi3gaLfU