Smart bolts

[spyug]

A copy of information posted by Laotzuistruth on the XS650 Garage forum:http://www.smartbolts.com/index.htm

Very interesting development in bolt rechnology. I can see real use in bikes like the XS where everything shakes loose in quick order. GSs not so much but for peace of mind....great idea.

Cheers all,
Spyug

[Agemax]

seems like a very expensive gimmick to me. a torque wrench to tighten them up and either a spring washer or some locktite to stop them coming loose is a far better and cheaper option

[Dogma]

On bikes it probably would be a gimmick. I've seen these things in engineering magazines for a while now. They're for those critical applications where you need to know the tension on the bolt. There's a degree of uncertainty with a torque wrench, even a quality one tightening a lubed screw. Also handy for service inspections, since they will tell you if the bolt is loosening or stretching.

[Agemax]

On bikes it probably would be a gimmick. I've seen these things in engineering magazines for a while now. They're for those critical applications where you need to know the tension on the bolt. There's a degree of uncertainty with a torque wrench, even a quality one tightening a lubed screw. Also handy for service inspections, since they will tell you if the bolt is loosening or stretching.

if fitted in a critical application i am sure they would make adequate precautions to make sure the bolt doesn't come loose in the first place

[bwringer]

Man, these things are expensive! Leftover sample bolts are about $25 each.

I kind of wonder how well they withstand heat, and the fluid capsules seem vulnerable. I suspect they're intended more for protected areas of construction than machinery.

The "poor man's" way to ensure that bolts stay put is this brittle goop that cracks and changes color if the fastener moves at all.

Looking for a link...

[Dogma]

if fitted in a critical application i am sure they would make adequate precautions to make sure the bolt doesn't come loose in the first place

That's why I mentioned bolt stretching as one condition these would detect. A bolt that is stretching under load won't be helped by any locking devices (which are probably also present).

[Guest]

All bolts stretch under load. A torque wrench, used with clean threads and anti-seize compound, measures the tension developed as the bolt stretches.

[Dogma]

All bolts stretch under load. A torque wrench, used with clean threads and anti-seize compound, measures the tension developed as the bolt stretches.

Yes, that's how these work. The screws have a hole through the center with a precise amount of fluid in it. As the screw stretches, the volume of that hole increases, drawing more fluid into the body of the screw, and out of the head. The amount of fluid visible in the head decreases until a dot of the correct size is all that's left visible.

I was referring to stretching due to fatigue, creep or increased loading for some reason other than torque applied to the head. So, if the tension and strain induced on the bolt after proper torquing is no longer on the screw when you come back to check it, this screw can tell you. Re-torquing to check tension is not always an option, or may not be precise enough.

I seem to recall that they were also working on an electronic version of this that would work with something similar to an RFID reader. That way you can check large groups of fasteners just by waving the reader over them, or even have continuous monitoring.

[Agemax]

doesn't that defeat the object? having a bolt in a critical area which has a hole drilled through its length, this would decrease the bolts strength and longevity straight away, causing it to stretch prematurely

[Dogma]

doesn't that defeat the object? having a bolt in a critical area which has a hole drilled through its length, this would decrease the bolts strength and longevity straight away, causing it to stretch prematurely

I'm sure it does decrease the strength somewhat, maybe a few percent. As I recall the hole is tiny, like 0.5 mm, probably ram EDM'd. But some critical joints are all about maximum grip, while other critical joints need to be easily inspected, and can give up a little strength.

I'm trying to think of an application example, and all I can think of is someplace like the hot areas of a nuclear reactor. Someplace where visual inspection by camera is possible, but putting a wrench on it is not. That's also a place where the steel may not stay steel indefinitely. (There's a family of stainless steels that are fairly immune to transmutation, but I'm not sure which.)

[howling60]

The "poor man's" way to ensure that bolts stay put is this brittle goop that cracks and changes color if the fastener moves at all.

Looking for a link...

"torque-seal" or something of the sort... also called inspection paint.

www.mcmaster.com bright orange = 1476T114 lots of variety to choose from!

-nate

[Shaughn]

I'm trying to think of an application example, ....transmutation...

They list applications on the website:

http://www.smartbolts.com/clients.htm

Embrittlement would be the more immediate concern. The design trend on the new (gen III+) reactors is simplicity and reliability, i.e. passive controls such as gravity driven grey and black rod insertions, and less reliance on novel technologies.

[suzukiSam]

if liquid core, what about bolts that are inverted or on an angle ? gravity must play havoc with the color of that little dot..

[bwringer]

if liquid core, what about bolts that are inverted or on an angle ? gravity must play havoc with the color of that little dot..

As long as there are no air bubbles, position will make no difference.

[bwringer]

"torque-seal" or something of the sort... also called inspection paint.

www.mcmaster.com bright orange = 1476T114 lots of variety to choose from!

-nate

Yeah, that's what I was thinking of. It doesn't really prevent movement, but it simply makes any developing problems very easy to spot.

Fortunately, vibration loosening is not a big issue in the GS world.