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News Release from: Stage 8 | Subject: GrooveLok fastener locking system
Edited by the Engineeringtalk Editorial
Team on 14 December 2005
Fastener locking system helps avoid
joint failures
For fail-safe joint integrity in critical applications, an innovative fastener locking system can stop joint failure and production downtime by preventing thread loosening from starting.
For fail-safe joint integrity in critical applications, USA companies are adopting an innovative fastener locking system that can stop joint failure and production downtime by preventing thread loosening from starting, even in counterbored hole applications "Like David slew Goliath, a single weakness can take down even the biggest, most capable, production machinery," says Joe Finan, vice president of the Advanced Technology Group for Sequa Can Machinery, a leading maker of can manufacturing equipment, based in East Rutherford, New Jersey, USA
This article was originally published on Engineeringtalk on 14 Nov 2005 at 8.00am (UK)
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Innovative fasteners avoid dangerous failures
Stage 8's patented GrooveLok technology locks the threaded fastener in place so there is no way it can come loose under the influence of externally applied loads.
Locking system keeps critical joints intact
US industry is adopting an innovative fastener locking system that can stop joint failure and production downtime by preventing thread loosening from starting, even in counterbored hole applications.
"The fatal flaw in too many production lines is failing to protect the critical joints with suitable fasteners.
"Companies will spend a ton of money bulletproofing major components, yet neglect the fasteners.
"It's insane when you think about it because the fasteners hold the components together.
"Shock, pressure, vibration, temperature change - all combine to loosen fastener threads, which inevitably come loose at the worst possible time, when you can least afford it.
"From the start, you've got to get the critical fasteners right so you're not dealing with the consequences of inadequate joint integrity.
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"You don't want to bring a multi-million-dollar machine to its knees for want of an adequate fastener".
Though Finan's advice holds true for most industrial machinery today, it is particularly applicable to high-speed machines with complex drivetrains, where a single loose bolt backing out can trigger a cascade of failures.
Since a catastrophe of this sort could halt production for days, Sequa, along with a host of other USA manufacturers, is leaving nothing to chance.
For critical joints - even in counterbored applications - these companies are turning to an innovative mechanical fastener locking system that is designed to prevent threads loosening from the beginning.
This virtually eliminates critical joint failure due to bolt loosening and greatly reduces emergency repairs, costly production downtime, loss of customer trust, and potential liability.
While traditional fastening methods such as prevailing torque, deformed threads, and chemical bonds may be fine for non-critical applications, they are inadequate for production machinery where joint integrity is crucial.
Once a fastener begins to loosen under vibration, jarring, temperature change, or even use of machinery beyond engineered tolerances, joint failure is imminent.
In these situations, relying on maintenance schedules to check and retighten bolts is folly - not only because of the risk of production stoppage and cost of labour, but also due to the difficulty of obtaining equipment access, the risk of over/under-torquing fasteners, and the sheer number of parts to be inspected.
"If you can loosen a fastener at a critical joint, do not use it," says Finan.
"Because if you can loosen the fastener, the physics of your application will.
"It is Murphy's Law.
"Typical fasteners just are not robust and do not handle unanticipated events well.
"And, of course, unanticipated events happen with more frequency than we think.
"Machinery is run faster and longer than it is designed for, it is overloaded, and maintenance is skipped.
"Critical joints in production machinery have to be fail-safe in an environment that is never going to be ideal".
To safeguard the structural integrity of drivetrains and other critical components for Sequa Can Machinery, used in making canning equipment for industries ranging from food and beverage to aerosol and specialty, Finan turned to Stage 8 locking fasteners.
He did this to avoid wasting time, money, or customer trust trying to fix production problems better solved in design.
Stage 8 manufactures what is claimed to be the only active mechanical fastener locking system designed to stop joint failure/production downtime by preventing thread loosening from starting.
Essentially, its patented GrooveLok fastener locking system acts like a small wrench locked onto a bolt head, with the wrench handle braced against a stationary object, such as a frame, casting or protrusion.
This stops any counter rotation of the bolt, and hence bolt loosening, until the locking system is removed.
The system works the same way with nuts.
It includes a grooved nut or bolt, an application-specific retainer (which serves as the 'wrench socket and handle'), and a spring clip, all of which work together.
If there is nothing to brace against to stop loosening, a special bridge retainer can fit over two or three bolts, locking them together, or a retainer can be bent over an edge or frame.
Perhaps the locking system's most appreciated application is with counterbored holes, which normally require tedious torque checking and screw re-tightening with typical fastening methods.
However, once Stage 8's locking system is in place - requiring just a small milled slot adjacent to the counterbore for the retainer to slip into - fasteners never need to be re-tightened.
Thereafter, they can simply be scanned by eye to check for joint integrity, without labour-intensive torque gauges or bolt re-tightening.
"If you see the clip and retainer locked in place, you know the fasteners retain their full pre-load," says Finan.
"That speeds inspection and gives peace of mind.
"Until you remove the clip and retainer, the nut or bolt will not move because they are physically restrained.
"They literally cannot be defeated, unlike traditional fastening methods.
"You will not lose pre-load on any critical joint due to bolt loosening because it is physically impossible for the fasteners to turn.
"Loosening never has a chance to get started".
Since the GrooveLok fastening system by Stage 8 does not rely on fastener threads, clamp load, or anything other than physical restraint to keep nuts and bolts locked in place, no internal or external forces will loosen it until removed.
The system retrofits existing components, is fully reusable, and has been used in items as small as eyeglass screws, to bolts as large as 8in holding generator propellers onto a hydroelectric dam.
To date, the system has no reported failures in over 10,000,000 applications.
"With Six Sigma and other quality measures prevalent today, our engineers need to focus on big issues like defect analysis or designed failure modes," says Finan.
"Not whether commercial bolts will come loose.
"Fortunately, the Stage 8 locking system ensures that critical joints stay intact.
"This frees our engineers to solve larger problems".
For its many canning applications in various industries, Sequa takes advantage of Stage 8's ability to provide application-specific locking fasteners in a wide range of sizes, materials, thread pitches, and retainer configurations.
For instance, Sequa used a counterbore locking fastener arrangement to secure a several-thousand-pound flywheel to canning machinery.
Stage 8 also designed a special seven-point heptagon retainer for Sequa that not only gave them the exact torque needed on connecting rods, but also provided locking on a nut that never has to be adjusted for maintenance.
Sequa highlights its use of Stage 8 locking fasteners in sales literature and technical presentations.
"Right up front, we show prospects and customers our attention to detail and quality," says Finan.
"From the smallest component upward, they need to know our machinery will serve them well".
If any company has put Stage 8 locking fasteners to the test, it has been Grand Island, New York-based Viatran Corporation, a leading manufacturer of pressure transducers/transmitters for the oil, auto, and wastewater industries.
In harsh oil field pumping applications where there is 10,000/15,000psi pressure, severe shock, and continuous vibration, several Viatran level and pressure sensors are protected by encapsulating 'shells' held together by Stage 8 locking fasteners.
"The fasteners used to encapsulate and protect the sensors must be back-out proof," says Mike Hallock, Viatran's purchasing manager.
"Every hour of downtime costs thousands of dollars in the oil industry".
Prior to using Stage 8 locking fasteners, Viatran tested typical fasteners such as split washers and chemical bonds, finding that these failed to adequately hold each sensor's encapsulating shell together.
Viatran settled on a lockwire system to encapsulate and protect its sensors in the field.
But this was cumbersome to install, and tended to damage the outside of each sensor on removal for repair.
Consequently, repairs had to be done by Viatran in its manufacturing facilities, adding to overall repair times.
Seizing the chance to improve its product and customer experience, Viatran turned to Stage 8 locking fasteners to securely encapsulate its sensors, while speeding repair and maintenance, when necessary.
As part of a 'down-and-dirty' shock test, the transducer was mounted on a fixture with a Weco nut - this was accomplished by fastening the nut on the outside diameter of transducer-and pounded with a 10lb sledgehammer to simulate the punishment it would receive in field installation.
When customers beta-testing the improved fastening method gave it a thumbs up, Viatran adopted it for its oil field applications.
"Reliability is what we base our reputation on," explains Hallock.
"For the reliability our customers need, we need absolute joint integrity.
"That is what Stage 8 provides.
"Not a single fastener has failed in the field for 15 years.
"That is how we like it".
Additionally, since the locking fasteners are easy to install and remove, certified technicians can now do so in the field.
This eliminates the need to return sensors to Viatran's manufacturing facilities for repair, and cuts turnaround repair time by up to a week or more, when necessary.
"If you have got a critical fastening application that is prone to vibration, shock, or other harsh environmental factors, try the Stage 8 locking system," concludes Hallock.
"It has improved our good reputation in the field.
"We have had favorable feedback and repeat orders for years and years".
For more info on Stage 8's patented GrooveLok technology and products, visit the company's website.
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