High-speed machines with complex drive trains require protection of critical joints with suitable fasteners. Companies will continuously spend to protect major components, yet neglect the fasteners.
Sequa Can Machinery
Joe Finan, vice president of Advanced Technology Group for Sequa Can Machinery, advises leaving nothing to change when it comes to protecting Sequa’s production line.
“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,” Finan said. “From the start, you’ve got to get the critical fasteners right so you’re not dealing with the consequences of inadequate joint integrity. You don’t want to bring a multi-million dollar machine to its knees for want of an adequate fastener.”
For critical joints, even counterbored applications, these companies are turning to a unique mechanical fastener locking system designed to prevent thread loosening from the beginning. This virtually eliminates critical joint failure due to bolt loosening which will greatly reduce emergency repair, costly production downtime, loss of customer trust and potential liability.
Traditional Fastening Methods Fall Short
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 use of machinery beyond engineered tolerances, joint failure is probable. In these situations, relying on maintenance schedules to check and retighten bolts can be risky. This is due to the jeopardy of production stoppage and cost of labor, as well as the difficulty of obtaining equipment access, the risk of over/under-torquing fasteners and the sheer number of parts to be inspected.
“Typical fasteners just aren’t robust and don’t handle unanticipated events well,” Finan said. “And, of course, unanticipated events happen with more frequency than we think. Machinery is run faster and longer than it’s designed for, it’s overloaded, maintenance is skipped, etc. Critical joints in production machinery have to be fail-safe in an environment that’s never going to be ideal.”
A Fail-Safe Fastening System for Critical Joints
To safeguard the structural integrity of drivetrains and other critical components, Finan turned to STAGE 8 Locking Fasteners, Inc.
STAGE 8 manufactures an active mechanical fastener locking system designed to stop joint failure/production downtime by preventing thread loosening. 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. This stops any counter rotation of the bolt until the locking system is removed.
Once STAGE 8’s locking system is in place, requiring a small milled slot adjacent to the counterbore for the retainer to slip into, fasteners never need to be re-tightened. They can be scanned by eye to check for joint integrity, without labor 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’re physically restrained. You won’t lose pre-load on any critical joint due to bolt loosening because it’s physically impossible for the fasteners to turn. Loosening never has a chance to get started.”
Since the GrooveLok fastening system doesn’t 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 eight-inch holding generator propellers onto a hydroelectric dam. To date, the system has no reported failures in over ten million 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 example, Sequa used a counter bore locking fastener arrangement to secure a several thousand pound flywheel to canning machinery. STAGE 8 also designed a special 7-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.
A Secure System for Harsh Applications
One company that has put STAGE 8 Locking Fasteners to the test is Viatran Corp., a leading manufacturer of pressure transducers/transmitters for the oil, auto, and wastewater industries. In harsh oil field pumping applications where pressure levels reach 10,000/15,000-PSI, and severe shock and continuous vibration conditions exisit, 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 down time 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, but found that these failed to adequately hold each sensor’s encapsulating shell together. Viatran decided on a lockwire system to encapsulate and protect its sensors in the field. This was cumbersome to install however, 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.
Utilizing the opportunity 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.
“Reliability is what we base our reputation on,” explains Hallock. “For the reliability our customers need, we need absolute joint integrity. That's what STAGE 8 provides. Not a single fastener has failed in the field for 15 years. That’s how we like it.”
The locking fasteners are easy to install and remove so certified technicians can now complete these tasks in the field. This eliminates the need to return sensors to Viatran’s manufacturing facilities for repair, cutting turnaround repair time by up to a week or more.