igh-impact aircraft riveting joins aluminum sheets, typically requiring two people who get exposed to repetitive, hammering forces. One person normally uses a riveting gun while a partner on the other side of the joined material holds a bucking bar – effectively a hand-held anvil that forms the end of the rivet, or bucktail.
Repetitive impact and vibration conveyed to bucking bars can lead to health or ergonomic complaints. On average, 46% of workers who use vibrating power tools contract Hand Arm Vibration Syndrome (HAVS), a painful, potentially disabling condition of the fingers, hands, and arms.
“People don't understand that the person on the receiving end [of rivet bucking] is taking highly damaging vibration to the hand,” says Richard Borcicky, a retired tool engineer and ergonomics manager who oversaw safety at the Department of Defense’s (DOD) Fleet Readiness Center East base in Cherry Point, North Carolina.
Borcicky says the DOD continually seeks to improve safety and ergonomics in its facilities. Through implementing industry best practices, Borcicky notes the Fleet Readiness Center East base was able to reduce annual carpal tunnel syndrome cases from 50 to 0.
However, Borcicky says people bucking rivets often experienced hand swelling during the week, and throughout time, this can develop into an incurable, crippling disease of the fingers and hands.
“We couldn’t get rid of the bucking bar issues because there was no fix,” Borcicky says.
Brian Lewis, lead engineer at the Tulsa, Oklahoma facility of Spirit AeroSystems, the world’s largest tier-one manufacturer and supplier of aerostructures, adds, “Without an ergonomically friendly bucking bar that absorbs impact and vibration, you have to continually switch out workers because they cannot rivet all day long, but that in itself can cause some quality issues.”
However, rivets still must be reliably and evenly driven without marring airplane skins, or they must be drilled out, deburred, and redone – and such rework increases production costs. This can be a particular challenge for under-trained staff or new hires, who are often assigned riveting tasks.
“Due to the force and impact of riveting, rivets and bucktails can be misaligned – but these need to be just right each time,” Lewis says. “So, having the right ergonomic equipment to facilitate fast, reliable production is critical.”
While some bucking bars incorporate tungsten to absorb and dissipate vibration, it’s seldom sufficient to fully address impact/vibration related repetitive injury or ergonomic issues. If dropped, tungsten bucking bars can break, making them unusable.
Fortunately, to speed reliable aerospace riveting while minimizing injuries, the industry has developed safe, ergonomic, impact absorbing bucking bars that can be tailored for ease of use in aerospace riveting processes.
Faster, safer riveting
According to Lewis, Spirit AeroSystems’ Tulsa facility primarily builds new parts for wing structures, such as slats and flaps, which require large quantities of rivets.
“With the traditional bucking bars, riveters can develop elbow or shoulder issues, so it isn’t prudent to leave people in that role for very long,” Lewis says. “Also, the rivet bucktails sometimes are not the same height; and the bucking bars can leave marks on sheet metal surfaces, which is not acceptable.”
In search of a solution, Lewis was receptive to the recommendation of an airline maintenance employee at a nearby facility, who had successfully used an advanced bucking bar called the Torpedo Guardian ISOVIB from Honsa, a Milan, Illinois-based manufacturer of ergonomic bucking bars and power tools to improve productivity and reduce injuries.
The advanced bucking bar, developed in collaboration with Richard Borcicky’s expertise in safety and ergonomics, provides three levels of vibration reduction: a wave spring, tungsten inserts, and a cushioned palm pad. Compared to traditional bucking bars, this reduces vibration up to 50%.
Lewis says the bucking bar manufacturer came to the Tulsa facility, demonstrated the bucking bars, and let the mechanics test them.
“One of our mechanics had shoulder surgery after an unrelated injury, and was unable to rivet using typical bucking bars,” Lewis explains. “When we let her try the Honsa bucking bar, she was able to rivet without the impact and vibration hurting her shoulder. She spoke to our leadership team to get the first order pushed through, and later several more orders were placed for different areas in the plant.”
The advanced bucking bars include a precision non-mar height gage that can eliminate over-bucking and damage to metal and/or painted surfaces, ensuring that less-experienced riveters produce the same height bucktail on every rivet.
Experienced riveters get a feel for properly set rivets,” Lewis says. More advanced bucking bars allow less experienced personnel to install rivets faster, with better feel.
Aerospace producers need bucking bars in potentially thousands of different shapes and sizes to suit specific applications, so customizing the modular bar with interchangeable end effectors can allow operators to reach a wide variety of difficult rivets.
“Honsa was able to custom make a solution for pretty much every area we had – it was not one product for the whole plant,” Lewis says. He notes that the manufacturer was able to turn rough drawings from workers on the plant floor into fully engineered drawings. “We went back and forth with their design team to get a truly custom solution and they were very easy to work with.”
Using advanced bucking bars significantly improved production and safety in Spirit AeroSystems’ Tulsa facility, Lewis says.
“The ergonomic bucking bars have definitely helped our production flow and reduced riveting redos by about 10% to 20%,” Lewis adds. “Anytime we can move the needle in terms of quality, it is a good thing for us and the customer.”
Using impact- and vibration-reducing tools has boosted crew morale as well. As a result, he has already recommended their use to other Spirit AeroSystems facilities in the U.S. and overseas.
“Our work crew tends to do the same riveting tasks over and over,” Lewis concludes. “So, anytime we can help them do their job better and prolong their career, it is a win-win. For anyone doing aerospace riveting, switching over to advanced bucking bars is really a no brainer.”