A Boeing 787 has approximately 2.4 million fasteners, accounting for half of the total components of the aircraft. 78% of these fasteners are rivets, and each one is driven into the joint using an air hammer rivet gun. It is not to be confused with the air hammer, which, although similar in appearance, mechanism, and even in name to the rivet hammer, serves a very different purpose.
The viability of the aerospace industry as a business depends on many things, one of which is how efficiently an aircraft is assembled. Further, in aircraft assembly, productivity is determined by how fast the components are joined using fasteners.
In this article, we will discuss the importance of the rivet hammer in the aerospace industry and how it works differently from the air hammer.
Most people could not tell the air hammer apart from the rivet hammer with a cursory glance. They also work in a similar manner. However, there is a slight -- but important -- difference in their mechanisms.
The air hammer, also known as a power hammer or pneumatic hammer, is generally used to carve or chip away at a stone, metal, or other similarly hard material. It is also used to dig holes or cut through a hard surface. In essence, it is a much more efficient chisel or hammer. It can deliver a lot of power but lacks precision, and this deficiency greatly limits its application in the aerospace industry.
Similar to the rivet hammer, the air hammer is powered by compressed air supplied from a compressor through a hose or tube. It has three parts that facilitate the drilling or hammering: the cyclic valve, the cylinder or barrel, and the piston, which moves back and forth, pushing the tip or head to make the hole. The tip can be replaced, depending on the application. A hammer tip, for instance, is used to give shape to hard materials while the chisel tip is used to score or cut into a surface.
When the air hammer is triggered, the valve allows the compressed air to enter the cylinder and push the piston inside it forward. With its velocity, the piston also pushes the tip attachment, which is at the other end of the cylinder. From this position, the piston triggers the valve and releases the compressed air, after which a spring pushes the piston back to its original position, completing one cycle. This happens very rapidly -- at a rate of thousands of cycles per minute.
The power in each cycle, although very high, is not precise as the mechanism of the hammer allows for "off" and "on" mode only, and no means to regulate the compressed air.
Driving a rivet requires more finesse, something that the air hammer could not deliver. The rivet has to be "squeezed" at its ends with just enough power to buck the other end and secure the joint. In aircraft assembly where there are many types of rivets, the tool that drives them has to adapt accordingly -- and this is the main difference of the rivet hammer from the air hammer.
The process by which the rivet hammer drives a rivet is similar to how the air hammer works. Once the rivet gun is triggered, compressed air enters through a throttle valve and pushes the piston forward, which in turn makes contact with the rivet. The air is then released, and a spring pushes the piston back again. The one difference is the presence of a regulator than can be used to adjust the power delivered by the tool, depending on the application.
As the rivet head is being pushed by the piston of the rivet gun, the bucking bar pushes back at its tail end and deforms it at the same time to secure the lap joint. This is the basic function of the bucking bar, but it also serves to absorb some of the force from the rivet gun to reduce the vibration.
An efficient riveting system is essential in aircraft assembly, and it is not complete without some of the following tools.
RRH04 Riveting Hammer - The RRH series of riveting hammers have a revolutionary ergonomic design and a unique vibration-dampening system. This model, paired with the RBB04 bucking bar, makes for an unbeatable riveting system.
RRH06 Riveting Hammer - Aside from its superior ergonomic design and vibration-dampening system, the RRH series of riveting hammer offers adjustable power options using a feather trigger or regulator to meet your various riveting needs.
RRH08 Riveting Hammer - This tool has an easy and comfortable grip for first-in-class ergonomics. It also has a highly robust and durable design. With this model, both operator and tool could withstand hours of riveting without risk of injury or damage.
RRH10 Riveting Hammer - The RRH series tool can easily accommodate rivets of up to 13mm in diameter. It has a pistol grip with a rubber coating that is vibration-damped for optimum performance.
RRH12 Riveting Hammer - This is a high-powered tool that makes tough riveting tasks comfortable and easy for operators. The vibration-dampening system reduces the risk of "white fingers" and other musculoskeletal disorders from hours of riveting.
RRH14 Riveting Hammer - The RRH series rivet hammer is a high-performance tool designed with operator safety and productivity in mind. With this in your tool cart, riveting costs will go down, and your profit margin will go up.
RN11 Riveting Hammer - For applications where accessibility is critical, the RN series tool is the best option. This model is the smallest riveting hammer in the market, but it does not lack in power. Its trigger is easy to operate, giving excellent control to the user.
RRN18 Riveting Hammer - This tool is also an excellent option for riveting applications in cramped spaces. It has a compact design and comes with a short shank rivet set for high accessibility.
RBB04 Bucking Bar - This bucking bar reduces the reaction forces from impact using a vibration-dampening spring element, eliminating the need for supply air to operate. It is the perfect companion to the RRH04 riveting hammer.
RBB10 Bucking Bar - This bucking bar also uses a spring element to dampen vibrations. It can be fitted with different dolly configurations with its quick-change retainer and can be used in any possible workspace.
Manual riveting accounts for 50% of the total labor cost in aircraft manufacturing. It remains to be the most tedious and repetitious stage in the extensive aerospace product supply chain. Atlas Copco offers a wide range of riveting tools that can maximize operator productivity, reduce vibration related injuries and minimize the cost of the riveting process.
Contact us now for a free quote of our high-performing aerospace tools.
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2. Doityourself Staff, How Does a Pneumatic Hammer Work?, Doityourself, April 06, 2010
3. Beckwith, Wayne, Pneumatic Hammer Internals, https://www.youtube.com/watch?v=dOxRHBePY98, July 10, 2012
4. Staff, Operation of a Rivet Gun, Bright Hub Engineering, June 11, 2011
5. Xi, Feng-Feng, et. al., Framework on robotic percussive riveting for aircraft assembly automation, Springer Link, April 06, 2013