Rivets vs. Screws: How to Choose the Right Fastener for Aircraft Assembly

On aircraft, fasteners are vital for securing everything from major assemblies to the tiniest of electronics. With this in mind, a wide array of fastener types are employed to meet diverse service requirements, but rivets and screws are two of the most prominent across all areas of an aircraft. Selecting the appropriate fastener when assembling or working on an aircraft is a critical step in safeguarding structural integrity and allowing for appropriate maintenance in the future, so read on as we cover everything you need to know about making the right choice between rivets and screws in this blog.

The Use of Rivets in Aircraft

Rivets are non-threaded fasteners designed to create permanent connections by deforming the tail to form a second head, clamping components tightly together. Riveted joints resist loosening under vibration and transmit shear loads while minimizing stress concentrations, making them particularly well suited for structural applications like fuselage panels where repeated disassembly is not anticipated. Some common rivet types used on aircraft include:

• Solid Rivets: These traditional rivets have a solid shank that is deformed on the tail to form a permanent joint.
• Blind Rivets: Designed for one-sided installation, blind rivets create a strong joint in areas with limited access, employing a mandrel that is pulled through the body using a rivet gun to deform and expand the rivet tail.
• Cherry-Lock Rivets: Designed as semi-tubular rivets with a locking groove and partially hollow shank that expands, cherry-lock rivets are able to create a permanent joint while requiring less installation force than a standard type.
• Lock Bolt Rivets: Lock bolt rivets are two-piece fasteners consisting of a solid pin and collar, which mechanically lock together to form a high-strength joint. 
• Hi-Lok Rivets: Building off the design of lock bolt rivets, Hi-Lok rivets combine a threaded pin and a collar for torque-controlled installation, combining the permanent shear strength of a rivet with the clamp load capabilities of screws.

As far as their limitations go, rivets do not enable adjustable clamping or torque control like threaded fasteners do, limiting their flexibility in applications where a more exact preload is needed.

The Use of Screws in Aircraft

With a threaded shank that allows for removal without causing damage to the components being connected, screws are extensively used in areas like instrumentation or engines that require periodic maintenance or replacement. Being well-suited for tensile or clamping applications, screws allow torque-controlled installation that provides precise preload and promotes uniform joint integrity throughout their service life. These fasteners are available in a wide range of shank lengths and sizes, thread pitches, and head styles, but the most frequently-employed types in aviation settings include:

• Machine Screws: Machine screws are the variants chosen for general-purpose assembly, commonly paired with additional components like locknuts or nutplates to prevent loosening under vibration.
• Self-Tapping Screws: With a sharp, hardened tip and cutting threads designed to form mating threads in sheet metal or other softer materials during installation, self-tapping screws are primarily utilized in non-structural applications where ease of removal is important.
• Structural Screws: Structural screws contain a partially unthreaded shank that allows the smooth portion to bear shear loads more effectively, while the threaded section provides secure clamping, serving load-bearing joints well.

When utilizing any screws, it is important to keep in mind that they can introduce stress concentrations along their threaded regions, decreasing their effectiveness in pure shear applications. They also have a greater tendency to loosen under vibration if not properly secured with locking mechanisms, which inherently adds to both the complexity of assembly and its overall weight.

Pointers for Choosing Between Rivets and Screws

The decision between fasteners is rarely binary, with designers and maintenance engineers weighing multiple factors. In most cases, you can walk yourself through the following steps to make the best choice:

Step 1: Identify the Load Type

• If the joint is tension-dominant or requires a controlled clamping force, screws are likely more suited for the job.
• If the joint is shear-dominant, rivets generally perform better.

Step 2: Consider Fatigue and Stress Concentration

• As we previously mentioned, screws can act as stress risers and may exhibit earlier fatigue initiation.
• Rivets do not present threading stress concentrations, and furthermore, some rivets can outperform threaded fasteners under continuous vibration. 

Step 3: Determine Access and Removal Needs

• If you expect the joint to be disassembled or components to be accessed on even a semi-regular basis, screws are more favorable.
  
• If no removal is expected outside of major repairs, rivets are a good option.

Secure the Aircraft Fasteners You Need from a Trusted Source

In all, the choice between rivets and screws in aircraft assembly relies on aligning their properties with joint performance requirements. Successful outcomes depend on evaluating load paths, maintenance accessibility, and fatigue resistance, coupled with the careful procurement of high-quality fasteners. If you are in the market for aircraft rivets or screws, we invite you to explore our selection on ASAP Aerospace.

Through this ASAP Semiconductor platform, you can readily purchase countless aircraft fasteners and other such parts sourced exclusively from industry-leading and trusted manufacturers. Moreover, we aim to simplify procurement with convenient quotation services and solutions that are tailored to the distinct needs of each customer. Knowing what we bring to the table, peruse our inventory and get in touch with our team to start purchasing the products you desire.