In determining the standards for the categories of fasteners that perform well on various categories of aircrafts and spacecrafts, one of the key characteristics required is a much lighter weight than in any other industry. It is easy to understand why you cannot rely on fastening solutions with the same weight when trying to achieve […]

In determining the standards for the categories of fasteners that perform well on various categories of aircrafts and spacecrafts, one of the key characteristics required is a much lighter weight than in any other industry. It is easy to understand why you cannot rely on fastening solutions with the same weight when trying to achieve air or space travel. Constructors are trying to reduce the amount of energy and consequentially the quantity of fuel required to lift the craft off the ground and into the skies, maintaining it airborne for as long as it is necessary.

Are aerospace fasteners lighter and therefore less reliable?
The reliability of the fasteners cannot be neglected in favor of the lighter weight. All components of the air/spacecraft – from the wing assemblies to the landing gear and anything in between – need to be held together securely. Considering the immense load and stress to which an aerospace fastener that clamps two components together is subjected, it comes as no surprise that the materials, construction and insertion are quite different from their counterparts utilized in the construction or marine craft industries. Let’s use an example in order to better understand this concept.

 
A380 fasteners versus the ones used in the Golden Gate Bridge
The standard fasteners employed in high stress and load environments, such as the Golden Gate Bridge, is grade 8 strength. You can imagine that this particular structure has to bear the load of numerous heavy components as well as the vehicles that pass on a daily basis. Any failure would result in devastating – even life threatening – situations, as the entire bridge could collapse.
Now, a fastener for the standard air or spacecraft is typically at least 20% stronger, in addition to the substantially lighter weight. And that’s not all; the degree of complexity for the processes of inserting and tightening of fasteners for the wing assembly of an A380 plane model is considerably more complex. From the drilling coldwork slots to titanium inserts and/or lock-bolts, the job of the Electroimpact E4380 line is not an easy one.
Basically, every possible detail is rigorously controlled, not only to ensure that the weight is kept to a minimum, but also that the whole assembly holds without issues and the craft can achieve liftoff.
The main type of material utilized in the aerospace industry
Considering the aforementioned two features mandatory, namely high strength and light weight, titanium and titanium based alloys constitute the safest bet. However, while titanium was the main material utilized for over three decades, it performs poorly at extreme temperatures exceeding 1,000 degrees Fahrenheit. In this case, titanium is replaced with nickel alloys and multiphase substances.
Additional considerations
A fastener employed for the delicate instruments of a spacecraft is required to function optimally without the use of lubricant, which tends to vaporize in zero G conditions. Furthermore, for the fastening solutions exposed to liquid oxygen, the materials should not cause chemical reaction, as oxygen has to be maintained in an inert state.
Current advancements brought by the introduction of carbon composite materials in the aerospace industry promise to spark a revolution in terms of construction and properties pertaining to the fasteners utilized.

About the Author

Larry Melone
By Larry Melone
President

Started my career in the fastener world in 1969 at, Parker Kalon Corp. a NJ based screw manufacturer located in Clifton, NJ working in inventory control, scheduling secondary production and concluding there in purchasing. In 1971 I accepted a sales position at Star Stainless Screw Co., Totowa, NJ working in inside sales and later as an outside salesman, having a successful career at Star I had the desire with a friend to start our own fastener distribution company in 1980 named: Divspec, Kenilworth, NJ. This was a successful adventure but ended in 1985 with me starting Melfast in August 1985 and have stayed competitive and successful to date. Melfast serves the OEM market with approximately 400 accounts nationally.

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