Fasteners Used in Aerospace: Types, Materials & Characteristics of Aircraft Fasteners | CNCLATHING

2020.8.8

Even though an airplane is made of the best materials, if these parts are not firmly fixed together, its safety will be affected. The development of aircraft for commercial, shipping, and military, as well as ballistic missiles and rockets, puts significant performance pressure on aircraft fastener manufacturers. CNC machining for aerospace industry provides an effective solution for the aircraft components production, supplying numerous precision machined components each year. In this article, we’ll primarily discuss the types and materials of aerospace fasteners, as well as understand the characteristics and quality standards.

Fasteners Used in Aerospace Industry

Maybe it’s hard to show the effect of fasteners from the appearance, the fasteners are still a type of necessary accessories in the aerospace industry, aircraft fasteners can even account for about half of all parts, mainly used to assemble different parts and connect the assemblies into a complete device, as well as transfer loads from one part to another. Aerospace fasteners differ greatly to general commercial-grade fasteners, no matter in material grades, machining process, and performance characteristics. 

Aircraft Fasteners Characteristics and Quality Standards

Aviation fasteners need to be very durable to withstand extreme gravity stresses. They are important components that affect the overall safety and efficiency of the aircraft. All these fasteners must pass strict standard certification to manage their production and use. Due to the high precision and superior quality, aerospace fasteners can also be used in any equipment where requires precise components. Aircraft fasteners usually have high corrosion and oxidation resistance, high tensile, shear and fatigue strength, light weight, self-sealing and self-locking functions and the ability to withstand harsh environments, such as extremely high/low temperatures. 

 

AS9100 and AS9120 are U.S. and international quality management standards that are widely adopted for the aerospace industry, AS9100, BS9100 and EN9100 applies to organizations that design and manufacture products for the aerospace industry, including parts and assemblies, AS9120, BS9120and EN9120 applies to manufacturers and distributors supplying aviation parts for the aerospace industry.

Types of Aerospace Fasteners

A summary of the core types of fasteners used in the aviation sector, such as screws, bolts, nuts, washers, rivets, collars, gaskets and pins. 

Aerospace Screws: most commonly used threaded aircraft fastening devices, characterized by a helical ridge, known as a external thread. Compared to bolts, they are generally made of lower strength materials and can be installed with a loose fitting thread.

Aerospace Bolts: most bolts used in aircraft structures are typically general purpose, AN bolts, NAS internal wrenching or close tolerance bolts, or MS bolts, they can be fabricated from cadmium or zinc plated corrosion resistant steel, unplated corrosion-resistant steel, and anodized aluminum alloys.

Aerospace Nuts: a type of fastener with a threaded hole, always used in conjunction with a mating bolt or screw, can be made of cadmium plated carbon steel, stainless steel, or anodized 2024T aluminum alloy. Aircraft nuts can be divided into non self-locking and self-locking nuts.

Aerospace Rivets: a permanent mechanical fastener consists of a smooth cylindrical shaft with a head on one end, a rivet is used to hold two or more metal sheets, plates, or pieces of material together. The shank of the rivet is placed through matched holes in two pieces of material, and the tip is then upset to form a second head to clamp the two pieces securely together. 

Aerospace Washers: including plain, lock, or special type washers, generally constructed from stronger and more lightweight materials.

Materials of Aerospace Fasteners - Which Material to Choose for Aircraft

The fastener characteristics mainly depend on the material selected for the particular fastener construction, the common options including aluminum, steel, titanium and superalloys.

1. Titanium

Titanium is a perfect material for aerospace fasteners due to its outstanding properties, its strength is comparable to steel and alloy steel, but it is lighter, so it can be used to replace aluminum in some cases. Junying can deliver precision custom fastener products and other hardware made of a range of titanium materials with our CNC titanium machining services. Here is a comparison between common titanium and titanium alloys in aviation.

2. Aluminum 

A lightweight and affordable metal material widely used for manufacturing different aerospace parts, more often used for atmospheric planes, but has certain limitations and may needs additional surface treatment to get enhanced properties. The most common aerospace aluminum alloy is Al 7075, which has high strength and good fatigue strength. 

 

3. Steel

Steel can be up to three times stronger than aluminum, however, it is also heavier, which is the issue should be considered in CNC aerospace parts machining. The stainless steel and alloy steel are the main aerospace fastener materials. It’s challenging to select proper steel types and machining techniques. Steel is ideal for use on the aircraft surface and in the landing gear, some stainless steel types like PH and CRES stainless steels can be used for some fastener applications, like screws and bolts. 

 

4. Superalloys

Superalloys (high-performance alloys) is a kind of special material used in aircraft and aerospace, usually because of their stronger capabilities than other materials, including high versatility, the ability to maintain their structural and surface integrity in extreme environments, and their resistance to creep factors. Representatives among them are A286 (iron-nickel-chromium alloy), H-11 (5% chromium tool steel alloy), Hastelloy®, Inconel 718®, etc.