Screws are a type of threaded fastener used to join objects and hold them together. A screw consists of a head and threaded section which, depending on the design, may or may not flush out with the surface during fastening. There are many different types of screw heads including flat head, round head, raised head, truss head, bugle head, and more, each designed and used for a specific purpose. This blog will cover the many types of screw heads and their unique characteristics.

In their most basic form, screws are divided into two groups: countersunk screw heads and non-countersunk screw heads. In a countersunk screw head, there is an angular shape beneath the beneath the head, while in non-countersunk screw heads, there is a flat shape. To create the countersunk head, a countersink bit is drilled into the screw to provide the correct head angle. In non-countersunk screw heads, there is no pre-drilled hole necessary. In each group, there are many further classifications. Countersunk screw heads include flat heads, oval heads, and bugle heads, while examples of non-countersunk screw heads are pan heads, button heads, round heads, binding heads, flange heads, and socket heads.

Countersunk Screw Heads

The first type of countersunk screw head, the flat head, sits entirely in the same plane of the mating surface. These screw heads feature a flat top surface and a cone under the bearing surface with a standard of 82 degrees. These are ideal for use in areas where protrusion is unacceptable, such as in a bookshelf. Other applications of flat head screws include steel applications and door hinges. Oval heads are the same as flat heads but feature a dome-shaped head rather than a flat top, making them slightly more aesthetically pleasing without affecting performance. Finally, bugle heads have a flat top surface and a concave curve shape below the bearing to reduce surface damage. These heads are capable of distributing bearing stress over a wider area and are most commonly used in drywall.

Non-countersunk Screw Heads

Pan heads are the first type of non-countersunk screw heads. These feature a flat or slightly round head with chamfered edges and a flat load-bearing surface on the underside. Pan heads have moderate head height and diameter and provide high tightening torques. Button heads are domed, large diameter heads with high resistance to slipping and stripping. These are ideal for lighter fastening operations and will not be suitable for high strength applications. Round screw heads have a high profile and deep drive cut, but a smaller diameter. These were once the most popular types of screw heads but many now consider them outdated.

Binding heads are similar to pan heads, but feature a much thicker bearing surface and deeper slot, both of which increase the screw’s bearing capacity. A flange head can be considered a combination of a screw and washer. The head can be circular or hexagonal with a washer underneath the load bearing surface. This distributes pressure to help keep the screw in position and increase its bearing capacity. Finally, socket heads are the strongest type of screw head. Known for their quality and reliability, they are made from high grade carbon and stainless steel. Screw heads of this type feature a cylindrical head and long vertical sides. Their head height and shank diameters are equal, allowing them to be used in very high-strength endurance applications.

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Rivet nuts are a type of internally threaded fastener that is often used for materials that are brittle or thin, allowing for fastening solutions for components that are intolerable of hole tapping. The rivet nut features a one-piece design, allowing for it to be anchored from one side of the component. Rivet nuts were originally developed in 1936 for attaching rubber deicing boots to the leading edge of an aircraft wing, and they have since expanded their use to many more applications. In this blog, we will discuss the various types of rivet nuts and rivet materials that may be chosen from, enabling you to find which is best suited for your needs.

Also known as blind rivet nuts, such fasteners may either feature an open end or a closed end. With a closed end nut, the back end of the fastener is completely sealed out, preventing debris and contaminants from entering. To further protection, sealants may also be implemented to deter moisture and lubricants. When choosing which types of rivet nuts are best suited for your application, it is important to consider the torque value, grip range, rivet material, body style, parent material, environment, strength of the rivet, and size of the rivet.

Aluminum rivet nuts are a type that provides the means for facilitating simple connections and provides clean internal threads once installed. They are fairly easy to establish within components and often do not need finishing as well. In general, aluminum rivet materials have benefits such as resistance to corrosion, decreased weight, and high electrical and thermal conductivity.

Where there is a need for a fastener that provides high strength capability and resistance to corrosion, rivet materials such as stainless steel is very beneficial. Stainless steel is very durable, and its resistance extends to corrosion, fire, and heat. It also provides optimal strength to weight ratios, allowing for powerful fastening solutions without greatly increasing overall weight.

Brass rivet nuts are often reserved for implementation in applications where there is a need for a very versatile metal. For sheet metal, brass rivet nuts may be installed very quickly and provide an effective fastening solution, and they are favorable for a wide range of applications. In regards to their capabilities, brass rivet nuts feature good malleability and resistance to corrosion, as well as exceptional tolerance to temperature.

To install rivet nuts, a compression process is used to attach the fastener to the component. This is typically carried out with the use of a special rivet nut tool which squeezes the nut with in-line forces. Depending on whether the rivet nut body is smooth, swage, hex, or ribbed, various torque values may be utilized to ensure a proper installation that will be strong and effective. As various rivet nut types and materials each provide their own benefits, it is important to consider all aspects of the application so that you may find the perfect fit.

When it comes time to begin sourcing the aircraft rivet nuts that you need for your operations, Aerospace Unlimited has you covered with everything you are searching for. Aerospace Unlimited is owned and operated by ASAP Semiconductor, and we can help you find the aviation, NSN, and electronic parts that you are searching for, new or obsolete. As a premier supplier of parts for the aerospace, civil aviation, and defense industries, we're always available and ready to help you find all the parts and equipment you need, 24/7x365. ASAP Semiconductor is an FAA AC 00-56B accredited and ISO 9001:2015 certified enterprise. For a quick and competitive quote, email us at or call us at +1-412-212-0606.

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