Several varieties of screws, bolts and nuts are used for different types of fastening applications. Each little hardware component has a unique role to play, and shoulder screws are no exception to this. These components are also commonly referred to as shoulder bolts. Such screws are sometimes used as pivot points, and in some applications they are also used as a stopping or alignment mechanism.
They are designed and installed in a manner that permits the rotation of a mating part, such as a pulley, to move without restraint. Where a part needs to move, you will likely find a shoulder screw being put to use. These screws are very widely used in various types of automotive and mechanical applications too.
In the context of electronic and computer equipment, these screws are used for securing printer heads etc. There are large corporations such as Dell that have their proprietary line of shoulder bolts that are employed for fastening side rail kits to the chassis of server racks.
It is rather easy to identify shoulder screws. They usually have a cylinder-shaped head. However, you would also find screws with a square, hexagonal, or slotted head depending on varying requirements.
The drive of these screws is either slotted or cross-recessed. However, the defining attribute of these screws is their large unthreaded, cylindrical shoulder under the head. This shoulder runs down from the head towards a reduced-diameter threaded portion right till the tip of the screw. In some cases the unthreaded shaft might not be cylindrical, and could be square instead. The diameter of this plain shaft is slightly more than the threaded shaft of the shoulder bolt.
This unthreaded cylindrical shoulder is what sets this screw apart from other types of screws. As you would know, in a regular threaded screw the threaded portion stretches all the way from the tip to the head, with no plain portions in between.
You will notice that such screws are available in a variety of materials, each with its unique use in different applications. The most commonly available types of shoulder bolts are made using high grade alloy steel, free machining stainless steel, metric A1 or unified 303 raw material.
While selecting shoulder screws, you would need to carefully select their length and diameter to fit your application appropriately. If you are not confident about the right selection, you could always seek the professional opinion of a reputable supplier of metric fastening products. Such firms often specialize in other products such as sems screws. In applications where loose screws and washers cannot be easily installed, sems screws are the preferred choice.
Thus, using an appropriate shoulder screw allows for machine parts or materials to rotate or slide over.
